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Showing results for tags 's-parameters'.
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Hi, I have a 4by4 symmetrical phased array, but something strange is happening with my S-parameters. Because my array is symmetrical, the following should approximately be the same: S11=S1616, S21 = S1516 etc. However, when I look in my .s16p file, S1516 is -180 degrees shifted in phase with respect to S21. What causes this shift? Thanks in advance! MWA_tile_sur_v3.cfx MWA_tile_sur_v3.cfx.bak MWA_tile_sur_v3.fek MWA_tile_sur_v3.opt MWA_tile_sur_v3.out MWA_tile_sur_v3.pfg MWA_tile_sur_v3.pre MWA_tile_sur_v3.str MWA_tile_sur_v3_SParameter1.s16p MWA_tile_sur_v3.bof MWA_tile_sur_v3.cfm MWA_tile_sur_v3.cfs
I’m trying to model a two-element dipole array that can be steered in azimuth arbitrarily, and I want to compute realized gain. To do that, I run two FEKO simulations, one with in-phase excitations, [V1 V2] = [1 1], and one with 180-degree out-of-phase excitations, [V1 V2] = [1 -1]. From FEKO I export far fields and S-parameters, then process in Matlab. I’m assuming that the S-parameters that Feko calculates are active S-parameters since Feko computes only one value for each port. Is this a correct assumption? Assuming it is, I calculate the passive S-parameters from the four active S parameters (S1 and S2 for both [1 1] and [1 -1] excitations). I then use these to calculate active S-parameters for arbitrary element phase, and use the calculated active S-parameters to calculate the reflection loss needed to compute the realized gain for the array. Unfortunately, my calculated results don’t agree with those from Feko. That is, if I steer the beam 45 degrees in Feko and in my Matlab code, the active S-parameters don’t agree. Have I made an incorrect assumption about how Feko operates or is there a flaw in my logic?