Radial microstrip slotline feed network for circular mobile communications array

A planar circular array with endfire linearly tapered slot antenna (LTSA) elements [Simons and Lee, 1992] is described. The LTSA has several advantages which include high element gain, wide bandwidth, equal beam width in the two orthogonal planes by proper choice of flare angle and simple construction. The circular array radiates in the radial direction in the azimuth plane and hence eliminates the need for phase shifters and mechanical scanning hardware. To achieve the elevation angle a ground plane is placed below the array which causes the beam to tilt above the horizon. The ground plane also simulates the metal roof top of vehicles. The feed network consists of a sixteen way radial power splitter which is electromagnetically coupled to the LTSA circular array. Electromagnetic coupling eliminates pin and solder connections and therefore improves reliability and lowers the cost. It also results in a wider bandwidth. This type of feed network is very simple and therefore has potential applications in several other configurations of planar microstrip patch arrays also.<>