3_Waveguide Based Devices

8/3/2019 3_Waveguide Based Devices

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The waveguide components generallyencountered are:

Tee junctions

E-plane, H-plane &Magic Tee

Attenuators

Directional couplers Waveguide terminating devices

Slotted sections


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Components that reduce the amount of power a fixedamount, a variable amount or in a series of fixed stepsfrom the input to the output of the device.

Operate on the principle of interfering with the electricfield or magnetic field or both.Slide vane attenuators: a resistive material placed in

parallel with the E-lines of a field current will induce acurrent in the material that will result in I2Rpower loss.

Flap attenuator: has a vane that is dropped into thewaveguide through a slot in the top of the guide. Thefurther the vane is inserted into the waveguide, thegreater the attenuation.

Rotary vane attenuator: It is a precision waveguide

attenuator & attenuation is independent on frequency.


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provides a termination designed to absorb allthe incident power with very little reflection,

effectively terminating the line or port in itscharacteristic impedance.


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Waveguide Tees

Cutting arectangular slotalong the width

of the mainwaveguide &attachinganother

waveguide

H-plane Tee

Main arm

H-arm /side arm

Port 3

Port

1

Port 2

Collinear ports


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Axis of the side arm is parallel to the plane ofthe main TL

All the 3 arms lies in the plane of magnetic fieldmagnetic field divides itself into the armsCURRENT JUNCTION

When TE10

mode is allowed to propagate intoport 3, the electric fields do not change theirdirection when coming out of port 1 & 2 Hplane tee


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S-matrix of H-plane Tee

S13 = S23 due to plane ofsymmetry at the junction

Symmetric propertyS12 = S21S23 = S32 = S13S13 = S31 Perfect match at the junction

S33 = 0

333231

232221

131211

SSS

SSS

SSS

S

01313

132212

131211

SS

SSS

SSS

S


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Unitary property [S] [S] * = [ I ]

100

010

001

0**

***

***

0 1313

132212

131211

1313

132212

131211

SS

SSS

SSS

SS

SSS

SSS

21)(

11

1***)(

213

222

21222

213

212

211

13131212111111

SSSCR

SSS

SSSSSSCRfrom (1) & (2)|S11|

2 = |S22|2

S11 = S22 (3)


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52

1,12

41)(

13

2

13

213

21333

SS

SSCR

70**

0

0**

60**)(

1211

1211

13

121113

1213111313

SS

SS

S

SSS

SSSSCR


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Using (3,5,7) in (1)

92

1

82

1

2

12

12

1

12

11

2

11

2

11

2

11

S

S

S

SS

102

122 S

02

1

2

12

1

2

1

2

12

1

2

1

2

1

S


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3

2

1

3

2

1

02

1

2

121

21

21

2

1

2

1

2

1

a

a

a

b

b

b

aSb

213

3212

3211

2

1

2

1

2

1

2

1

2

1

2

1

2

1

2

1

aab

aaab

aaab


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0

2

2

0,0,0)1(

3

32

31

213

b

ab

ab

aaaa3 power input at port 3

Power gets equally divided

b/n the ports (1) & (2)

P3 = P1+P2=2 P1=2P2Amount of power coming out of port 1 or 2 due to i/p at port 3

dBP

P

P

P3

2

1log10log10log10

3

2

3

1 3 dB Power splitter


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2222

0222

0222

0,)2(

213

3212

3211

321

aaaab

aaab

aaab

aaaa

Power output at port 3 is

addition of power inputs from(1) & (2) in phaseH arm is

also called SUM ARM


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Waveguide Tees

Cutting arectangular slotalong the

broaderdimension ofthe main

waveguide &attachinganother

waveguide

E-plane Tee

H-arm /side arm

Main arm

Port3

Port

1

Port 2

Collinear ports

Port 1

Port 2

Collinear ports

Port 3E arm


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S-matrix of E-plane Tee

S13 = -S23 due to plane ofsymmetry at the junction & o/p

180

out of phase Symmetric property

S12 = S21S23 = S32 = -S13S13 = S31 Perfect match at the junctionS33 = 0

333231

232221

131211

SSS

SSS

SSS

S

01313

132212

131211

SS

SSS

SSS

S


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Unitary property [S] [S] * = [ I ]

100

010

001

0**

***

***

0 1313

132212

131211

1313

132212

131211

SS

SSS

SSS

SS

SSS

SSS

21)(

11

1***)(

213

222

21222

213

212

211

13131212111111

SSSCR

SSS

SSSSSSCRfrom (1) & (2)|S11|

2 = |S22|2

S11 = S22 (3)


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52

1,12

41)(

13

2

13

213

21333

SS

SSCR

7

0

0**

60**)(

221211

13

121113

1213111313

SSS

S

SSS

SSSSCR


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Using (3,5,7) in (1)

92

1

82

1

2

12

12

1

12

11

211

2

11

2

11

S

S

S

SS

102

122 S

02

1

2

12

1

2

1

2

12

1

2

1

2

1

S


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3

2

1

3

2

1

02

1

2

121

21

21

2

1

2

1

2

1

a

a

a

b

b

b

aSb

213

3212

3211

2

1

2

1

2

1

2

1

2

1

2

1

2

1

2

1

aab

aaab

aaab


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0

2

2

0,0,0)1(

3

32

31

213

b

ab

ab

aaaa3 power input at port 3

Power gets equally divided

b/n the ports (1) & (2) with a

phase difference of 180E plane tee 3 dBPower splitter


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0

22

22

0,)2(

3

2

1

321

b

aab

aab

aaaa

Power output atport 3 is zero with

equal inputs at

port 1 & 2

2

2

2

0,0,0)3(

13

12

11

321

ab

ab

ab

aaa


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H-arm

E-arm

Port1

Port2

Port3

Port4

00

00

1414

131314132212

14131211

SS

SS

SSSS

SSSS


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H-plane Tee section S23 = S13 E-plane section S24 = -S14 Geometry of the section S34 = S43 = 0

Symmetric propertyS12 = S21S23 = S32S13 = S31S

24

= S42S43 = S34

S14 = S41 Port 3 & 4 matched S33 = S44 = 0

00

00

1414

1313

14132212

14131211

SS

SS

SSSS

SSSS


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1000

0100

0010

0001

00**

00**

****

****

00

00

1414

1313

14132212

14131211

1414

1313

14132212

14131211

SS

SS

SSSS

SSSS

SS

SS

SSSS

SSSS

3

21)(

11)(

2211

2

14

2

13

2

22

2

1222

214

213

212

21111

SS

SSSSCR

SSSSCR


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80

0

121

21

1211

2

12

2

11

212211

SS

SS

SS

Using (3,5,7) in (1)

52

1

41)(

13

213

21333

S

SSCR

721

61)(

14

214

21444

S

SSCR

002

1

2

1

002

1

2

12

1

2

100

2

1

2

100

S


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Four port waveguide junctionPrimary waveguide 1-2Secondary waveguide 3-4


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With matched terminations at all the ports, propertiesof ideal DC

1. Portion of power travelling from port 1 to port 2 is

coupled to port 4 not to port 3.2. Portion of power travelling from port 2 to port 1 iscoupled to port 3 not to port 4.

3. Portion of power incident at port 3 is coupled toport 2 but not to port 1

4. Portion of power incident at port 4 is coupled toport 1 but not to port 2

5. Ports 1 &2 are decoupled as are ports 2&4


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Coupling Factor C Directivity D Isolation I

dBP

PD

b

f

10log10

Piincident power at port1Prreceived power at port2Pfforward coupled power at port4

Pbback power at port3

dBP

PI

b

i

10log10

dBP

PC

f

i

10log10

)()()( dBDdBCdBI


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All ports are perfectly matched S12 =S22 = S33 =S44 =0 Symmetric property

S23 = S32, S13 = S31,S24 = S42,S43 = S34,S14 = S41 No coupling b/n port 1 & 3 S13 = S31 = 0 No coupling b/n port 2 & 4 S24 = S42 = 0

00

0000

00

3414

3423

2312

1412

SS

SSSS

SS


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1000

0100

0010

0001

0*0*

*0*0

0*0*

*0*0

00

00

00

00

2314

3423

2312

1412

2314

3423

2312

1412

SS

SS

SS

SS

SS

SS

SS

SS

321)(

11)(

2314

21321222

214

21211

SS

SSCR

SSCR


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1234

234

214

234

22333

1)3(

41)(

SS

SS

SSCR

from

343412

12

12

*SPSS

PS

S

ve&realasAssume


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jySjyS

SSPSSP

PSPS

SSSSCR

2323

2323

2323

2323

3414231231

*,

0*,00*

0*

0**)(

1221423

3412

1423

QP

jQSS

PSS

SjQSLet

00

00

00

00

PjQ

PjQ

jQP

jQP

3_Waveguide Based Devices

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