Compact tunable network for closely spaced antennas with high isolation

A design technique of tunable decoupling networks for different closely spaced antennas is proposed. Different admittance parameters of the decoupling network could be obtained by tuning the input and output couplings, which can be used to minimize various mutual couplings between coupled antennas within a certain band of interest. To prove the concept, a decoupling network for Wi-Fi/Bluetooth antenna array is designed and fabricated. Measurement results have demonstrated that more than 20 dB isolation can be achieved within the operating frequency range in two different coupling cases.