Dual Band Coplanar Capacitive Coupled Microstrip Antennas with and Without Air Gap for Wireless Applications

This article presents the coplanar capacitive coupled probe fed microstrip antennas for dual frequency band operation. The proposed antenna is excited by a single probe feed connected to a capacitive strip. Of the two dual band antennas presented here, the first one uses small air gap and the other is designed without air gap. In the first case an effort has been made to reduce the height of suspended antenna. A vertical slot is placed to obtain antenna resonance at low frequency side, and also for proper impedance matching. After presenting the basic geometry the second configuration (which uses no air gap) which also offers dual band operation at the expense of reduced bandwidth is presented. Measured values fairly agree with the simulated results.