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


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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


___________________________________________________________________________________________________

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


___________________________________________________________________________________________________

» 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


• 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

NU

ME

RIC


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

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.