Compact Co-polarized PIFAs for Full-Duplex Application Based on CM/DM Cancellation Theory

In this article, a compact co-polarized decoupled antenna for full-duplex application working at 1.71 GHz is proposed. The antenna is composed of two back-to-back air-dielectric planar inverted-F antennas (PIFAs) with zero edge-to-edge distance. The whole system is included in a compact volume of $0.45\lambda _{\mathrm {\mathbf {0}}} \times 0.45\lambda _{\mathbf {0}} \times 0.02\lambda _{\mathbf {0}}$ . The proposed antenna is designed based on the common mode (CM)/differential mode (DM) cancellation theory and its design guideline is illustrated in detail. Isolation maximum of 42 dB, broadside gain of 6.7 dB, and efficiency of 90% have been achieved in the proposed structure. There is a 1.9 dB gain difference between the broadside gain and the maximum gain. The proposed antenna shows its potentials in the radio frequency front-end incorporate design.

I. Introduction

With the development of modern communication system, higher requirements are raised for the radio frequency front-end (RFFE), such as integrated, militarized, and lightweight. Therefore, the incorporate design of RFFE between the antenna and the transceiver is becoming a new trend and has drawn the attention of many researchers. The incorporate design of RFFE can effectively reduce the volume and weight of the communication system. What is more, the spectrum efficiency of the system can be greatly enhanced. In fact, integrating the antenna with the duplexer is the key of the RFFE incorporate design, which is the so-called full-duplex antenna.