how to determines bandwidth of Microwave components

Hi,

Is there anyway to do manual analysis of, say a quadrature hybrid to determine its bandwidth (as I was able to do in low frequency cmos circuits)?
While discussing quadrature hybrid, Pozar writes " ... the bandwidth of a branch-line hybrid can be increased to a decade or more by using mutiple sections in cascade". Any analytical way to show if this statement is correct?
I have also noticed that (similar to what happens in a constant GBP opamp) if I increase the bandwidth, the value of S11 gets affected. Why this
happens ?

Hi,

Bandwidth in RF components is defined with respect to its S11 or returnloss.. Theoretically -10dB is taken for a mark but the lower or more negative the better. Industries take atleast 16 dB as reference and the band that falls below this in returnloss is taken to be bandwidth of the component..!

Regards

SpaceDust, Thank you for your response but I was perhaps not clear. What I wanted to ask was (I am being a little more specific):

(1) Can we do manual analysis to find theoretical bandwidth of Quadrature hybrid? If yes, how?
(2) Do we have S11×Bandwidth=constant kind of relation in Quadrature hybrid?

(I am new to RF/Microwave, coming from low frequency analog)

I haven't come across anything such of ur point 2,

But as of point one, u can do an even and odd mode analysis to derive some equations and plot them in matlab. U can find this procedure in the Pozar's Book..!

Regards..