Far-Field Decoupling of Two-Element Antenna Transceiving System by the Periodic Near-Field Resonators

In this letter, a hybrid wideband decoupling method based on far-field radiation regulation by employing the specially engineered periodic near-field resonators, which consist of split-ring resonator (SRR) arrays, is presented for the two collinear transceiving horn antennas with extremely large element spacing. Two E-plane-coupled antennas operating at X-band are arranged with center-to-center distance of 8 m (over 200λ). By allocating the SRR arrays in close proximity to each horn antenna, the radiation power in the specified horizontal directions pointing to each other could be significantly reduced without disturbing their radiation characteristics in the broadside thus leading to the conspicuous port isolation enhancement. It is validated that more than 25 dB mutual coupling level reduction is achieved over the frequency range of 8–11.5 GHz (∼35.9% fractional bandwidth) when the SRR arrays are integrated. Finally, a prototype was fabricated and measured. Corresponding measurement results are in good agreement with the simulated ones.