Technique of Ground Size Tuning for Isolation Between Monopoles in Compact Wireless Terminals

Achieving good isolation between two antennas in a wireless terminal is a challenge, especially if it is small compared to the wavelength. This communication presents a technique useful for two monopoles. It is based on placing the monopoles collinearly and tuning the ground plane size to approximately λ/4. Simulations and measurements are presented to illustrate the technique. Different methods of tuning the ground plane size in small terminals are discussed.