Some questions on Ring Resonator Circuits..

Few questions here..

1) How do we determine the width of the square loop resonator if we set our resonant frequency at let's say 2.5 GHz ? Is there any formula to this? Or the width of the loop is actually self set?

2) for nλ = 2πr , n is the mode number, and so what does this mode number refers to? I know it is something to do with TMmnl where m is root number of each n and l is 0. How to determine what mode ?

Thanks

hi
u can find this formula in book s of plump element by bahl or ring microwave by K.cheng