Microstrip antenna has many advantages of low profile, light weight, conformability, and manufacturing skill by photolithographic technique. With these advantages, microstrip antenna has been the important topic of antenna research, especially for array antenna. But microstrip phased array antenna has critical weakness of scan-blindness due to surface wave. To overcome this problem, cavity-backed microstrip structure was proposed, but its analysis and design procedure is not easy with commercial simulators.
We implemented the algorithm for analyzing cavity-backed circular microstrip antenna fed by probe. In order to validate the developed code, we have compared the experimental results and predicted one. There was good agreement with each other. And then, we extended this code for analyzing the array structure and the effect of radome, or superstrate. In each case, verification by experiment was performed.
For cavity-backed microstrip array, rectangular and triangular grid case was compared. We showed that array with triangular grid had better characteristics for phased array of conical beam scanning.
Microstrip antenna would be used with radome because it provides the advantages of protecting antenna from environmental hazard, enhancing the antenna gain and etc. Typically microstrip antenna has gain of 5-6dBi, beamwidth of 70-90˚ which is relatively broad beam pattern. Some of antenna application requires a high gain and narrow beamwidth. Using superstrate, we can get the gain about 25dBi with microstrip antenna. So algorithm for analyzing microstrip antenna with superstrate should be established. We implemented the algorithm and verified it with experimental results.