Decoupling Network Integrated With CSRR-Based Filtering Power Dividers for Antenna Arrays

This brief provides a mutual coupling suppression network for antenna arrays with high frequency selectivity. The proposed network is composed of three-order (denoting three decoupling bridges established by transmission lines) decoupling networks and unequal power dividers consisting of complementary split-ring resonators featuring bandpass and harmonic suppression responses. All the decoupling structures are highly integrated. A design example of a
$2\times 4$
patch antenna array, working at 4.9 GHz and integrated with the proposed decoupling network, is constructed and fabricated. Simulated and measured results indicate that the antenna array is well-decoupled involving the suppression of vertical, horizontal, and diagonal coupling paths. The measured common bandwidth of impedance matching (
$|S_{ii}~|$
<–10 dB) and isolation (> 25 dB) is from 4.8 to 5.1 GHz. A small insertion loss of 0.35 dB is introduced. Moreover, a filtering response is observed, and gain nulls are generated at the two sides of the operating band. As for the demonstrator, spurious up to 11 GHz is well suppressed and the peak gain at the harmonic band is reduced by over 20 dB, exhibiting a good harmonic suppression performance.