A lowpass decoupling network for two coupled antennas

This paper presents a lowpass decoupling network (LDN) for a pair of strongly-coupled antennas working at the same frequency. Compared with the state-of-art decoupling techniques, the LDN has a simple circuit configuration. Moreover, it has less impact on the matching bandwidth. To demonstrate the concept, a fifth order LDN is designed and fabricated using LTCC technology to decouple a symmetric PIFA antenna pair working at 1.27 GHz. Measurement results show more than 14 dB isolation improvement is obtained with the matching bandwidth almost unaffected. Meanwhile, the radiation efficiency is increased by 15% near the working frequency.