2m Amateur Radio Satellite Egg Beater Omni-Directional Antenna

grabcad

This is a model of a 2 meter (133 ~ 150 MHz) Amateur Radio Satellite Egg Beater Omni-Directional Antenna for communications to the up-facing coverage of Low Earth Orbit AMSAT / OSCAR satellites. This antenna is sold by M^2 as the EB-144 and comes with the optional reflector kit RK-2M and is described as :"The EB-144 EGGBEATER offers exciting new performance characteristics for both fixed and mobile operations. The EGGBEATER produces smooth omnidirectional HORIZONTAL polarity at the horizon. Above the horizon, the pattern transforms to RIGHT HAND CIRCULAR, making it a natural for OSCAR satellite use. By spacing the EGGBEATER 1/8 wave above a metal surface or adding the RK-2M Reflector kit, now standard, for base installations, the circular lobe increases by 6 dB, producing a hemispherical pattern. No rotation or steering is required. For terrestrial mobile, base, net control, contest or field day operation, increasing the distance above ground or over a metallic surface improves the horizontal radiation by 6 dB. This produces instantaneous communications in all directions. Hams with little room or budget for larger antennas will experience a new standard of performance with the EB-144/RK2M." from their website here :https://www.m2inc.com/FGEB144RK2MNote that the black center fiberglass rod is non-conductive and is NOT a radiating or receiving element of the antenna, it is simply a support for the loops and is not required for heavier gauge wire or other tubing for the loops.There is a performance review of this antenna here : https://antennatestlab.com/antenna-examples/example-10-eggbeater-leo-satellite-antenna-for-432-mhz-70cmAnd there is an article on this antenna as part of a pair for satellite communications as part of M^2 sat-pack : https://www.k5nd.net/2018/12/m2-eggbeater-sat-pack/'Egg Beater' antennas are simply (2) loop antennas that are interposed at 90 degrees to each, since a loop reception has a null towards the outside in the lane of the loop, so with (2) at right angels will cover the full 360 degrees. They are Omni-Directional type of antennas and therefore are good general receiving antennas, but do not have high gain for sensitive communications. For a high gain (directional) antenna either a dish, yagi, cubical, or other multiple element antenna is necessary.https://en.wikipedia.org/wiki/Loop_antennaAn option for this antenna would be mesh screening layed on top of the ground radials as shown in this paper here : https://on6wg.pagesperso-orange.fr/Doc/Antenne%20Eggbeater-Engl-Part1-Full.pdf. Notice that the ground counterpoise radials are flat and not angled downwards in the Vertical Ground Plane Antenna that i modeled earlier. This is because having a flat ground (plane) close to the radiating element will push up the radiation pattern (also known as the take-off angle) towards to sky, which for space communications is desirable. For terrestrial (land) based antennas we typically do not want a steep take-off angle and therefore the counterpoise elements are angled downwards.And for a much more exotic dual version, take a look at this 2m / 70cm dual egg beater with the 70cm inside of the 2m antenna : https://amsat-uk.org/2020/12/29/video-of-dual-band-eggbeater-antenna-talk/