A wideband capacitively fed circular‐E patch antenna

A wideband circular-E patch antenna with an air substrate and a capacitive feed is proposed. The circular-E patch is formed by inserting a pair of wide slits at the boundary of a circular patch, and the capacitive feed has a small metallic disk placed below the circular-E patch, supported by a conducting post, which is then connected to a 50 Ω SMA connector through a via hole in the ground plane of the patch antenna. A prototype of the proposed antenna is constructed, and experimental results reveal that a group of three adjacent resonant modes can be excited, which results in a wide 10 dB return-loss impedance bandwidth of about 35%. Acceptable radiation characteristics for operating frequencies across the obtained wide impedance bandwidth are also observed, and the gain variation within the bandwidth is seen to be less than 1.4 dBi, with a peak antenna gain of about 7.9 dBi. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 27: 134–135, 2000.