Unidirectional, dual-whip E-field antenna

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Joined: Thu Oct 13, 2022 7:49 am

Unidirectional, dual-whip E-field antenna

Post by qrp-gaijin »

I'm glad to see that there is interest in in the other thread about discussing Villard's old Coplanar Twin Loop Antenna, which generates a "magnetic field shadow" resulting in a unidirectional null.

Villard also proposed and tested a dual-whip antenna system that uses an analogous "electric field shadow" effect to achieve directional discrimination, which I think also achieves a unidirectional null.

First, let's read Villard's brief explanation and warning about this kind of directional whip antenna.

http://web.archive.org/web/201912071150 ... ml/bg7.png
Antennas based on an electric-field analogue of the CTL's magnetic-field shadow are possible (see Figures 14, 15, and 16 of Reference 3). Designs based on this principle have attractive features; for example, with battery-operated receivers using whips, no connection between antenna and receiver is required. However, in view of their sensitivity both to hand capacity and to weak reflections (for example, from the body), they have not been developed further.
So -- directional discrimination with whip antennas, using nulls in the ambient electric field, is possible, but such antennas will be difficult to adjust due to hand capacitance and weak reflections.

OK, enough about the warnings -- how does one make such an antenna? Information is almost non-existent, but over the years I was able to find the following articles.

1. A description of the antenna, with an image of the antenna: "Anti-Jamming Antenna 1" at https://www.swradioafrica.com/Documents ... tennae.htm .

2. Another description, by Villard himself, of the antenna, but with no images: "Antenna for reducing
skywave interference, By Dr. O. G. Villard, Jr.". Warning: Ignore images at the bottom of the article, because they describe an unrelated loop antenna, not the dual-whip antenna. http://www2.hard-core-dx.com/nordicdx/a ... ucin1.html .

I have neither simulated nor built this antenna; because Villard decided to stop development on this antenna, I didn't want to invest too much time in this E-field antenna, and instead am more interested in the H-field CTL antenna. Nevertheless, this E-field dual-whip antenna may be useful in some circumstances. I would be happy to hear about the results if anyone tries this antenna.
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