Linearly tapered slot antenna arrays for multibeam systems

A linearly tapered slot antenna (LTSA) acting as a single element and as an array element has been experimentally investigated. Although the antenna, used either for a single element or for 5 x 5 multibeam array elements, had the gain loss which was estimated as about one quarter of the total radiated power, due to cross-polarized radiation, the antenna yielded wide bandwidth, high gain, and high aperture efficiency. A new method to calculate the directivity and efficiency was developed, which is based on integration of co- and cross-polarized patterns in three planes. The directivity and efficiency was over-estimated when evaluated from co-polarized radiation patterns in the E/H-planes. The estimated aperture efficiency of an LTSA array used with a paraboloid, was 40-50% for an element spacing which resulted in cross-over levels of the beams about -3dB. This efficiency compares favorably with 60% for an optimum (cos)$\sp{q}$ feed pattern, at the same spacing. An equally spaced phased array with a slotline power combiner as a feed network was investigated, and the results agreed well with theoretical calculations