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/FGEB144RK2M
Note 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-70cm
And 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_antenna
An option for this antenna would be mesh screening layed on top of the ground radials as shown in this paper here : https...
What balun is that?
its a custom BalUn to match the antenna to a 50 ohm coax. - - you can contact M^2 for specific information about the BalUn.
Anytime you see this antenna it is sure to be used for satellite communications !
This antenna is particularly useful for roving satellites ! - - If there is any other antennas that you wish to see, be sure to let me know. Thanks !