Design of 1.3 GHz Microstrip Highpass Filter Using Optimum Distributed Short Circuited Stubs

This paper presents an optimum distributed microstrip structure highpass filter having a cutoff frequency 1.3 GHz. The distributed elements used for this design are such as commensurate (equal electrical length) transmission line elements. The proposed design consists of shorted circuited stub microstrip transmission lines on a commercial substrate (RT/D 5880) with a relative dielectric constant 2.2 and 1.57 mm thickness. This filter exhibits a highpass band with steep cutoff. A sample filter is designed based upon the theory presented and it has been simulated with the S-parameters and IE3D software. Advanced computer aided design tools and a high precision thin film process make such filters predictable and repeatable. These filters have less radiation, dispersion and sensitivity to nearby objects.