Isolated Microstrip Line Combined With Characteristic Mode Analysis to Improve Isolation of Metasurface Antennas

In this letter, an isolated microstrip line (IML) combined with characteristic mode analysis (CMA) to further improve isolation is applied to design a high-isolation metasurface dual-polarized antenna with a low profile as an example. Based on CMA, the isolation of the antenna is effectively improved by about 16 dB after adding IMLs at the appropriate locations. The most important isolation enhancement mechanism is that the equal amplitude but reversed phase currents on IMLs are either directly canceled out or coupled with the surrounding currents and then canceled out. IML combined with CMA (IML-CMA) to improve isolation for different frequency bands is then discussed. IML-CMA is an approach that can be well applied to the isolation enhancement of metasurface antennas by performing CMA.