Low-Profile In-Band Pattern Diversity Antenna with Improved Bandwidth

In this paper, a low-profile, pattern diversity antenna with improved bandwidth and isolation is proposed for wireless and Internet-of-Thing (IoT) applications. The antenna is composed of a pair of shorted patches with four stubs, a hybrid ring coupler, and a pair of hairpin resonators. The coupler is to provide the shorted patch pair with in-phase and out-of-phase excitations, generating the unidirectional radiation and omni-directional radiations, respectively. In order to enhance the bandwidths, two hairpin resonators are integrated and coupled with the shorted patches through coupling slots, generating 2 ^nd -order filtering responses. As a result, the impedance bandwidths of the two operating modes are significantly improved without increasing antenna's thickness. The antenna is prototyped with the concept verified, exhibiting a good impedance bandwidth (4.9-5.1 GHz) when the antenna is working at different modes (uni-directional or omni-directional). The isolation between the two ports is about 30 dB. The proposed antenna can be a good candidate to improve the coverage of future intelligent wireless systems.