Integrated filtering duplex patch antenna with small frequency ratio and high isolation

Abstract

An integrated filtering duplex antenna with small frequency ratio and high isolation is proposed in this article. First, a small transmitter‐receiver frequency ratio of stacked patch antenna is realized by soldering short circuit chips to the driven patch. Then, the asymmetric transmission zero technology is employed in the sets of dual‐mode resonators to realize high port‐to‐port isolation. Moreover, the ports coupling mode of the dual‐mode resonator is changed to achieve further Tx‐Rx isolation. For demonstration, the proposed antenna is fabricated and experimentally characterized in WCDMA band. The measured results show that it can mainly operate over the uplink and downlink operation band of WCDMA with an isolation level better than 32 dB, and the frequency interval (Δf = (f r − f t)) is only 0.09 times of the central frequency ((f r + f t)/2).