EH Antennas for Hams September 2004 by Ted Hart W5QJR Courtesy of EH Antenna Systems.
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Transcript of EH Antennas for Hams September 2004 by Ted Hart W5QJR Courtesy of EH Antenna Systems.
EH Antennasfor Hams
September 2004by
Ted Hart W5QJR
Courtesy ofEH Antenna Systems
What Is An EH Antenna?
It is a revolutionary concept that It is a revolutionary concept that allows allows smallsmall antennas to outperform antennas to outperform
largelarge antennas. antennas.
EH Antenna – An ExampleLocated at Eatonton, Georgia
What Are The Defining ParametersOf An EH Antenna?
___________________________________________________________________________________________________
» Small Size
What Are The Defining ParametersOf An EH Antenna?
___________________________________________________________________________________________________
» Small Size»+ Low Height
What Are The Defining ParametersOf An EH Antenna?
___________________________________________________________________________________________________
» Small Size»+ Low Height »+ No Radials Required
EH ANTENNAS ARE DIPOLES
A 20 Meter EH Antenna
What Are The Defining ParametersOf An EH Antenna?
___________________________________________________________________________________________________
» Small Size»+ Low Height »+ No Radials Required »+ Broad Bandwidth
What Are The Defining ParametersOf An EH Antenna?
___________________________________________________________________________________________________
» Small Size»+ Low Height »+ No Radials Required »+ Broad Bandwidth »+ High Efficiency
What Are The Defining ParametersOf An EH Antenna?
___________________________________________________________________________________________________
» Small Size»+ Low Height »+ No Radials Required »+ Broad Bandwidth »+ High Efficiency»+ Low EMI
What Are The Defining ParametersOf An EH Antenna?
___________________________________________________________________________________________________
» Small Size»+ Low Height »+ No Radials Required »+ Broad Bandwidth »+ High Efficiency
__________________________________________________________________________________________________________
»= A Great Antenna for Hams
»+ Low EMI
The Number 1 Question,does It Work?
* FCC Type tests prove it is a very good AM Broadcast Antenna
* Many Hams use home made EH Antennas
*Companies in Italy and Japan manufacture EH Antennas for Hams
*EH Antennas are in commercial use
* EH Antennas will be the preferred choice in the future for most communications applications
QUESTION #2 – HOW DOES IT WORK?
E FIELD
H FIELD
HIGH CURRENT
The Evolution Of The EH AntennaL+L NETWORK
C1
C2
L1
L2
Phasing Coil
Coax
The Evolution Of The EH AntennaL+T NETWORK
Coax
C1 C2
L1 L2
Phasing Coil
The Evolution Of The EH Antenna *STAR* EH ANTENNA
COAX
CYLINDER
TUNING COIL
PHASING COIL
CYLINDER
REACTANCE COIL
EH Antenna Analysis Programx Frequency - Mhz - - - - - - - - - - -3.900x Transmitter Power - Watts - - - - - -1000x Antenna Diameter - Inches - - - - - -3.3x Cylinder Length/Diameter Ratio - - - - - - - - 12x Measured Effective 3 dB Resistance - Ohms - - -
Radiation Resistance - - - - - - - - -
EH Antenna Analysis ProgramMeasuring 3 dB Resistance
Definition - - - Q=XL/R=F0/BW
Therefore: R = BW*XL/ F0
Radiation Resistance = 3 dB Resistance – Loss Resistance
EH Antenna Analysis Programx Frequency - Mhz - - - - - - - - - - -3.900x Transmitter Power - Watts - - - - - -1000x Antenna Diameter - Inches - - - - - -3.3x Cylinder L/D Ratio - - - - - - - - 12x Measured Effective 3 dB Resistance - Ohms - - -56
Radiation Resistance - - - - - - - - -54.20
EH Antenna Analysis ProgramCylinder Capacity - pFd - - - - - - -28Shunt capacity - pFd - - - - - - - -22Effective Inductive Reactance - ohms - - -8133 dB Bandwidth - KHz - - - - - - -269Effective Antenna Q - - - - - - - - -15Tuning Inductance - uHy - - - - - - - -33Circulating current - amps - RMS - - - -4.3Cylinder voltage - volts -RMS - - - - - - 3490
C = 0.55*L/D*D + 2.06*D
EH Antenna Analysis ProgramPhasing coil length (6 degrees). 4
x Effective wire diameter - inches 0.06Heat loss - watts - - - - -2.38
EH Antenna Analysis ProgramTuning Coil details
x Diameter - inches - - - - - - - - -3.3x Pitch - inches (center to center) - - - - -0.064
Coil Length - inches - - - - - - - - -1.2Coil Turns - - - - - - - - - - - - 18.0
x Effective wire diameter - inches - - - - - - - 0.06Wire length - feet - - - - -71.0Heat loss - watts - - -40.06
EH *STAR* ANTENNA
COAX
CYLINDER
TUNING COIL
PHASING COIL
CYLINDER
REACTANCE COIL
ROLL YOUR OWN EH ANTENNA
• STEP 1- OBTAIN TEST EQUIPMENT
• SIGNAL GENERATOR
– FIELD STRENGTH METER
– VSWR BRIDGE
– IMPEDANCE BRIDGE (NICE)
PREFERRED TEST EQUIPMENT
ROLL YOUR OWN EH ANTENNA
• STEP 2 – BUILD COAX CHOKE
ABOUT 1/8 WAVELENGTH OF COAX WOUND IN A COIL
LOCATE ABOUT 3 FEET BELOW THE ANTENNA
COAX CHOKE
ROLL YOUR OWN EH ANTENNA
STEP 3 - ASSEMBLE THE ANTENNA DO NOT TRY TO MAKE THE FIRST
ONE PRETTY –USE ALUMINUM FOIL OVER PLASTIC PIPE
USE 2 TURN FEED TAP –
NO SOURCE COIL YET
75 METER EH ANTENNA
ROLL YOUR OWN EH ANTENNA
STEP 4 A - TUNE THE ANTENNA
MEASURE OPERATING FREQUENCY WITH FIELD STRENGTH METER –
TAP TOP OF TUNING COIL TO CHANGE FREQUENCY
75 METER TUNING COIL
ROLL YOUR OWN EH ANTENNA
STEP 4 B - TUNE THE ANTENNA
PLOT IMPEDANCE or COMPARE MAX RADIATION AND MINIMUM VSWR FREQUENCIES
IMPEDANCE WITHOUT REACTANCE COIL
R- X- VSWR*50 - MAX RADIATION
-150
-100
-50
0
50
100
150
200
3.700 3.800 3.900 4.000 4.100 4.200
FREQUENCY - MHz
NU
ME
RIC
ROLL YOUR OWN EH ANTENNA
STEP 4 - TUNE THE ANTENNA
C – INSTALL SOURCE COIL
D – ADJUST FEED FOR 50 OHMS
E – RECORD IMPEDANCE PLOT
IMPEDANCE WITH REACTANCE COIL
• 3 dB Bandwidth = 269 KHz
R - X - VSWR*10
-30.0-20.0-10.00.010.020.030.040.050.0
3.800 3.850 3.900 3.950 4.000 4.050 4.100
FREQUENCY - MHz
NU
ME
RIC
EH Antenna Analysis ProgramTotal Heat loss - watts - - - - - - - -45.27Antenna System Efficiency - Percent - - - - - -95.47Antenna System Efficiency - dB - - - - - --0.20
HEIGHT VS. RADIATION ALONG THE GROUND.
RADIATION LEVEL vs. HEIGHTComparison of EH Antenna
to a standard 1/4 wavelengthAM Broadcast antenna
-6.00
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
0.00 0.05 0.10 0.15 0.20 0.25 0.30
HEIGHT ABOVE GROUND - WAVELENGTHS
RE
LA
TIV
E G
AIN
- d
B
WEB SITE
• www/eh-antenna.com