what is a microstrip

plz tell me what is microstrip configuration.and what is a 3 port device in microstrip confiiguratiopn? i need 2 know it.

A microstrip is a PCB trace over a reference plane. The trace and the plane are separated by a dielectric.

There is a model of a 3 port microstrip power splitter at: http://www.cst.com/Content/Applications/Article/261

can u plz tel me what is circulator in microstrip confugiration

A circulator has 3-ports such that the signal entering each port can pass to the port adjacent to it (either clockwise or counter-clockwise) but not to the port in the other direction. It can be done with waveguides, wires, or microstrips by controlling the length and impedance of the connecting lines.

Is there some reason you are asking these questions on the forum instead of looking them up for yourself on the web? They are pretty simple RF definitions that can be found in many places.

The 3-port devices using microstrip structure also can be called: Power divider, Power spliter..
From what I'm thinking, you should better get some background knowledge for this kind of transmission line and its corresponding applications.
A good book, I think, that is "Microwave Engineering" written by David. M. Pozar.
After reading it carefully, you'll have what you're expecting.
regards!