English: Probably the first turnstile antenna array, constructed in 1936 on the roof of the Statler Hotel, Buffalo, New York, for experimental "ultra short wave" AM station
W8XH which broadcast on 41 MHz for a few years. The
turnstile antenna was invented by engineer George Brown at RCA in 1935. This example consisted of 6 stacked turnstile "bays" on a 70 foot mast. Each "bay" consists of two crossed 3.6 meter dipole driven elements, fed in quadrature (with a 90° phase difference). It radiated horizontally polarized radio waves with an
omnidirectional pattern. The purpose of the multiple bays is to increase the gain in horizontal directions and reduce the power radiated into the sky or down toward the earth. The source says it gave good reception for a radius of 25 to 30 miles. The turnstile antenna was used as a VHF transmitting antenna in some of the first FM stations during the 40s, but its horizontal polarization had the disadvantage that the signal strength in a receiver varied depending on the orientation of the antenna. FM stations now broadcast in circular polarization.
Caption:
Photos above and to the right show the new "turnstile" antenna array in use at short-wave station W8XH in Buffalo, N. Y. A 70 foot pole supports the antenna array.