Broadband Hybrid Decoupling Method for a Dual-Polarized Antenna With High Isolation

This letter presents a hybrid decoupling technique to realize high isolation for dual-polarized dipole antennas. The proposed antenna consists of a cross-dipole on two horizontal layers, one in the x-axis direction directly fed by a coaxial line and its extended strip and another in the y-axis direction differentially excited by a wideband power divider. A wideband hybrid decoupling method is applied, and the designed antenna has a simulated port-to-port isolation of more than 52.4 dB in the overlapped −10 dB impedance wideband of 1.69–2.73 GHz (47.1%). The fabricated prototype obtains a high port-to-port isolation of more than 48.3 dB over the 1.73–2.73 GHz (44.8%) frequency band. At the same time, the antenna has a stable radiation pattern, realized gains of 8.6 ± 0.7 dBi at Port 1 and 8.7 ± 0.6 dBi at Port 2, and an average radiation efficiency of 86.2%. The above characteristics indicate that the proposed antenna qualifies as a candidate for the base station antenna system in the 1.7–2.7 GHz frequency band.

I. Introduction

In Recent years, high-isolation wireless communication has received extensive attention and research. Frequently used decoupling technology is the key to realizing high isolation. Many decoupling techniques have been applied, such as using different polarization modes, slotting to perform filtering functions, multiport decoupling techniques, and short-circuit pin decoupling [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13]. Differential feed structure is a classical way to realize high isolation [1], [2], [3], [4] because it can maximize self-interfering signals to cancel each other out without introducing external factors. The short-circuit needle can effectively solve the problem of solid coupling current [10], [11], [12]. The dual polarization of the stimulated radiators perpendicular to each other can minimize the coupling current. However, the antennas that achieve high isolation communication in the above way are mostly patch antennas with relatively narrow bandwidths. Meanwhile, ultrawideband (UWB) antennas face the problem of pattern instability and significant fluctuations in radiation gain [13].