A shared aperture microstrip antenna for S/C-band communications

Systematic design approach for a shared aperture dual band microstrip antenna, its realization and successful demonstration have been described in this manuscript. This shared aperture microstrip antenna operates at S- and C-bands with higher feature and is linearly polarized (LP) in each of the bands. The S-band element is a two-layer electromagnetically coupled (EMCP) cross shaped patch. The cross shaped patch on the lower substrate is equitably fenced with 4 square patches for C-band operation. With the aid of an appropriate external microstrip comparator the C-band patches are excited for amplitude comparison monopulse tracking operation. The antenna demonstrates dual-axis monopulse tracking at C-band, which is its superiority over the earlier reported developments. At the C-band, it shows an impedance bandwidth >= 3.7% with a gain of 11.3 dBi. The monopulse tracking is successfully achieved over a bandwidth of approximate to 3.5%. It can track object unambiguously over +/- 23 degrees of the antenna boresight. The inclusion of tracking feature at C-band, with 3.5% tracking bandwidth with C-band elements in a single layer microstrip design and ability of error free tracking within +/- 23 degrees of the boresight are the novelty of the present development. The antenna reveals >= 1.9% impedance bandwidth at S-band with a gain of about 6.2 dBi.