A Microstrip Half-Wave Filter

Cg -q Yc Admittance inverter used in the Microstrip half-wave filter

Microstrip Parallel Coupled Filter 1 a b 2 -I2 I1 I1 -V I2 V V V (a) (b) Even Mode Odd mode q Equivalent circuit Y1 Y2 Y3 1 2 (c)

Parallel Coupled Filter S.C Yc 1 Yea, Yoa 2 3 Yc Yeb, Yob Yec, Yoc Yea Yec (Yoa-Yea)/2 (Yoc-Yec)/2 (Yob-Yeb)/2 Yeb Parallel Coupled Filter

Reduced equivalent circuit for Parallel Coupled Filter (Yoc-Yec)/2 (Yoa-Yea)/2 (Yob-Yeb)/2 Yea Yea Yec Yec Reduced equivalent circuit for Parallel Coupled Filter

q a b c d Zoa+ Zob Zob+ Zoc Zoc+ Zod Zoa Zod (Zea- Zoa)/2 (Zeb- Zob)/2 (Zec- Zoc)/2 (Zed - Zod)/2 Z2 Z3 a q Z1 b q Parallel coupled filter using open-circuited coupled line sections And its equivalent circuit.

Example: Chebyshev bandpass filter Design a two-section Chebyshev Filter with 30% bandwidth, passband tolerance K2 =0.5, center freq.=6 GHz. Input/output impedance =50 Ohms. Z1 Z3 Z3 Z1 Zc Zc Z2 Z4 Z2 Two section parallel coupled line and its equivalent circuit

Design of a three section half wave bandpass filter Design a filter with f0 =10GHz, a bandwidth of 1 GHz, passband Tolerance k2 =0.1 , max VSWR=1.863

L2 R=1 C3 C1 R=1 Low-pass prototype circuit