Practice Exam 2

1. Which of the following, if any, accurately describe what is meant by dual dipole tag? ❑ A. A tag that is configured to have two chips, giving it more processing power ❑ B. A type of tag’s antenna that is designed to reflect energy on multiple planes ❑ C. A tag that has overlapping layers of copper coils ❑ D. A tag that works on dual frequencies

Dual dipole tags were originally made with theorientation of the dipoles set 90 degrees apart. Today, however,multiple variations of this type of tag are available, with the dipolesarranged in many different patterns. They ensure tag reads regardlessof orientation. Most of them are designed so that they even read onedge or turned so they are perpendicular to the antenna. This is criticalfor retail applications where many boxes are being read, and orientationcannot be assured. Answer A is not correct because the questionrefers to the antenna on the substrate, not the chip. Answer C isincorrect because dual dipole does not refer to induction coils. AnswerD is also incorrect because tags cannot work on dual frequencies, andthey are not referred to as dual dipoles.

2. Which of the following, if any, are parts of the etching process? ❑ A. A mask ❑ B. Various chemical solutions ❑ C. Protection from oxidation ❑ D. All of the above

In the copper etching process, a mask is used to“burn” an image into the photopolymer layer. The substrate, or copperfilm, and photo resist are subjected to a chemical solution, whichremoves all of the copper except where the image was burned. A differentchemical solution is used to remove the “burned” photo resist.Then the finished copper antenna goes through additional processesto protect the copper surface from oxidation.

EtchingThe etching process works as follows:1. A mask is used to “burn” an image into the photopolymer layer.2. The substrate, metal film, and photo resist are subjected to a chemicalsolution that removes all of the metal except where the image was burned.3. A different chemical solution is used to remove the “burned” photo resist.4. The finished antenna goes through additional processes to protect themetal surface from oxidation.

Various methods and materials are used for antenna construction. The principle methods are

➤ Etching (using copper, aluminum, or silver) ➤ Foil stamping ➤ Screen printing

3. What is dwell time? ❑ A. The time a tag is in the interrogation zone ❑ B. The time it takes one tag to go from the pallet to the warehouse floor ❑ C. The rating system used to track build processes ❑ D. None of the above

Dwell time refers to the momentary time intervalduring which a detector is able to, or allowed to, sense incoming electromagneticradiation within its intended instantaneous field of viewor how long the tag stays in the interrogation zone. Ensuring that theantennas are oriented properly to maximize the interrogation field isvery important because, if the tags are in the interrogation zone fortoo short of a period, they may not collect enough energy to power upfully and report to the reader. Answer B is not correct because the dwell time is not the time of palletizing and inventory. Answer C isnot correct because dwell time has no bearing on a rating system.Answer D is incorrect by default.

4. When referring to RFID antennas, what does the acronym ERP mean? ❑ A. Enterprise Resource Planning ❑ B. Effective rate of protection ❑ C. Effective radiated power ❑ D. Unit of power input ❑ E. All of the above

Effective radiated power (ERP) is the power suppliedto an antenna multiplied by the antenna gain in a given directionor as the product of the power supplied to the antenna and its gainrelative to a half-wave dipole in a given direction. Answer A is not aterm used when referring to RFID antennas; however, EnterpriseResource Planning is a valid term in the business arena. Answer B is notcorrect because it is a fictitious term. ERP is not a unit of power inputbut a power radiated out of the antenna; therefore, answer D is incorrect.

5. When implementing an RFID system in Australia, what ITU region are you in? ❑ A. Region 1 ❑ B. Region 2 ❑ C. Region 3 ❑ D. Regions 1 and 2

The International Telecommunication Union (ITU) Regions are ➤ Region 1—Includes Europe, Africa, the Middle East west of the Persian

Gulf and including Iraq, and the former Soviet Union. ➤ Region 2—Includes the Americas. ➤ Region 3—Contains Asia (excluding the former Soviet Union), including

Iran, Australia, and Oceania.

6. What memory bank is used for User memory in EPC Class 1 Generation 2 tags? ❑ A. Bank 0 ❑ B. Bank 3 ❑ C. Bank A ❑ D. Bank B

➤ Bank 0—Reserved Memory—Reserved memory holds the tag’s passwords and can be read locked.➤A 32-bit Kill password allows a tag to be permanently silenced. Thedefault Kill password value is zero. The Kill command executes only ifthe password has been set; that is, it is something other than zero.➤A 32-bit Access password allows the tag to transition to the Securedstate (a tag in the Secured state can execute all Access commands,including writing to locked blocks).

➤ Bank 1—EPC Memory—EPC memory contains 32 bits for differentprotocol controls and a 96-bit EPC (Electronic Product Code) of theobject the tag is attached to.

➤ Bank 2—Tag Identification Memory (TID Memory) —TID memorycontains an 8-bit ISO allocation class identifier, a 12-bit tag maskdesignerID, and a 12-bit tag model number. Manufacturers can includeother information, if required—for example, a tag serial number.

➤ Bank 3—User Memory—User memory is an optional area of memory(usually 32-bits but can be larger) that contains user-specific data. Thememory organization is user defined.

7. Which of the following is/are characteristics of an active tag? ❑ A. An active tag is powered by a battery to send and receive

RFID information. ❑ B. An active tag can be applied to any surface and has the ability to transport

itself from one location to the next. ❑ C. An active tag can be interrogated within a few inches of the interrogator,

and it is powered by the interrogator. ❑ D. An active tag does not have its own transmitter in comparison to a

passive tag.

Active tags have an internal battery to powerthem and are usually able to be rewritten and/or modified. Active tagscan transmit their data over longer distances; the tag itself is largerthan a passive tag and has a limited operational life span. Answer B isincorrect because active tags cannot “magically” transport themselves;they are carried on a product. Answer C is incorrect because activetags are not generally powered by interrogator; they have their ownpower source. Active tags have their own transmitter; therefore,answer D is also incorrect.

8. What are some of the uses for a Low Frequency RFID tag? ❑ A. Pet tracking ❑ B. Smart shelves ❑ C. Paper plates ❑ D. Access control systems

Low Frequency RFID tags are commonlyused for animal identification. Pets, cattle, or endangeredspecies can be implanted with small chips so that they may bereturned to their owners if lost or stolen or for scientific purposes.Low Frequency systems are best for tracking and identification ofdense objects in small ranges because they provide good penetration.Therefore, answer C is incorrect because paper plates are not a barrierto RF and are not usually tracked with LF systems. Answer B is incorrectbecause LF systems are not usually used in “smart shelves.”

9. What does the term inductive coupling mean? ❑ A. A method of connecting different devices together ❑ B. A way of fusing data to the back-end application ❑ C. The process of fixating the fixtures of the antenna so they do not move ❑ D. A method of transmitting data between tags and readers

Inductive coupling is the method of transmittingdata between passive tags and readers in which the antenna from thereader picks up changes in the tag’s antenna. Answers A and B are notcorrect because the term refers to data transmission, not connection ofdevices or data subject to back-end systems. Answer C is not correctbecause the term does not refer to attachment of hardware.

10. What is the EPC network? ❑ A. It is a network like the Internet, also storing and retrieving information on EPC

products. ❑ B. It is a network protocol that allows only the environmental specialist access to

data on the Internet. ❑ C. It is a computer storage location that holds information on all electronic codes. ❑ D. None of the above.

The EPC network is architecture similar to theInternet; it is designed to link, store, and allow access to data relatedto EPCs. For example, it provides detailed item information such asdescription, ingredients, size, weight, and cost; manufacturing informationabout the specific lot, such as when and where it was producedand expiration dates; and distribution information about where it hasbeen, including addresses, dates, and times. The data can be asdetailed as including environmental factors such as temperatures duringmanufacturing or storage. Answer B is not correct because thequestion refers to RFID terms. Answer C is not correct because theEPC network contains only data related to the EPC global system.Therefore, answer D is incorrect as well.

The EPCglobal network is composed of three key elements:

➤ EPC Information Services (EPC-IS) ➤ EPC Discovery Services ➤ Object Name Service (ONS)

11. In a conveyor system, why is it important to test the tunnel interrogator radiated field?

❑ A. Metal areas are not an issue in testing. ❑ B. There is no special need to test on a standard conveyor system. ❑ C. Typical conveyor systems are made of metal, and the radiated signal

can be configured in a way that the interrogator reads tags from another belt system nearby, resulting in failed or error reads.

❑ D. You need to ensure that the tags are read as far as possible from the tunnel to increase efficiency.

Most conventional conveyor roller sections aremade of metal, and the metal structure acts as a boundary condition tothe radiated flux field. Thus, consideration must be given to preventthe absorption and distortion of the magnetic and radio field energy.Answer A is not correct because metal areas are of high concern in anRFID solution. Answer B is incorrect because testing is extremelyimportant to any system. If you increase the power input into theantennas in the RFID tunnel, the interrogation field may expandbeyond the tunnel, and that could cause false or undesirable reads;therefore, answer D is incorrect.

12. What does the term inlay refer to? ❑ A. An RFID microchip attached to an antenna and mounted on a substrate ❑ B. The process that fuses a chip to a container ❑ C. The method of regenerating a tag ❑ D. A chip mounted on a strap

An inlay is an RFID microchip attached to anantenna and mounted on a substrate. Inlays are essentially unfinishedRFID labels. They are usually sold to label converters who turn theminto smart labels. Answers B and C are not correct because an inlay isnot defined as the ability to connect a tag to a container, nor is it amethod of writing data to a tag. Inlay does not refer to a chip on astrap; therefore, answer D is also incorrect.

13. What is a circular polarized antenna? ❑ A. An antenna that can receive signals from both vertical and horizontal planes ❑ B. A round antenna ❑ C. A disc-shaped antenna ❑ D. None of the above

Antennas with circular polarization can receivesignals from both the vertical and horizontal planes; however, there isa slight loss of signal strength. Answers B and C are not correctbecause the question refers to the planes on which the antenna canread tags. Answer D is incorrect by default.

Polarization can be either circular or linear. Linear polarization is relative tothe surface of the earth. Linear polarization can also be either horizontal orvertical:

➤ Horizontally polarized signals propagate parallel to the earth. ➤ Vertically polarized signals propagate perpendicular to the earth.

Antennas with circular polarization can receive signals from both the verticaland horizontal planes by injecting the signal at two points on the antennaradiated slightly out of phase creating a rotating effect on the field.However, there is a slight loss of signal strength, due to the constructive anddeconstructive effect of the field being slightly out of phase.

14. Which of the following, if any, are characteristics of a tethered interrogator? ❑ A. Have limited mobility ❑ B. Do not need a self-contained power source ❑ C. Connect directly into the IT infrastructure ❑ D. All of the above ❑ E. None of the above

Tethered interrogators are tied directly into theIT infrastructure, and they do not need their own power because theyare typically connected to a power source through a power cable.They have limited mobility due to their wired connections to otherdevices and to their external power source.

15. Microwave (uW) tags operate at what frequency? ❑ A. 860–960 MHz ❑ B. 2.45 GHz ❑ C. 120–140 KHz ❑ D. 13.56 MHz

Microwave tags operate at 2.45 GHz. Answer A isincorrect because Ultra High Frequency (UHF) tags use the 860–960MHz band. Answer C is incorrect because Low Frequency (LF) tagsoperate in the 120–140 KHz band. Answer D is incorrect becauseHigh Frequency (HF) tags operate at 13.56 MHz.

The four primary frequency bands for RFID tags are ➤ Low Frequency or LF (120–140 KHz) ➤ High Frequency or HF (13.56 MHz) ➤ Ultra High Frequency or UHF (860–960 MHz) ➤ Super High Frequency/Microwave (2.45 GHz and above)

16. What is a hybrid interrogator? ❑ A. A reader that has been altered with firmware to function as an FM radio ❑ B. A reader that has multiple read modes, such as the ability to read bar codes as well

as RFID tags ❑ C. An interrogator that also can function under water ❑ D. All of the above

Depending on their type, interrogators can havevarious capabilities such as reading bar codes or other Automatic DataCollection (ADC) capabilities. These are called hybrid interrogators.Answer A is not correct because RFID does not function as an FMradio. Answer C is incorrect because interrogators that can functionunder water are not called hybrid. Consequently, answer D is incorrectas well.

17. What indicates the efficiency of energy in an RFID chip? ❑ A. Q factor ❑ B. E factor ❑ C. H field ❑ D. E field

The Q factor indicates the ratio of the energystored in it to the energy lost during one cycle of operation. Answer Bis incorrect because the E factor is not defined. Answer C is incorrectbecause H field is a name for a magnetic field that can be createdaround the tag. Answer D is incorrect because the E field is the electricalfield caused by electric current.

Calculation of a Q factor for an electrically resonant system is following:

Where fc is a resonant frequency (center frequency).Calculation of a Q factor in a tuned radio frequency receiver is following:

Where R is resonance, L is inductance, and C is capacitance.

18. How would you protect your interrogator against extreme temperatures? ❑ A. No special protection is needed. Interrogators usually have a built-in

component that detects overheating of the device and turns the device off. ❑ B. By enclosing the interrogator in a NEMA box with heating and/or a

cooling device. ❑ C. By installing a fan near the interrogator. ❑ D. Interrogators are built to work in extreme temperatures. It is only necessary

to protect interrogators from liquids.

As far as we know, interrogators do not yet have abuilt-in detector from overheating. Therefore, answer A is incorrect.Answer C is incorrect, because although a fan could help, in extremelywarm or cold temperatures, this would not be sufficient to preventdamage of the interrogator’s circuitry. Answer D is also incorrect. It isnecessary to protect interrogators from extreme temperatures as wellas liquids and other harsh environmental conditions.

19. What is a dwell time? ❑ A. The time that a tag is in the radiated signal to allow for operations such as write

and read to occur ❑ B. The time when the conveyor belt opens the trip light ❑ C. The trigger device time used to start an interrogation process ❑ D. Time between the tag application and tag verification ❑ E. All of the above

An RFID tag, once energized, requires a certainamount of time to power up, and then it can respond to the interrogator.It is important that the RF energy that is energizing the tagremain at a level sufficient to sustain the tag’s functionality until it hassuccessfully retrieved data from or stored data to its memory. Becausethe tag can be powered only when it is in the beam of the RFIDantenna(s), the tag must remain in the beam long enough for therequired operations to occur. This is known as “dwell time.” If thedwell time is too short, the tag may power down prematurely, and theread or write operation will not be completed. One way to maximizethe tag’s dwell time or time in beam is to position the antennas so thatthe sweet spot is as large as is practical. Answers B and C are not correctbecause the question refers to the amount of time it takes for thetag to power up and send data back to the interrogator while theinterrogator is emitting a signal, not the hardware triggering devices.Answer D is incorrect because dwell time refers to the time in theinterrogation signal, not time between application and verification.

20. What is the use of an RTLS? ❑ A. Rotational Training and Limited Support is used to evaluate systems with other

electronic devices. ❑ B. Reality Television Life Stories are based on reporting of personal experiences on

reality television programs. ❑ C. RTLS is used to track and locate tagged RFID items. ❑ D. RTLS is used to measure ambient noise. ❑ E. None of the above.

Real-Time Location System (RTLS) uses RFIDtechnology to transmit the physical location of RFID-tagged objects.An RTLS requires some type of RFID tag to be attached to eachobject that needs to be tracked and RF transmitters/receivers locatedthroughout the facility to determine the location that sent that locationinformation back to a computerized tracking system. Answer A isnot correct because the term RTLS means Real-Time Location System,not Rotational Training and Limited Support. Answer B is not correctbecause RFID at this time has nothing to do with television or programming.RTLS is not used to measure ambient noise; for thispurpose, the RF spectrum analyzer is used. Therefore, answer D isincorrect.

21. Consistent failed tag reads indicate that the tag supplier is at fault. ❑ A. This statement is true. ❑ B. This statement is false because consistent failed tag reads can indicate

interrogator problems. ❑ C. This statement is false because consistent failed tag reads indicate a

problem with the tag antenna. ❑ D. This statement is true only for UHF tags.

Consistent failed tag reads should immediatelyraise a “red flag” that the interrogator is not functioning properly. Areplacement interrogator (possibly a handheld unit) should be used toverify a second time if the tags are functioning. Answer C is not correctbecause, if the tag’s antenna was damaged, this would cause only afew tags to be invalid but not consistent failure with all tags. AnswersA and D are incorrect.

22. How can you achieve full 14-digit Global Trade Item Number (GTIN) from a data carrier of a shorter digit length?

❑ A. Add zeros to the back of the number to achieve 14 digits. ❑ B. Add zeros in front of the number to achieve 14 digits. ❑ C. Add a code assigned by EPCglobal to the front of the number. ❑ D. Add a code assigned by EPCglobal to the back of the number.

To achieve full 14-digit GTIN from a data carrierthat uses less digits, for example EAN.UCC-13, EAN.UCC-8 orUCC-12 (UPC), add zeros to the front of the number. Therefore,answer A is incorrect. EPCglobal does not provide a code to add tothe number to convert it to 14-digit GTIN.

23. For which of the following are RFID systems used? ❑ A. Tracking assets ❑ B. Toll collection ❑ C. Security purposes in entertainment parks ❑ D. All of the above

RFID systems can be used for many applications,including asset tracking, clothing tags, missiles, pet tags, and food.RFID can be used to track transportation variances such as temperature,humidity, and expiration dates. RFID tags can store simple informationsuch as a pet owner’s name and address, whether the pet hashad all of its shots, and if those shots are current, to complex data suchas instructions on how to assemble a computer. Some manufacturersuse RFID systems to move objects through assembly lines. At each successive stage of production, the RFID tag tells the back-end systemwhere it is in the build process and what the next step of assembly is.This information can then be presented to the intended purchaser ofthe item through web page applications or telephone response systems.RFID can also be used for security purposes to allocate personsin a facility or area, as well as for toll collection.

24. What is an RS-232 serial data port? ❑ A. An Electronics Industries Association standard asynchronous serial line, which is

used commonly for modems, computer terminals, and serial printers. RS-232 uses a 25-pin or 9-pin connector.

❑ B. A serial input/output standard that allows for compatibility between data communication equipment made by various manufacturers.

❑ C. A method of sending data over wires. It is often used to communicate between interrogators and printers or computers, as well as the backend systems.

❑ D. This is the de facto standard for communication through PC serial ports. It can refer to cables and ports that support the RS-232 standard.

❑ E. All of the above.

RS-232 is a standard that defines the communicationrules for serial ports and how they communicate with readers andback-end systems. Therefore, answers A, B, C, and D are incorrect.

25. What is a mono-static antenna? ❑ A. An antenna that has two distinct radiated signals in one case. ❑ B. An antenna that can be coupled with only one interrogator. ❑ C. A single antenna that works as a transmitter as well as a receiver. ❑ D. Mono-static antenna is another name for single dipole antenna. ❑ E. All of the above.

Depending on the design, the antennas can beeither mono-static or bi-static. Mono-static antennas are based on aprinciple wherein a single antenna works as a transmitter as well as areceiver, and these functions are switched in fractions of seconds.Answer A is not correct because the question refers to the hardware,not the signals that can be generated. Answer B is not correct becausethe question refers to how the system transmits, not how it connectsto the system. The term mono-static is not interchangeable with singledipole; therefore, answers D and E are incorrect.

Bi-static antennas include two antennas, where one antenna is dedicatedto transmitting, and the other antenna is dedicated to receiving. Bothdedicated antennas can be but do not have to be in the same casing. Inbi-static antenna, a circulator is not required, which improves the performanceand sensitivity of the antenna.

26. Which of the following is a part of an RFID system? ❑ A. An antenna ❑ B. A transceiver ❑ C. A processing device ❑ D. A tag ❑ E. All of the above

An RFID system consists of an antenna and atransceiver, which read the radio frequency signals and transfer theinformation to a processing device; and a transponder, or tag, which isan integrated circuit containing the RF circuitry and information to betransmitted.

27. Which of the following are uses of microwave RFID tags? ❑ A. Collecting electronic tolls ❑ B. Tracking microwavable food ❑ C. Opening and unlocking the microwave door ❑ D. None of the above

Microwave RFID tags are typically used in electronictoll collection. However, they are becoming access controldevices used for long-range access control for vehicles as a part ofOnStar systems in many General Motors vehicles sold today. AnswersB and C are not correct because the question does not refer to amicrowave oven. Consequently, answer D is incorrect as well.

28. What is a bi-static antenna? ❑ A. An antenna that has two distinct radiated signals. ❑ B. An antenna device that allows one antenna to connect to two interrogators. ❑ C. An antenna that combines two antennas (sometimes within one case):

one for transmitting and the other for receiving. ❑ D. Bi-static antenna is another name for dual dipole antenna.

Depending on the design, the antennas can bemono-static or bi-static. A bi-static antenna combines two antennasthat can sometimes be within one case. One antenna is dedicated totransmitting, and the other antenna is dedicated to receiving. AnswerA is not correct because the question refers to the hardware, not thesignals that can be generated. Answer B is not correct because thequestion refers to how the system transmits, not how it connects tothe system. Although the bi-static antenna can be dual dipole, theterms are not generally interchangeable. Therefore, answer D is incorrect.

29. When referring to RFID technology, what does the acronym EIRP mean? ❑ A. Enterprise international resource planning ❑ B. Effective isotropic radiated power ❑ C. Effective independent rotational potential ❑ D. None of the above

Effective isotropic radiated power (EIRP) is thearithmetic product of the power supplied to an antenna and its gainrelative to an isotropic source. EIRP = Power input * antenna gain indBi. Answers A and C are fictitious terms. Answer D is incorrect bydefault.

30. In a dense interrogator environment, the presence of many interrogatorstransmitting simultaneously at the same frequency can

❑ A. add additional power to a tag so that it can backscatter farther thanwith one interrogator transmitting to it.

❑ B. potentially cancel each other out by emanating large amounts of backgroundnoise that will overpower all the interrogators if not configured properly.

❑ C. be solved by designing the interrogator placement and their configurations. ❑ D. Overload the power circuits.

Signals transmitted to a tag from oneinterrogator can easily be “stepped on” by another interrogator. Inaddition, the reply signal from a tag can easily be stepped on as well.Correct placement of the interrogators can help avoid this type ofinterference from occurring. Answer A is incorrect because it is physicallyimpossible to accumulate RF signals at a tag prior to backscattering.Answer D is incorrect because the circuit overload in the denseinterrogator environment is not the best answer here.

31. Define slap and ship. ❑ A. A minimal compliance step ❑ B. An advanced stage of RFID implementation ❑ C. A method of using RFID as an inventory control system ❑ D. None of the above

Many companies are simply trying to complywith mandates, and they begin doing so by using RFID devices in distributioncenters immediately before shipping the products to themandating customer. RFID printers/encoders can be quickly and relativelyeasily implemented, and as long as there is a small volume ofgoods being shipped, they are quite effective. This initial step of minimalcompliance has been called slap and ship. Answers B and C are notcorrect because the question refers to the compliance of a mandateand a method of application using RFID technology. Answer D istherefore incorrect as well.

32. What is ambient RF noise? ❑ A. Radio signals that enhance the reception of the target RF signal ❑ B. RF signals emitted by several devices into the environment ❑ C. Another term for white noise that allows the operator to concentrate on the task ❑ D. An interchangeable term for interrogation signal

Ambient noise is RF signals generated by somethingother than the transmitter. It usually sounds like a hiss—static orharsh. Radio frequency interference (RFI) may be AM or FM, but theeffect is that it either alters the audio signal or adds background noiseto the audio signal. Answer A is not correct because of the term noise,which is not desirable in the RF signal as it can cause read failures.Answer C is not correct because the RF signal has nothing to do withthe operator and the concentration level of the operator. Although theinterrogation signal can produce ambient noise, these terms are notinterchangeable. Therefore, answer D is incorrect.

33. My interrogator is reading the tag data, but it is not being recognizedby my application as valid data for the products it is supposed to beassociated with. The tag manufacturer sent me the wrong lot of tags.

❑ A. This statement is true. ❑ B. This statement is false; the problem is in the interrogator. ❑ C. This statement is false; the problem is in the configuration of the application. ❑ D. This statement is false; the situation indicates that the tags are all killed.

In a situation in which tags that have been programmedand attached to products are not being recognized in a databaseapplication, the application that performs the filtering should bechecked to make sure it is configured for the expected tag data format.In many situations, the application has not been properly configuredto match the tag data format. Answers A, B, and D are incorrect.Answer B is incorrect because the interrogator was proven to be reading tags; the problem appeared in the application software.Answer D is incorrect because the interrogator was successfully readingtags; if the tags were killed, the interrogator would not receive anyresponse from the tags.

34. A light stack is generally used to verify that a reader is turned on. ❑ A. This statement is true. ❑ B. This statement is false because a light stack is used to indicate that the

reader is turned off. ❑ C. This statement is false because the light stack is a feedback device to

indicate whether the tag functions. ❑ D. This statement is false because light stacks are not used in RFID systems.

The light stack is primarily used as an indicatorthat the tag is functional and replying to interrogation commands.Therefore, answers A, B, and D are incorrect.

35. The EPC number can be found in EPC Class 1, Generation 2 memorybank number

❑ A. 0. ❑ B. 1. ❑ C. 5. ❑ D. None.

There are four memory banks in EPC Class 1,Generation 2. These banks are numbered 0, 1, 2, and 3, and the EPCnumber is allocated in the bank 1 called EPC memory. Therefore,answers A, C, and D are incorrect.

36. What is the capability of a read-write tag? ❑ A. The ability to erase the tag data ❑ B. The ability to read data from the tag as well as write data to the tag ❑ C. The ability to kill the tag (EPC tags) ❑ D. All of the above

The read-write characteristics of the tag give theability to read and write data to the tag from any location, making thetag reusable, as well as the ability to remove most data and the abilityto kill the tag when talking about EPC tags.

37. Which of the following are uses for UHF RFID tags? ❑ A. Pallet tracking ❑ B. Container tracking ❑ C. Tracking laptops ❑ D. Tracking airplane parts

UHF RFID tags are commonly usedcommercially in pallet and container tracking. These tags operatebetween 860 MHz and 960 MHz. UHF tags are able to send andreceive data faster and at greater distances than LF and HF tags. Inaddition, these tags are limited due to the fact that the radio waves atthese high frequencies do not perform well around water and metal,so they are not usually used for tracking laptops and airplane parts dueto their high metal content. Therefore, answers C and D are incorrect.

38. The manufacturing process by which chips are taken directly from awafer and attached to an antenna is known as

❑ A. Flip chipping ❑ B. High rolling ❑ C. Fluidic Self-Assembly ❑ D. Strap attachment

The chip is taken directly from a wafer by robotichand, flipped and, with adhesive and pressure, attached directly to theantenna. Answer B is incorrect because high rolling is what everyonewishes to do when in Las Vegas. Answer C is incorrect because FluidicSelf-Assembly is the process of placing chips on the strap or antenna,where chips cut out of the wafer are floating in a liquid, and due totheir shape, they fall into precut holes. When the chips are takendirectly from a wafer and attached to an antenna, they do not use astrap attachment; therefore, answer D is incorrect.

39. What is a smart label? ❑ A. A smart label is an applied label that adheres to a container without

the need for adhesion. ❑ B. A smart label is a printed label that has all the shipping information

printed to the substrate. ❑ C. A smart label is a type of tag that is a flat, thin, flexible form using

usually paper or very thin plastic. It is used in RFID printers andapplicators.

❑ D. None of the above

Smart labels are labels that contain an RFID tag.Smart labels have limited memory capacity—currently between32–256 bytes—that can be read or written to multiple times by meansof an interrogator that connects to a PC. Answer A is incorrectbecause a smart label is not a label without a need for adhesion; it is aspecial type of label with an RFID tag embedded. Answer B is also incorrect; this type of label is a pure shipping label, and if it does notcontain an RFID tag, this label cannot be called “smart.”

40. Which of the following are reasons why you would use a bi-staticantenna instead of mono-static antenna?

❑ A. Bi-static antennas do not use a circulator for switching betweenreceiving and transmitting functions, therefore, they are more efficient.

❑ B. Bi-static antennas are cheaper. ❑ C. Bi-static antennas use a circulator for switching between receiving and

transmitting functions, therefore, they are more efficient. ❑ D. Bi-static antennas are used only with active RFID systems. For passive

systems, you would only use mono-static antennas.

Since bi-static antennas do not use a circulatorfor switching between receiving and transmitting, they are more efficient.Answer B is incorrect. The price of the antenna depends on thedesign and manufacturer of the antenna and not whether it is bi-staticor mono-static. Answer C is incorrect because bi-static antennas donot use a circulator for switching between receiving and transmittingfunctions. Answer D is incorrect because active and passive RFID systemsuse both kinds of antennas.

41. What is shadowing? ❑ A. One tag is in front of another, causing the second tag to have a depreciated

signal or no signal at all. ❑ B. All the tags that are not in the light of the tunnel cannot be read until

they are illuminated. ❑ C. This term defines what happens when the tag completely blocks the

interrogation signal coming from the interrogator. ❑ D. Shadowing occurs when the tag is in the “hole” of antenna coverage.

Shadowing is a situation in which tags are rightbehind each other and the RF signal produced by the reader’s antennais used by the first tag to generate a response, while the second taggets minimal or no signal and has no chance to respond to interrogation.The second tag is “in the shadow” of the first tag. Answer B isnot correct because “the light” in the tunnel does not perform a taskof reading a tag. Answer C is not correct because the tags are notcapable of blocking completely the interrogation signal. When the tagis in the “hole” of antenna coverage, this occurrence is not called shadowing;therefore, answer D is incorrect.

42. What is the definition of a read range? ❑ A. The device that reads RFID tags ❑ B. The area of the signal, such as the zone ❑ C. The maximum distance that a reader can send or receive data to or

from an RFID tag ❑ D. None of the above

The read range is the maximum distance atwhich a reader can send data to or receive data from an RFID tag.Answers A and B are not correct because the question refers to rangeor distance, not devices such as an interrogator or a zone. Answer D isincorrect by default.

43. What is diffraction? ❑ A. A deflected signal that expands as it travels ❑ B. A trigger that is tripped by a light diode ❑ C. Signaling that allows for wave-like action to occur ❑ D. None of the above ❑ E. All of the above

The process whereby RF signals or sound wavesare in certain circumstances deflected from their normal straight-linepath by physical objects is called diffraction. Diffraction is the apparentbending and spreading of waves when they meet an obstruction. It canoccur with any type of wave including electromagnetic waves such asradio waves. Answer B is not correct because the question refers to thesignal behavior, not actual hardware interaction. Answer C is not correctbecause signals already have wave-like behavior, and the questionrefers to a signal that encounters an obstacle. Answers D and E aretherefore incorrect as well.

44. What does antenna gain mean? ❑ A. The ability to increase the height of the antenna ❑ B. The relative increase in radiation at the maximum point ❑ C. The ratio of the radiated signal divided by the distance to the tag ❑ D. The amount of power an antenna can receive ❑ E. All of the above

Gain is the relative increase in radiated signal,usually expressed in dB, transmitted by a given antenna as comparedto an isotropic or dipole antenna. Antenna gain can be achieved onlyby making an antenna directional, which means better performance inone direction than in others, thus improving attenuation. Answer A is not correct because gain refers to the signal strength, not the height ofthe antenna. Answer C is a fictitious reply, which has no meaning inRFID technology. Answer D is incorrect because antenna gain is notthe amount of power an antenna can receive. The power input is specifiedin the manufacturer’s manual and is limited by the standards and regulations.

45. Which of the following are characteristics of EPC Gen 2 systemscompared to EPC Gen 1 systems?

❑ A. A more advanced Dense Reader Mode ❑ B. Faster read rates ❑ C. Larger ASIC chips in tags ❑ D. Using 16-bit lock password

Part of the EPC Gen 2 specifications arebetter functionality in a dense reader environment and faster readrates. The new ASIC chips used in EPC Gen 2 tags are actually smallerthen Gen 1 chips, therefore, answer C is incorrect. Answer D isincorrect because EPC Gen 2 tags use 32-bit kill and 32-bit lockpassword.

46. EPC Class 1, Gen 2 describes the Air Interface Protocol as well asthe data standard for communications between a Class 1, Gen 2interrogator and the tag.

❑ A. This statement is true. ❑ B. This statement is false; the protocol defines only the communication

between interrogator and back-end systems. ❑ C. This statement is false; the protocol covers just the Air Interface. ❑ D. This statement is false; the protocol defines only EPC Class 0.

The protocol covers the Air Interface Protocoland data standard; therefore, answer C is incorrect. The protocol,however, has nothing to do with the physical interface between a readerand other devices such as database servers, and so on. Therefore,answer B is incorrect. The Air Interface Protocol is defined for everyofficial EPC class—class 0 as well as class 1. Therefore, answer D isincorrect.

47. What is RS-422? ❑ A. The serial standard for connecting a viewable television monitor to a

handheld device ❑ B. A Radio Shack connector 422 copper three-wire phone line ❑ C. A differential pair of wires, as one signal is transmitted across two separate

wires in opposite states—one inverted and one noninverted used mainly to connect a printer to a workstation

❑ D. None of the above

RS-422 is a port to allow systems to print tags, ifthe tag printer uses this type of port. Answer A is not correct; youwould not connect a viewable monitor to a handheld device becausemost have built-in LCD displays. Answer B is incorrect because RS-422 is a port used to connect a printer. Answer D is incorrect bydefault.

48. Which of the following are applications for which High FrequencyRFID tags are not usually used?

❑ A. Pallet tracking ❑ B. Library books ❑ C. Electronic Article Surveillance ❑ D. Smart shelves ❑ E. All of the above

High Frequency RFID tags are not usually usedfor pallet tracking but are used in library books and bookstore tracking,building access control, airline baggage tracking, and apparel itemtracking. They are used in smart shelves due to their small size andsmall range. High Frequency tags are widely used in identificationbadges, replacing the magnetic stripe cards that are similar to creditcard systems. These High Frequency RFID badges need to be heldwithin a certain distance of the reader to authenticate the holder.Therefore, answers B, C, D, and E are incorrect.

49. What is a tag’s write range? ❑ A. The device that writes RFID tags with the correct data ❑ B. The distance between a reader and an RFID tag over which data-writing

operations can be reliably performed ❑ C. The space of the substrate that allows for proper printing ❑ D. None of the above

Write range is the maximum distance between areader and an RFID tag over which data-writing operations can bereliably performed. Answers A and C are not correct because thequestion refers to distance, not the actual hardware of the system orthe components of a tag. Answer D is incorrect by default.

50. Vehicle mounted interrogators ❑ A. are typically mounted on forklifts or clamp trucks. ❑ B. use the slotted Aloha protocol to communicate with tags. ❑ C. can withstand submersion in water. ❑ D. all of the above.

Answer B is incorrect because the Gen 2 protocolis not the same as the slotted Aloha protocol. Answer C is incorrectfor this question, but it is possible that a manufacturer can make sucha claim. Answer D is incorrect by default.

51. A new version of interrogator firmware should always be downloadedinto a reader when

❑ A. it is commercially available to keep the interrogator in tip-top shape. ❑ B. it seems that the interrogator is not working properly. ❑ C. it is released to fix problems discovered in a previous version. ❑ D. it appears on the manufacturer’s website.

Interrogators need not necessarily havetheir firmware upgraded if the existing configuration proves to providethe necessary functionality. It is useful to upgrade the firmware if it isreleased to fix problems in the previous version, or if the interrogatoris not working properly and the problem may be caused by “ bugs” inthe firmware. Answer A is not correct because the firmware shouldnot be upgraded just because a new version is available, if the systemfunctions properly. When new firmware appears on the manufacturer’swebsite, this is not a sufficient reason to upgrade the firmware rightaway. Therefore, answer D is incorrect.

52. Electrostatic Discharge (ESD) is often used to power up tags andprovide the needed energy to transmit back to an interrogator.

❑ A. This statement is true. ❑ B. This statement is true only with passive RFID systems. ❑ C. This statement is false because ESD is harmful to tags.

Electrostatic Discharge (ESD) is very harmful totags and can often destroy them. Therefore, answers A, B, and D areincorrect.

53. What is multiplexing? ❑ A. Doing many tasks at one time ❑ B. Applying various substrates together ❑ C. Switching between multiple antennas connected to one interrogator ❑ D. Combining two or more information channels onto a common transmission

medium using hardware called a multiplexer that is not used in RFID

In this method, a single interrogator is connectedthrough a switching box to multiple antennas. The interrogator outputis directed to each antenna in turn, again ensuring that only oneantenna is transmitting at a time. Answer A is not correct becausemultitasking is defined as doing more than one task at a time. AnswerB is not correct because the question does not refer to tags but ratherto antennas and interrogators. Multiplexing is a method of combiningtwo or more information channels onto a common transmissionmedium using hardware called a multiplexer, but it is used in RFID;therefore, answer D is incorrect.

54. What is the definition of an interrogation signal? ❑ A. A radiated signal sent to a zone or area intended to activate a reply from a tag ❑ B. The area or zone that is built for tags to pass through ❑ C. Often called the interrogation zone or Faraday Cage ❑ D. All of the above

An interrogation signal is meant to be received bya tag, and while passing over the tag, it activates the tag, causing it towaken and reply to the interrogator with the data stored. Answers Band C are not correct because the question refers to a signal, not azone or a device. Answer D is incorrect by default.

55. What acts as a protective shield for an interrogator or an antenna? ❑ A. A padded bollard ❑ B. Foam rubber tape ❑ C. Corrugated cardboard ❑ D. All of the above

Answer B is incorrect because B can comprise abollard. Answer C is not correct because cardboard (corrugated orotherwise) does not afford enough cushioning. Answer D is incorrectby default.

56. What is a linear polarized antenna? ❑ A. An antenna that radiates a signal in a conical shape ❑ B. An antenna that is designed to work in a cold environment ❑ C. An antenna that is set to a plane, either horizontal or vertical, and the

tags must be in the same plane ❑ D. An antenna that radiates signals whose strength linearly decreases with

distance from the antenna

When using a linear polarized antenna, the tagreader and antenna reader must be in alignment to achieve the longestreading distance. If that tag antenna is aligned vertically and the readeris sending out signals horizontally, only a small portion of the energy emitted by the reader will hit the tag antenna. Answer A is notcorrect because the question refers to the planes (horizontal or vertical),not the actual shape of the signal. Answer B is not correct becausethe polarization of the antenna defines the plane that it can read from,not the temperature of the environment. The radiated signal does notdecrease in a linear manner with distance because the loss is not linear.Therefore, answer D is incorrect.

57. What is the meaning of read-only? ❑ A. The data on the tag can be only read and not written by the interrogator. ❑ B. Read-only means that the tag is readable only when in the Faraday Cage. ❑ C. Read-only is defined as the ability to read the tag many times but still

allow rewriting the tag at any time. ❑ D. Data on read-only tags can be read and written only by the tag manufacturer.

The tag is capable only of being read many times,but not modified or rewritten. Answer B is not correct because aworking interrogator can read any functional tag without the need fora tunnel that works as Faraday Cage. Answer C is not correct; readonlymeans that the tag cannot be written to again because the data isprewritten by the manufacturer. Answer D is incorrect because theread-only tag can be read by an interrogator, not just by the manufacturer.

58. A ground loop is an unwanted current that flows in a conductor connectingtwo points that are normally at the same ground potential,but are actually at different potential causing a current flow from thepoint with lower potential to the point with higher potential.

❑ A. This statement is true. ❑ B. This statement is false because a ground loop occurs when a building

is struck by lightning. ❑ C. This statement is false because a ground loop is a connection between

interrogators and a way it is attached to the ground. ❑ D. This statement is false because a ground loop results from current

flowing from the point with higher potential to the point with lower potential.

In reality, the two points are at what may appearto be the same potential but in reality are at different potentials.Current flow results from the point of higher potential to the lowerpotential point. Therefore, answers A, B, and C are incorrect.

59. Air interface protocol defines ❑ A. the rules of communications between the interrogator and the tag ❑ B. the tag architecture and the memory size available ❑ C. anti-collision algorithm as well as modulation and bit-encoding rules ❑ D. design rules for manufacturers of RFID devices

Air interface protocol does not specifythe tag architecture or memory size available, nor design rules formanufacturers of RFID devices; therefore, answers B and D are incorrect.

60. Back-end systems should be considered suspect of failure when ❑ A. tag data is not associated with a particular product it is attached to. ❑ B. the interrogator firmware load needs to be upgraded. ❑ C. EPC numbers are not being recognized as valid. ❑ D. products are deleted from inventory after being read.

Tag data is basically associated with adatabase record. If there are consistently no associations, then theconfiguration of the back-end system should be checked. Answer B isincorrect unless no tags are being read at all. Then it might be a hardwareor software (firmware) issue. When products are being deletedfrom inventory after being read, the back-end systems are not failing;therefore, answer D is incorrect.

61. Which of the following can provide a function of an antenna in an RFID tag? ❑ A. A coiled spring ❑ B. An induction frequency adapter ❑ C. An internal diode ❑ D. An induction coil

An induction coil used mainly in Low to HighFrequency tags is a passive electronic component that stores energy inthe form of a magnetic field. In its simplest form, an induction coilconsists of a wire loop or coil. The inductance is directly proportionalto the number of turns in the coil. Inductance also depends on theradius of the coil and on the type of material around which the coil iswound. Certain tags use antennas instead of the induction coil; theseare Ultra High Frequency tags. Answer A is not correct because tagsdo not have springs as part of their anatomy. Answer B is not correctbecause the term induction frequency adapter is not defined in RFID, and answer C is incorrect because the anatomy does not include aninternal diode.

62. Which international standard specifies the air interface communicationsat 860 to 960 MHz?

❑ A. ANSI NCTIS 256 ❑ B. ISO 18000 Part 2 ❑ C. ISO 18000 Part 6 ❑ D. EN 300 220 ❑ D. This statement is false because ESD is used to power interrogators.

ISO 18000 Part 6 specifies the air interface communicationsat a frequency band 860 to 960 MHz. Answer A is incorrectbecause ANSI NCTIS 256 is a standard for item managementthat describes three 2.4 GHz interfaces, 2 UHF interfaces, and the13.56 MHz interface. Answer B is incorrect, because ISO 18000 Part2 sets the parameters for air interface communications below 135 kHz.Answer D is also incorrect because EN 300 220 is provided by theEuropean Telecommunications Standards Institute (ETSI) and is notvalid internationally and specifies power, bandwidth and duty cycle.

63. Which of the following is/are characteristics of a passive tag? ❑ A. A passive tag usually has its own power source. ❑ B. A passive tag usually has a range of 100 feet or more. ❑ C. A passive tag generally draws all of its power from the radio waves

transmitted by an RFID reader. ❑ D. A passive tag uses beaconing to let the reader knows it is in its interrogation

zone.

Passive RF tags obtain operating power from theRF reader. They are smaller and lighter than active tags but have ashorter communication range and require a high-powered reader.Answer A is incorrect because passive tags usually do not have theirown power source. Answer B is incorrect because passive tags usuallydo not achieve such long read ranges; they vary from 1 inch up to 30feet. Passive tags do not have their own transmitter and so cannot beacon.Therefore, answer D is also incorrect.

64. In terms of RFID, what does the acronym WORM stand for? ❑ A. Write once, read many ❑ B. A virus that affects the tag’s data, making it read as 00001100 ❑ C. A program or algorithm that replicates itself over a computer network

and usually performs malicious actions, such as using up the computer’sresources and possibly shutting down the system

❑ D. Write many, read man

WORM means write once, read many times. Inaddition, WORM refers to both Class 0+ and Class 1 tags, whereClass 0+ is not an official tag classification. Answer B is not correctbecause, in terms of RFID technology, the data from a tag is not ableto interface directly with the back-end system. Answer C is not correctbecause this is an RFID term and does not refer to a virus. Althoughthe tags with WORM technology can be technically read and writtento many times, the official term, WORM, refers to write once, readmany. Therefore, answer D is incorrect.

65. Which of the following, if any, accurately describe what is meant by single dipole? ❑ A. An antenna with one connect point but multiple axes ❑ B. A single-axis antenna ❑ C. An array of antennas lined up in a criss-cross pattern ❑ D. Antennas that are overlapping ❑ E. None of the above

In the early days of RFID, tags were only singledipole. This means that there is essentially one antenna aligned on asingle axis. The resulting correlation of the tag to the field is themeaning of a single-axis antenna, or single dipole. For a field withspecific polarization, these types of tags must be aligned so that theyare parallel with the read field. For example, if linear antennas areused and are aligned horizontally, the tags must be horizontallyaligned and facing the antennas to read successfully. These tags workwell in manufacturing lines where the tag orientation and position canbe assured. Answer A is not correct because the term multiple refers tomore than one, and the question asks about a “single dipole.” Answer C is also incorrect because it refers to more than one antenna configuration.Answer D is not correct because like answer C, it refers tomore than one antenna configuration. Answer E is incorrect as well.

66. Part 15–compliant interrogators can operate at a maximum transmittedpower of 1 watt or up to ____ watts with a gained antenna.

❑ A. 2 ❑ B. 4 ❑ C. 6 ❑ D. 100

The maximum allowed level of power withgained antenna is 4 watts. Therefore, answers A, C, and D are incorrect.

67. Divert gates are most often used to ❑ A. divert products that have bar codes. ❑ B. separate HF-tagged products from UHF-tagged products. ❑ C. divert products with invalid tags off a production line. ❑ D. divert interrogator signals.

Divert gates can be configured todivert products with bar codes, separate HF-tagged products fromUHF-tagged products, or divert products with invalid tags off a productionline. Divert gates do not divert interrogator signals; therefore,answer D is incorrect.

68. Which of the following organization’s safety rules and regulations haveto be followed when installing RFID systems in facilities in the US?

❑ A. World Health Organization (WHO) ❑ B. Occupational & Safety Administration (OSHA) ❑ C. EPC global ❑ D. Office of Telecommunications Authority (OFTA)

The Occupational & Safety Administration orOSHA is responsible for employee and facility safety in the US. AllRFID installations in the US need to comply with OSHA regulations.Answer A is incorrect because the World Health Organization producesonly recommendations and it is up to each individual country toenforce these recommendations as a law and penalize non-compliance.Answer C is incorrect, because EPCglobal does not govern installationsafety. Answer D is also incorrect; the Office of TelecommunicationsAuthority (OFTA) is a government organization in Hong Kong anddoes not have jurisdiction over the US.

69. What are the current EPC classes? ❑ A. Class 0 ❑ B. Class 1 ❑ C. Class 1, Generation 2 ❑ D. All of the above ❑ E. None of the above

EPC classes include Classes 0 and 1, which pertainto passive tags. Generation 1, Class 0 is read-only; Class 1 is writeonce, read many (WORM). EPC also defines Class 1, Generation 2for passive tags, which are fully rewritable.

70. What is a Faraday Cage? ❑ A. A cage to hold Faraday birds ❑ B. A system to control radiated signals by containing them or shielding

from them, and in most cases both are achieved ❑ C. A set of trigger panels configured into a circle ❑ D. None the above

A Faraday Cage is an electrical apparatusdesigned to prevent the passage of radiated signals and waves by eithercontaining them in or excluding them from its interior space. It isnamed for physicist Michael Faraday, who built the first one in 1836.Answer A is not correct and is a fictitious reply. Answer C is not correctbecause the question refers to antenna configuration, not triggeringdevices. Answer D is incorrect by default.

71. Why do passive HF tags have a relatively shorter read range comparedto passive UHF tags?

❑ A. Passive HF tags have a smaller antenna than UHF tags; therefore theyhave shorter read range.

❑ B. Passive HF tags use inductive coupling that utilizes a magnetic fieldthat is propagated only in short distances within the allowed powerparameters.

❑ C. Passive HF tags utilize an electric field that in conjunction with theirinduction coil allows only for a short read range.

❑ D. Passive HF tags have shorter read range because of their ASIC chipdesign.

Answer A is incorrect because the size of theantenna usually increases with decreasing frequency due to the relationshipbetween the wavelength and antenna size. The read rangedepends on communication method and power, not on the size of tag’santenna. Answer C is incorrect, passive HF tags utilize a magneticfield and not an electric field. Answer D is also incorrect. The readrange for passive HF tags depends on the method of energy transferand communication and generally not on the chip design.

72. What is passive backscatter? ❑ A. The term is used to describe how one interrogator sends a signal to

another interrogator. ❑ B. A reader sends out an RF signal, and then a tag replies to the signal by

breaking up the signal into ones and zeros. ❑ C. A tag that has the substrate removed, allowing the radiated signal to

bounce around. ❑ D. All of the above.

UHF and microwave passive tags have antennas(as opposed to having an induction coil) and communicate with areader using passive backscatter (also called modulated backscatter).The reader transmits a continuous-wave RF signal into the readingenvironment. When a tag appears in the area, it receives the signaland modulates (or breaks up) the RF signal into patterns of ones andzeros that define the tag’s digital data while reflecting it back to thereader. Answer A is not correct because the passive backscatter refersto interrogator/tag communication. Answer C is not correct becausepassive backscatter refers to the signal to and from the interrogator,not the materials used to create the tag. Therefore, answer D is incorrect.

73. What are interrogation tunnels? ❑ A. Places where people are questioned ❑ B. Arrays of antennas fixed in a tunnel shape to allow for accurate reads

no matter the orientation of the package traveling through the tunnel ❑ C. An array of antennas at a dock door portal ❑ D. All of the above

Interrogation tunnels are structures placed overconveyor roller assemblies that provide a convenient and efficientmeans for high-performance antennas to be fixed. The best design fora tunnel antenna allows the reader’s energy field to be uniformly radiated.A homogeneous radiation pattern enables the reader to interrogatetags regardless of their relative orientation. Answer A is notcorrect because it is a fictitious reply. Answer C is not correct becausethis option refers to an array on a dock door, which is referred to as aportal, not a tunnel. Consequently, answer D is incorrect as well.

74. Define front-to-back ratio? ❑ A. When a radiated signal is focused into a beam, the signal has a diffraction

effect, causing some of the signal not to be focused. This diffractedsignal does, in fact, bounce back into the antenna.

❑ B. The size of the reflector * the power used to generate a signal. ❑ C. The beam shape as it is directed to the focal point. ❑ D. None of the above.

Front-to-back ratio is defined as when a doughnutradiation pattern is achieved, and it is squeezed into a beam off thefront of the antenna. The reflector used for focusing the beam doesnot stop all the radiated energy, and some is radiated toward the rear(or, in the case of reception, bypasses the reflector and is interceptedby the dipole). The tips of the metal cause some signals to “bend” onthe edges of the reflector and toward the rear (or, in the case of reception,from the rear toward the dipole). Answer B is not correctbecause the question asks you to define a term, and this answer definesa formula. Answer C is not correct because the term defines how thebeam moves, not the shape as it is transmitted. Consequently, AnswerD is incorrect as well.

75. If you were tagging a case of ketchup bottles that will be traveling ona conveyor, where would you place the RFID tag?

❑ A. On the bottom of the case avoiding barcodes. ❑ B. On one of the sides of the case avoiding barcodes and manufacturer’s logos. ❑ C. On the top of the case anywhere. ❑ D. On the top of the case, avoiding manufacturer’s logos or barcodes.

When tagging any product, care shouldbe given not to cover any barcodes or manufacturer logos or marketingmaterial. Answer A is incorrect. Conveyors usually have metalrollers, which would pose a problem for reading the tag from thebottom. Since ketchup is liquid and any antenna trying to read the tag from the top would have to penetrate through the ketchup, placingthe tag on the bottom of the case would not work either. Answer C isalso incorrect. When tagging a product you should not just place thetag anywhere, but you should avoid logos, barcodes and other thingsthat are identifying components on the packaging.

76. What does modulation mean? ❑ A. Changing the number of boxes that go through a reader ❑ B. Changing the properties of the radio waves ❑ C. Making adjustments to the conveyor belt to speed the boxes ❑ D. None of the above

Modulation means changing the properties of theradio waves traveling between the reader and the transponder in waysthat enable the transmission of information. Radio waves can bechanged in a variety of ways that can be picked up by the reader andturned into zeros of binary code. Answer A is not correct because thequestion refers to the radio waves, not the number of tagged itemsmoving through the interrogator. Answer C is not correct because thequestion does not refer to the speed that a tagged item is movingacross the system. Consequently, answer D is incorrect as well.

77. Which of the following is/are components of an RFID tag? ❑ A. Antenna/induction coil ❑ B. Silicon chip ❑ C. Modulation circuitry ❑ D. Nonvolatile memory ❑ E. All of the above

An RFID tag is composed of an antenna/inductioncoil and a silicon chip that includes basic modulation circuitry andnonvolatile memory. The RFID tag is energized by a time-varyingelectromagnetic radio frequency (RF) wave that is transmitted by theinterrogator. The radiated signal is called a carrier signal. When theRF field passes through the antenna coil, an AC voltage is generated,activating the coil. This voltage is rectified to supply power to the tag.The information stored in the tag is transmitted back to the interrogator.

78. From the following choices, what key difference or differences arethere between RFID and bar-code technology?

❑ A. RFID eliminates the need for line-of-sight reading that bar coding depends on. ❑ B. RFID scanning can be done at greater distances than bar-code scanning. ❑ C. All RFID devices are able to identify only RF tags, and bar-code devices are able to

identify only bar codes. ❑ D. RFID requires a line of sight.

Some of the key differences betweenRFID and bar-code technology are that RFID technology eliminatesthe need for line-of-sight reading that bar coding depends on. In addition,RFID scanning can be done at greater distances than bar-codescanning. Ultra High Frequency RFID systems (850 MHz to 950MHz and 2.4 GHz to 2.5 GHz) offer transmission ranges of morethan 90 feet. Answer C is incorrect because some of the RFID interrogatorsare also capable of reading bar codes (mainly the handhelddevices). RFID does not require a line of sight; therefore, answer D isincorrect.

79. What is the difference between time required to read a tag and write to tag? ❑ A. The time to read the tag and write to tag is approximately the same. ❑ B. It takes longer to read the tag than write to tag. ❑ C. The time to write to tag is approximately 110% of the time to read the tag. ❑ D. The time to write the tag is about 5 times longer than the time to read the tag.

It takes longer to write to tag than read the tag;therefore, answers A and B are incorrect. It takes about 150 to 170%of a read time to write to tag; therefore, answer C is also incorrect.

80. Which of the following is/are characteristics of a semi-passive tag? ❑ A. A semi-passive tag functions sometimes as passive and sometimes as

active. ❑ B. A semi-passive tag uses a battery to run the microchip’s circuitry but

not transmit information to the RFID reader. ❑ C. A semi-passive tag is an RFID tag that cannot be used for capturing

additional data, such as temperature of the environment. ❑ D. A semi-passive tag can beacon.

Semi-passive tags use a battery to run themicrochip’s circuitry but not to communicate with the RFID reader.They contain a power source, such as a battery, to power themicrochip’s circuitry. Unlike active tags, semi-passive tags do not usethe battery to send the signal to the interrogator. Some semi-passivetags are dormant until activated by a signal from a reader. This conservesbattery power and can lengthen the life of the tag. Answer A isincorrect because semi-passive tags use a passive communication technique(inductive coupling, passive backscatter) and do not have theirown transmitter. Therefore, answer D is also incorrect. This isreserved for the active tags. Answer C is incorrect because semipassivetags can carry various sensors on board that capture informationabout the outside environment.