New elements that provide pattern versatility in coax and wavestar antennas

A pair of bent monopole elements attached to the mast and excited by a slot has been found to have very useful properties for cylindrical slot-array antennas employed in TV broadcasting. By inserting these elements, the inherent slot pattern can be controlled and a vertical component can be obtained for CP broadcasting. A variety of azimuthal horizontal and vertical polarization patterns have been achieved, showing great versatility, including more directional pattern of the cosφ-type for higher gain per element and less mutual coupling between adjacent slots. In the case of full CP, good axial ratio in the overall radiation pattern has also been accomplished. Negligible changes in the slot-array bandwidth were observed by introducing these elements