{"id":163821,"date":"2021-11-09T07:50:17","date_gmt":"2021-11-09T07:50:17","guid":{"rendered":"\/forum\/forums\/topic\/why-does-s21-show-big-difference-in-different-simulating-methods-verify-using-friis-equation\/"},"modified":"2021-11-12T04:41:52","modified_gmt":"2021-11-12T04:41:52","slug":"why-does-s21-show-big-difference-in-different-simulating-methods-verify-using-friis-equation","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/why-does-s21-show-big-difference-in-different-simulating-methods-verify-using-friis-equation\/","title":{"rendered":"Why does S21 show big difference in different simulating methods? & Verify using Friis equation"},"content":{"rendered":"
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Hi, I am trying to check interference between antennas using various simulation methods.<\/strong><\/p>\n

In terms of various simulation methods, specifically, one is<\/strong> that both of two antennas are surrounded by PML<\/strong> at once and the other is<\/strong> that each antenna is surrounded by separate FE-BI<\/strong>. TX Port Impedance<\/strong> is antenna input impedance and only RX Port Impedance<\/strong> is conjugate matching<\/strong> to input impedance. In detail, I attached picture and project file.<\/strong><\/p>\n

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But, S21 Result of each simulation shows big difference as I already mentioned in title. So, I use Friis Equation to verify which simulation is incorrect. (Beside boundary condition, other terms of setup are same)<\/strong><\/p>\n

Consequentially<\/strong>, S21 of PML simulation is identical to S21 of Friis Equation, but S21 of FE-BI is not.<\/strong><\/p>\n

I think that there is no error in terms of simulation setup. But, FE-BI doesn't satisfy Friis-Equation.<\/p>\n

So, anyone who know and explain how this situation happens or think that above simulation setup has something wrong?<\/p>\n

Any opinion about this trouble would be greatly appreciated in advance.<\/p>\n

<Simulation Setup><\/p>\n