Dual-mode patch antenna with PIN diode switch

Recently, since various wireless communication services such as the PDC, the PHS, and the wireless LAN are provided, it is required to make a mobile terminal to handle several wireless communication services. Generally, these services operate at different frequencies with different polarization and radiation characteristics. Therefore, it is necessary to design a multi-mode antenna which has multi-frequency band and different polarization and radiation pattern at each band, and the switching of the resonant modes should be controlled electronically. In this research, a dual-mode patch antenna is proposed where a PIN diode switch is used to change the resonant mode of the antenna. The characteristics of the antenna, such as the resonant frequency, radiation pattern, and the radiation efficiency are investigated experimentally and numerically.