A Low-Profile Wideband Microstrip Antenna With Pattern Diversity Based on Composite Right/Left-Handed Transmission Lines

A low-profile wideband microstrip antenna is proposed based on the structure of composite right/left-handed transmission lines (CRLH TLs). The dimensions of the proposed antenna are 64 × 64 × 4 mm. The impedance matching bandwidth is 5.05-5.92 GHz (16.5%). The unit cell of the CRLH TLs is a mushroom structure. Several different resonant modes with different radiation patterns are excited to obtain the pattern diversity. Particularly, TM
₁₀
and TM
₂₀
modes are merged to realize a wideband performance with broadside radiation pattern, whereas the TM
₂₀
mode is used to realize a conical radiation pattern. The simulations and measurements are in good agreement, and the envelope correlation coefficient shows that the proposed antenna owns an excellent diversity performance.