Someone has asked me to tune a notch duplexer that needs tuning for frequencies around 460MHz. I don't know the design of this, as I don't have it yet, but it is likely to be a coupled resonator filter of some sort. I wonder if the TDR thing that Joel worked on for his Ph.D. can be used, if I do not have a mathematical model of the filter. I noted that Agilent used to sell some software for this, but I got the feeling that one needed a model of the filter to start with, which is fine if you have designed it from scratch, but not so useful if you have an unknown design.

Clearly a 3 (or more) port VNA is the ideal tool for this, but I only have a 2-port 8720D, but it does have the TDR option. I am wondering if that can be used to help do this.

Dave

Clearly a 3 (or more) port VNA is the ideal tool for this, but I only have a 2-port 8720D, but it does have the TDR option. I am wondering if that can be used to help do this.

Dave

> Sure, not model is needed if you are just tuning resonators (fixed coupling). app note 1287-8 shows the details.

Thank you Joel, I found application note 1287-8 at

http://cp.literature.agilent.com/litweb/pdf/5968-5328E.pdf

and will take a look. It is a bit easier to read than your Ph.D. thesis. Maths is not my strongest topic - hence I tended to steer my Ph.D. away from too much mathematical stuff.

Dave