The design principle of the EH antenna has be
discussed (often controversely) for some years. After many practical tests and
positive findings of many amateurs these antennas are now available in a
professional version for the ham radio sector.
EH antennas work differently than the known principle of the Hertz dipole. WIth
a traditional Hertz dipole the E and H field components are not in phase, this
effects that the radiation field is not properly built up until some distance
(>1 wavelength). An EH antenna uses a phasing network to align the phase of both
E and H field components, thus leading to a radiation field which is built up
much faster and closer to the antenna. The net result are much smaller antennas
with an effectiveness comparable to a usually larger dipole. Typical sizes are
2-3% of the wavelength.
EH antennas are mono band antennas, due to the design the entire band can
be used. With it's compact sizes the antennas can be easily used in space
restricted environments, especially on the low bands like 80 and 160m.
Additionally these antennas are comparatively quiet, reducing the often strong
noise level on these bands.
The radiation pattern is not published by the manufacturer at this time. EH
antennas are vertical antennas, so the azimuth diagramm is similiar to any omni
directional antenna. The elevation diagram is comparable to that of any
traditional vertical antenna, e.g. a quarter wavelength radiator with a gain of
0 to +2 dBD.
The connector is a PL female jack on the side of the antenna. The feedline is 50
Ω, an antenna tuner is not required. Mounting hardware is provided for mast
mounting.
To adjust the center frequency a simple alignment is possible. A copper belt can
be adjusted in height on the antenna, influencing the center frequency on the
band. A simple SWR meter is
sufficient for this adjustment.
| Model | Aspis | Cobra | Venus | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Band | 6 | 11 | 10 | 11 | 12 | 15 | 17 | 20 | 30 | 40 | 80 | 160 |
| Length [cm] | 66 | 68 | 90 | 93 | 248 | |||||||
| Diameter [cm] | 8 | 12,5 | 8/12,5 *1) | |||||||||
| Weight [g] | 1300 | 1500 | 3500 | 4900 | ||||||||
| Max.Power (SSB) [W] | 300 | 600 | 2000 | |||||||||
| Max.Power (FM) [W] | 75 | 150 | 500 | |||||||||
| Max. Mast diameter [mm] | 40 *2) | 35 | 40 *2) | |||||||||
*1) The 80m and 160m models have a diameter
of 8cm Durchmesser, at the lower end a thicker part of about 12,5 cm diameter.
*2) The 40mm clamps can be extended to 50mm by removing one of the brackets.
| Aspis-6 | 169,- | ||
| Aspis-11 | 119,- | ||
| Cobra-10 | 169,- | ||
| Cobra-11 | 169,- | ||
| Cobra-12 | 169,- | ||
| Cobra-15 | 169,- | ||
| Cobra-17 | 169,- | ||
| Cobra-20 | 169,- | ||
| Cobra-30 | 169,- | ||
| Cobra-40 | 169,- | ||
| Venus-80 | 305,- | ||
| Venus-160 | 305,- |
The smaller version of the 'Cobra 11' with astonishing specs: Length only 68cm,
frequency range 26,5 to 28MHz, wide bandwidth
of approx. 2MHz at a SWR of 2:1 or better. Max.
power load 600 Watt SSB/CW, 150 Watt AM/FM. |
 |
| Aspis-11 | 119,- |