EH Antennas for Hams

EH Antennasfor Hams

September 2004by

Ted Hart W5QJRCourtesy 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?

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» Small Size


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» Small Size»+ Low Height


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» Small Size»+ Low Height »+ No Radials Required

EH ANTENNAS ARE DIPOLES

A 20 Meter EH Antenna


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» Small Size»+ Low Height »+ No Radials Required »+ Broad Bandwidth


___________________________________________________________________________________________________

» Small Size»+ Low Height »+ No Radials Required »+ Broad Bandwidth »+ High Efficiency


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» Small Size»+ Low Height »+ No Radials Required »+ Broad Bandwidth »+ High Efficiency»+ Low EMI


___________________________________________________________________________________________________

» Small Size»+ Low Height »+ No Radials Required »+ Broad Bandwidth »+ High Efficiency

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»= 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


• STEP 2 – BUILD COAX CHOKE

ABOUT 1/8 WAVELENGTH OF COAX WOUND IN A COIL

LOCATE ABOUT 3 FEET BELOW THE ANTENNA

COAX CHOKE


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


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


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

NUM

ERIC


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

NUM

ERIC

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

RELA

TIVE

GAI

N - d

B

WEB SITE

• www/eh-antenna.com

EH Antennas for Hams

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