Effective techniques for extending the directivity-bandwidth of resonant cavity antennas

We present extremely simple techniques developed recently to address the bandwidth enhancement of resonant cavity antennas (RCAs) made out of unprinted dielectric slabs. These techniques are suitable for both unit-cell superstrate models as well as the finite-size RCA model in which superstructure area is optimized to increase the 3dB directivity bandwidth of RCA. It is shown that controlled dielectric and thickness contrast can be used as a defect to create wideband RCA superstrates in unit-cell design whereas the use of small superstrate area can directly enhance the 3dB bandwidth. Prototype antenna design is presented and results are included to demonstrate the improvements obtained. Significant improvements in 3dB bandwidth (≥50%) have been observed as compared to conventional designs while conserving design simplicity, practicality and ease of fabrication, which are the key advantages of presented techniques.