Hi Mike,
Here is a 3 pole helical filter centered at 465 MHz. The filter is "C" coupled so the skirt on the high side rolls more gentle than low side. The insertion loss and return loss as well center freq are pretty spot on with expected. The DR on the second pix shows we can see down at least 65 dB and if I set the reference point to the screen top, perhaps 70 dB. Next, I'll try the big box. I expect very similar results although if I were to read the R+jX values at each and every frequency point there will be delta values. Alan
