Analysis of Broadband Proximity Fed Gap-coupled C-shaped Microstrip Antennas.

The compact C-shaped microstrip antenna derived from rectangular microstrip antenna has been mainly analyzed at its fundamental mode. In this paper, fundamental and higher order modes of proximity fed C-shaped microstrip antennas are discussed. The broadband proximity fed C-shaped microstrip antenna is proposed. At its fundamental mode, it yields bandwidth of more than 230 MHz (> 23%) with broadside radiation pattern and peak gain of more than 7 dBi. Further increase in its bandwidth is realized by cutting rectangular slot on the edges of the patch. The slot reduces TM₀₁ mode frequency of C-shaped patch and along with its TM₁₀ mode, yields bandwidth of more than 260 MHz (> 28%). To increase the gain, gap-coupled configuration of two C-shaped microstrip antennas is proposed. This gives bandwidth of more than 300 MHz with peak gain of 7.7 dBi. Further to enhance the bandwidth, gap-coupled configuration of two rectangular slot cut C-shaped microstrip antennas is proposed. The slot reduces TM₀₁ mode frequency on each of the C-shaped patches and along with TM₁₀ modes, yields bandwidth of more than 400 MHz (~40%) with broadside radiation pattern and peak gain of more than 8 dBi. [ABSTRACT FROM AUTHOR]