Isolation Improvement of Dual-Port Slot Antenna with Co-Polarized Pattern via Multi-Mode Concept

In this paper, an innovative approach is proposed for the co-polarized dual-port slot antenna with isolation improved. Firstly, the half-wavelength mode (model) and one-wavelength mode (mode2) of the slot antenna have been deeply investigated, and we have bent asymmetric distribution of the electric field successfully. As such, it could relocate the E-field cancellation point to the unexcited port of the slot antenna, while maintaining the maximum electric field at the excited port. Then, the resonant frequencies of modes1 and 2 are tuning by loading the short-ended bridges and shorted-ended branch. It makes the modes1 and 2 can be combined at 4.75 GHz. Based on this principle, we have combined three modes for the antenna for mutual coupling reduction. Finally, we machine and measure the antenna, which proves that the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S₁₂</tex> is better than 22dB and the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S₁₁</tex> is 21.5% from 4.57GHz to 5.68GHz, representing a great improvement. In addition, the bidirectional radiation patterns are successfully gained.