Hello,
Yes, FR4 is not good for your High Frequency filter.. Try alumina (Er 9.8)...
There are good books on Filter Design & also synthesis works with AWR Microwave Office...
Text book:
J.-S. G. Hong and M. J. Lancaster, Microstrip filters for
RF/microwave applications, John Wiley & Sons, Inc.,
2001.
• References:
G. Mattaei, L. Young, and E. M. T. Jones, Microwave
filters, impedance matching networks, and coupling
structures, Artech House, Norwood, MA, 1980.
• Filter Synthesis Software
Nuhertz Filter Solutions
**broken link removed**
It also interfaces to Sonnet Lite Free Electromagnetic Simulation software for your
distributed filter simulation...
http://www.sonnetsoftware.com/products/lite/index.html
---manju---