IMPROVEMENT OF ISOLATION AND ENVELOP CORRELATION COEFFICIENT USING C-LOADED λ/4 LOOP ANTENNA ON HOLLOW GROUND

A C-loaded lambda/4 loop antenna on a hollow ground is presented to improve the isolation and envelop correlation coefficient ( ECC) in the mobile terminals. The designed antenna is composed of a straight type of C-loaded lambda/4 loop on hollow ground and a monopole branch operating for LTE800 and LTE1900 bands, respectively. The proper value of a loaded capacitor of the loop makes lambda/4 resonance, resulting in the parallel current flow on the ground plane while a conventional planar inverted-F antenna ( PIFA) generates a vertical current flow in the ground. Thus, the combination of two antennas will give rise to high isolation and low ECC. The isolation and ECC of both cases of PIFA ( primary) versus PIFA ( secondary) and PIFA ( primary) versus C-loaded lambda/4 loop antenna with a monopole branch ( secondary) are compared when they are diagonally placed in a mobile handset. The isolations in the former and latter cases are measured to be lower than 25.3 and 222 dB in the LTE800 band, respectively. Also, the ECC values in the former and latter cases are measured to be 0.81 and 0.29 from far-field radiation patterns in the LTE800 band, respectively. (C) 2016 Wiley Periodicals, Inc.