Microstrip antennas are used in various airborne applications in various configuration. In our paper, design of series-fed printed arrays for a Ku-band forward firing and backing firing beam is described. Each series-fed array has 13 elements and a beamwidth of 12 deg. The beams are tilted at an angle of 60 deg in axial plane of the cylindrical shell. The design of each type is done using a combination of moment method in spectral domain and transmission line theory. The two beams are overlapped by feeding the respective arrays at opposite ends. The designs are iterated after measurements on prototypes. Since a linear series-fed array doesn't give uniform coverage in the roll plane, each type is extended into a planar but wraparound configuration by using reactive power dividers of 5 stages. The total antenna consists of the two type of arrays that are co-mounted like inter-digital comb-lines and are fed with a SMA connector at feed end. Since beams are over-lapping in space, anyone of them can be used as transmit or receive antennas. The paper shows the design, theoretical results and measured results of input impedance and radiation patterns.
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