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A Microstrip Half-Wave Filter. Cg. -q. -q. Y c. Y c. Admittance inverter used in the Microstrip half-wave filter. 1. 2. Y 1. Y 2. Y 3. (c). Equivalent circuit. Microstrip Parallel Coupled Filter. 1. a. 2. b. - I 2. I 1. - V. I 1. I 2. V. V. V. (a). (b). Even Mode.
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Cg -q -q Yc Yc Admittance inverter used in the Microstrip half-wave filter
1 2 Y1 Y2 Y3 (c) Equivalent circuit Microstrip Parallel Coupled Filter 1 a 2 b -I2 I1 -V I1 I2 V V V (a) (b) Even Mode Odd mode q
Yec, Yoc Yeb Yeb (Yoc-Yec)/2 (Yoa-Yea)/2 (Yob-Yeb)/2 Yea Yea Yec Yec Parallel Coupled Filter S.C Yc 1 2 Yea, Yoa 3 Yc Yeb, Yob
(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 Zoc+ Zod Zob+ Zoc 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 C1 C3 R=1 Low-pass prototype circuit