Port and Radiation Pattern Decoupling of Dielectric Resonator Antennas

A new decoupling method is proposed in this paper, which simultaneously realizes port and radiation pattern decoupling, namely high isolation and undistorted radiation patterns, respectively. The proposed decoupling method shows its effectiveness in 1 × 2 dielectric resonator (DR) antennas (DRAs) even with zero spacing. Conformal strips are attached on the side wall of the DRs and parallel to the E-plane of the DRAs. Coupled from the resonant DR, the conformal strips can generate induced current, thus forming induced field inside the DR. It can be noted that, inside the two DRs, the DR resonant field and strip induced field are anti-phase and in-phase, respectively. Tuning the conformal strips can change the amplitude ratio and phase difference between the resonant and induced fields, which can be used to cancel the fields inside the DR based on superposition principle. When one DR is excited, the field inside the other DR can be very weak. The DRs can then work at their fundamental TE_δ11 modes independently. Therefore, their radiation patterns are not distorted together with a high port isolation. A new indicator, energy storage proportion (ESP), is proposed to evaluate the decoupling effect. It can be found that when the ESP gets close to 1, the radiation patterns will be restored together with a high isolation. To verify the idea, 1 × 2 DRAs are designed, fabricated and measured. Reasonable agreement can be observed between the measured and simulated results for both H- and E-plane decoupled cases. All the measured overlapping impedance bandwidths are larger than 6%, the envelope correlation coefficients are lower than 0.059, and the isolations are higher than 20 dB. It should be highlighted that all the radiation patterns in this paper have been restored, useful for practical applications using multiple-input multiple-output techniques.