number of sections in wilkinson power divider

hi everyone,

Im trying to design wilkinson power divider in ansoft designer, range 5-15 Ghz, input, output return losses, and isolation equal -30 db. Now im wondering how may sections in the transofmer i need to have to meet -30 db input return loss in the frequency range 5-15 Ghz?

thanks

You will likely need 3 sections, especially if the 30 dB requirement is mandatory. you can always trade isolation and return loss for bandwidth (and hence # of sections), but in your case, a 3:1 BW ratio will probably be 3 sections, minimum. I like to use the rule of that thumb that you need at least as many sections as octaves. So, if your BW ratio is 2:1, 2 sections, 3:1, 3, and so on. This rule, however, does not hold as well when you approach 10:1 type bandwidth. As the BW ratio increases, the less number of sections you need. For example, you can make very nice 10:1 wilkinson with only 7 sections, depending on isolation requirements.

A word of caution, at 15 GHz, you may find it VERY difficult to meet 30 dB return loss. When you go to layout the circuit and include line discontinuities and resistor parasitics, the 30 dB return loss will be challenging. The isolation is possible with some optimization, but the return loss, in my opinion, is a dream spec for you. Good luck!