Low-Profile Broadband Antenna With Pattern Diversity

A pattern diversity antenna with low profile and wideband operation is proposed in this letter. The topology combines a 3-D folded monopole antenna together with a differential L-plate fed patch antenna. The monopole antenna is realized by a pair of bent hexagon-shaped plates, which can provide a conical pattern in the horizontal plane. A common top hat is capacitively loaded to reduce the overall height of the monopole antenna. This hat is excited as a microstrip antenna by differential feeding plates, which achieves a broadside radiation pattern. The operating band of the proposed antenna is in the range of 1.65-2.7 GHz (48%), covering the GSM1800/1900, UMTS, and LTE2300/2500 bands. By the method of differential feeding, the coupling between the two radiation modes can be greatly reduced, which can provide a low envelope correlation coefficient (≤30 dB) and a high isolation (>30 dB) between different ports. A prototype of the antenna with dimensions 60 × 60 × 20 mm3is fabricated, and the measured results are in great agreement with the simulated ones.