Two-Port Pattern Diversity Antenna for 3G and 4G MIMO Indoor Applications

A two-port pattern diversity antenna is presented. The antenna is a combination of a low-profile monocone antenna and a broadband microstrip antenna. The low-profile monocone antenna is loaded with a cup-shaped patch and shorted with four metallic wires to the ground. The broadband microstrip antenna is fed by a probe-ring-slot coupling structure. The two antennas are integrated by sharing parts of the antenna radiators, resulting in a compact structure. The difficulties of placing coaxial cables are simply solved by reusing the shorting wires. A prototype of the proposed antenna is designed, fabricated, and measured. Its overall height is 3.915 cm. The low-profile monocone antenna achieves an impedance bandwidth of 114% from 750 MHz to 2.73 GHz, covering the GSM-850/900, GSM1800/1900/UMTS, and LTE800/2300/2500 bands. The broadband microstrip antenna provides an impedance bandwidth of 44% from 1.89 to 2.9 GHz, covering UMTS/LTE2300/2500 bands. The isolation between the two antennas is greater than 15 dB in the whole bands. The low-profile monocone antenna has a monopole-type radiation pattern, and the broadband microstrip antenna has a microstrip-antenna-type radiation pattern, which indicates that the proposed antenna can provide pattern diversity characteristics. The proposed antenna is suitable for 3G and 4G indoor applications and is also compatible with 2G (GSM) applications.