Design a broad band DC bias network

Dear friends:

In order to design a broad band DC bias network, I designed a microstrip radial stub.
I have almost get about 2.5 GHz bandwidth.

A) Is this a typical bandwidth using radial stubs?

B) To reach higher bandwidths, what do you suggest?
Should I use an array of stubs? or should I use some elements?

Many thanks in advance.

Helical inductor, just sugggesting,

I finally read a good explanation of the helical (cone shaped) inductor, and why it is broadband. In a normal cylindrical coil, you have many turns of the same size. Each turn has an inductance and a wire-to-wire capacitance. All of those L-Cs resonate at the exact same frequency, and cause a problem. In a conical shaped inductor, each turn is slightly different in size, so its resonant frequency is going to be different from the turn right next to it. So you end up with 10 or so micro resonances, rather than one major resonance. The effect is a SRF of up to 40 GHz!

nice explanation Bbiff44 , would you please send a link for it , or tell us the reference

Khouly

Thank you very much friends,
biff44: Could you please give us a reference to see more about helical inductor?
Best

There are cormmercially available helical inductors for broadband bias tees.
I saw up to 8 uH and SRF 40 GHz