Help needed for designing a matching network

Hi everyone

I am designing a matching network for a monopole antenna working from 50 MHz to 250 MHz. I designed a low Q matching network for one particular frequency with a corresponding load impedance of the antenna.


The s11 was really good but the problem that I am facing now is the load impedance of the antenna changes for different operating frequency so the matching network is not really good for other frequencies.

I kindly request you to give some ideas to solve this problem.

Regards

Manu

Try o increase the number of poles of the matching network.

This is a complex problem (sorry for the pun). Theoretically you can get the impedance you want at N frequency points with a 2N element network.

In the ancient days this was trial and error on a smith chart.

Today it is automated. All microwave simulators have this capability with their optimizer. Eagleware Genesys has a design and optimization module and Nuhertz filter program has a design module.

You have several options. Have a professor consult for you and they will use one of these programs. The other is to get a trial license for one of them.

y can use the VNA get the impedance at first and then use the ADS to do the matched network

Try Multi-Section Low Q Matching

http://rfic.eecs.berkeley.edu/~nikne...f/bookchap.pdf


Don't forget push help button

thanks every one for the valuable response.

I am using ADS and I obtained the s11 of the antenna from VNA and specified it in ADS as 1 port s parameter file.

It is possible to solve this problem by using a Impedance matching utility in ADS by specifying a smart component in the circuit.

if yes please let me know how to do it as I am not familiar with this utility

Teteamigo thanks for the document i will use it to solve this problem.

Hi there,
With ADS you could also just run S11 optimization of your matching components at 3 frequencies (mid and extreme of bandwidth). I'm sure it would give you a satisfactory result in less than one minute :D
Just a quick remark: Is the S11 measurement performed in the exact plan of the antenna input? Although lambda at 50-250 MHz is large, don't forget to de-embed the S11 measurement that you imported in ADS...
Mosieur_Oiso

Two octaves of usable bandwidth out of a monopole is a good trick, You would be well advised to look into the radiation patterns fo your structure to make sure that it is producing useful patterns over the full band. Getting a good s11 is only the first step in the antenna design.