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A batwing or super turnstile antenna is a broadcasting antenna used at VHF and UHF frequencies, named for its distinctive shape resembling a bat wing or bow tie. Stacked arrays of batwing antennas are used as television broadcasting antennas due to their omnidirectional characteristics. Batwing antennas generate a horizontally polarized signal. The advantage of the "batwing" design for television broadcasting is that it has a wide bandwidth. It was the first widely used television broadcasting antenna.
To reduce power radiated in the unwanted axial directions, in broadcast applications multiple bays fed in phase are stacked vertically with a spacing of approximately one wavelength, to create a collinear array. This generates an omnidirectional radiation pattern with increased horizontal antenna gain (more of the energy radiated in horizontal directions and less into the sky or down at the earth), suitable for terrestrial broadcasting.
The "batwing" shape of the elements is adapted from the butterfly antenna (a flattened biconical antenna), used because it gives the antenna a wide bandwidth of approximately 20% of operating frequency at a VSWR of 1.1:1. This makes the antenna design suitable for broadcasters who wish to use a single antenna to transmit multiple television signals and thus made the batwing the preferred antenna for lowband TV stations (Band I; channels 2–6) in the early days of broadcast television.
See also
Sources
(1993). 9780442015947, Springer. ISBN 9780442015947
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