A Self-Interference Suppression Structure for Collinear Dipoles

In this letter, a broadband self-interference (SI) suppression structure is presented for collinear dipoles. By using this structure, an average SI improvement of 21.6 dB is realized within the frequency band of 2.2–2.7 GHz. It has a 14.8% operating bandwidth of transmit-receive isolation higher than 50 dB. The working mechanism and bandwidth extension are discussed. Moreover, the key parameters and the influence of the proposed structure to the dipoles were also studied and presented. Measured results demonstrate that this design provides a wider operating bandwidth, omnidirectional radiation patterns, and ideal distribution distance. It is effective and suitable for reducing the SI between collinear dipoles.