Design of Active Filter Using Substrate Integrated Waveguide

Abstract

In this project we have designed circuit models for Substrate Integrated Waveguide (SIW) filter at X band with a bandwidth of 1 GHz. These equivalent models are designed in ADS using lumped and semi-lumped approach. Based on these models a 3D structure of the filter is designed in CST. This design is fabricated on a Rogers 5880 substrate using photolithography and corresponding measurements are done to compare with simulations. In the second half of the project SIW filter is used with an active element to achieve non negative insertion loss. This can be achieved by using a negative resistance element such as Gunn Diode, Tunnel Diode etc. Gunn diode model is designed using JFETs which is integrated with the filter to demonstrate active filtering. Alternatively another method is explored using PHEMTS. PHEMT used in this case is VMMK 1225 from Avago Technologies.