1. MICROWAVE FILTERS DESIGN COURSE NOTES Dr. Kawthar Zaki

2. 2 INTRODUCTION DEFINITIONS & CLASIFICATIONS OF MICROWAVE FILTERS FREQUENCY RANGE : 200MHZ TO 90 GHZ LOW FREQUENCY TECHNIQUES & THEIR LIMTATIONS AT HIGHER FREQUENCIES OPTICAL TECHNIQUES & THEIR LIMITATIONS CLASIFICATION BY TYPE: (LP, HP, BP, BS) CLASIFICATION BY FRACTIONAL B.W. CLASIFICATION BY TRANSIMISSION MEDIUM

3. Dr. Kawthar Zaki 3 LOWER FREQUENCY TECHNIQUES LIMITATIONS LOW FREQUENCIES ARE DEFINED TO BE BELOW @ 200 MHZ LUMPED ELEMENT SIZES (R, L, C) BECOME COMPARABLE TO WAVELENGTH RADIATION FROM ELEMENTS CAUSES UNDESIRABLE EFFECTS INCREASED LOSSES WIRE CONNECTIONS BETWEEN ELEMENTS BECOME PART OF CIRCUIT (PARASETICS) SOURCES & MEASUREMENT TECHNIQUES ARE UNSUITABLE AT HIGHER FREQUENCY

4. Dr. Kawthar Zaki 4 CLASIFICATION OF FILTERS BY PASS BAND TYPES Attenuation Freq. Attenuation Freq. Attenuation Freq. Attenuation Freq. L. P. FH. P. F. B. P. F. B. S. F. 0 0 0 0 fc fo b.w.

5. Dr. Kawthar Zaki 5 CLASIFICATION OF FILTERS (ctd.) BY FREQUENCY BANDS: BAND DESIGNATION FREQ. RANGE GHZ. P0.225 - 0.39 LOWER L0.39 - 1.55R.F. BAND S1.55 - 3.90 C3.90 - 6.20 MICROWAVE X6.20 - 10.9BANDS K10.9 - 36.0 Q36.0 - 46.0MILLIMETER V46.0 - 56.0WAVE W56.0 - 100.0BANDS

6. Dr. Kawthar Zaki 6 CLASIFICATIONS BY RESPONSE TYPE (INSERTION LOSS FUNCTION) BUTTERWORTH OR MAXIMALY FLATE T(  n TCHEBYCHEFF OR EQUAL RIPPLE PASS BAND: T(  2 T n (  INVERSE TCHBYCHEFF MAXIMALLY FLATE PASS BAND & EQUAL RIPPLE STOP BAND T(  2 T n (  ELLIPTIC FUNCTION OR QUASIELLIPTIC FUNCTION (EQUAL RIPPLE IN BOTH PASS BAND AND STOP BAND) BESSEL THOMPSON (FLATE GROUP DELAY)

7. Dr. Kawthar Zaki 7 CLASSIFICATION BY FRACTIONAL BAND WIDTH NARROW BAND FILTERS : RELATIVE (bw/fo) BANDWIDTHS LESS THAN @ 5% MODERATE BAND WIDTH : RELATIVE BANDWIDTHS BETWEEN @ 5% TO 25% WIDE BAND FILTERS : RELATIVE BANDWIDTHS GREATER THAN 25% TECHNIQUES USED FOR DESIGN OF EACH TYPE DIFFER SIGNIFICANTLY

8. Dr. Kawthar Zaki 8 CLASSIFICATION BY TRANSMISSION MEDIUM LUMPED & QUASI LUMPED ELEMENTS COAXIAL TRANSMISSION LINES MICROSTRIP LINES SUSPENDED SUBSTRATE LINES STRIP LINES RECTANGULAR OR CYLENDRICAL WAVEGUIDES HIGH DIELECTRIC CONSATANT FILLED (OR PARTIALLY LOADED) COAXIAL LINES OR WAVEGUIDES

9. Dr. Kawthar Zaki 9 FILTERS TRANSMISSION MEDIA FREQUENCY BAND DESIGNATION PLSCXKQV W RELATIVE B.W. %.01.1 1.0 10. 100LUMPED LC COAXIAL DIELECTRIC RESONATORS WAVEGUIDES PRINTED CIRCUITS AND SUSPENDED SUBSTRATES

10. Dr. Kawthar Zaki 10 A:Coaxial Resonators, Ceramic Dielectric B:Coaxial Resonators, Air Dielectric C: Single Mode Cavity Resonators D: Single Mode Cavity Resonators, Delectrically Loaded E: HTS Planar Resonators UNLOADED Q’S FOR BASE STATION FILTERS 100K 10K 1K QuQu Cost Size A B C D E (Technology Drivers) (Multiple Modes) Technology Gap Dual Mode, materials, etc.) (Materials Plating) Increased Circuit Complexity

11. Dr. Kawthar Zaki 11 IMPORTANCE OF MICROWAVE FILTERS FREQUENCY SPECTRUM ALLOCATION AND PRESERVATION INTERFERENCE REDUCTION OR ELIMINATION - RECEIVERS PROTECTION ELIMINATION OF UNWANTED HARMONICS & INTERMOD. PRODUCTS GENERATED FROM NONLINEAR DEVICES (MULTIPLIERS, MIXERS, POWER AMPLIFIERS) SIGNAL PROCESSING & SPECTRUM SHAPING FREQUENCY MULTIPLEXING

12. Dr. Kawthar Zaki 12 APPLICATIONS OF MICROWAVE FILTERS COMMUNICATION SYSTEMS: –TERRESTRIAL MICROWAVE LINKS: RECEIVERS PROTECTION FILTERS, TRANSMITTER FILTERS, CHANNEL DROPPING FILTERS, TRANSMITTER HARMONIC FILTERS, LOCAL OSCILLATOR FILTERS, MIXERS IMAGE REJECT FILTERS –SATELLITE SYSTEMS: » SPACE CRAFT: FRONT END RECEIVE FILTERS, INPUT MULTIPLEXERS CHANNELIZATION FILTERS, OUTPUT MULTIPLEXERS FILTERS, TRANSMITTERS HARMONIC REJECTION FILTERS »EARTH STATIONS : LNA’S TRANSMIT REJECT FILTERS, HPA’S HARMONIC REJECT FILTERS, UP & DOWN CONVERTERS FILTERS

13. Dr. Kawthar Zaki 13 APPLICATIONS (ctd.) MOBILE AND CELLULAR SYSTEMS : –BASE STATIONS RECEIVE PROTECTION –BASE STATIONS TRANSMITTERS FILTERS –SUBSCRIBERS HAND SETS DIPLEXERS –SATELLITE MOBILE APPLICATIONS »AERONAUTICAL TX/RX SYSTEMS »MARITIME SATELLITE TERMINALS »LAND MOBILE SATELLITE TERMINALS RADAR SYSTEMS HIGH POWER APPLICATIONS

14. Dr. Kawthar Zaki 14 TYPICAL COMMUNICATIONS REPEATER Antenna Tx Reject Filter LNA LO Up Converter Input Multiplexer Power Amplifiers Output Multiplexer

15. Dr. Kawthar Zaki 15 HOW TO SPECIFY FILTERS FREQUENCY SPECS: f 0 & BW (FOR B.P. OR B.S.), f c (FOR L.P. OR H.P.) PASS BAND INSERTION LOSS, RETURN LOSS AND FLATNESS (RIPPLE LEVEL) PASS BAND GROUP DELAY VARIATION SELECTIVITY OR SKIRT SHARPNESS OUT OF BAND REJECTION LEVELS SPURIOUS OUT OF BAND RESPONSE SPECIFICATIONS MASK

16. Dr. Kawthar Zaki 16 HOW TO SPECIFY FILTERS(ctd.) POWER HANDLING CAPABLITY –MULTIPACTOR EFFECTS & VOLTAGE BREAKDOWN ENVIRONMENTAL SPECIFICATIONS –OPERATIONAL TEMPERATUE LIMITS –PRESSURE & HUMIDITY ENVIRONMENTS –SHOCK & VIBRATION LEVELS MECHANICAL SPECIFICATIONS –SIZE, SHAPE & WEIGHT –TYPE OF INPUT/OUTPUT CONNECTORS –MECHANICAL MOUNTING INTERFACES

17. Dr. Kawthar Zaki 17 TYPICAL INSERTION LOSS SPECIFICATION MASK FREQUENCYf 0 (4000 MHz) INSERTION LOSS 0.6dB BW 36 MHz  =  dB 40 dB 50dB 60 dB 70 dB

18. Dr. Kawthar Zaki 18 TYPICAL GROUP DELAY SPECIFICATION MASK FREQUENCYf 0 (4000 MHz) GROUP DELAY

19. Dr. Kawthar Zaki 19 METHODS OF FILTER DESIGN 1. IMAGE PARAMETER METHOD (EARLY 1920’S) BASED ON A WAVE VIEWPOINT OF CIRCUITS 12 Z I2 21 Z I1 1122 Z I2 Etc. to Infinity Etc. to Infinity IMAGE IMPEDANCES Z I1, Z I2 AND IMAGE PROPAGATION FUNCTION  ARE DEFINED BY: Z I2 E2E2 I2I2 E1E1 Z I1 I1I1 + - + - EgEg e  = (E 1 /E 2 ) (Z I2 / Z I1 ) 1/2

20. Dr. Kawthar Zaki 20 CONSTANT K-HALF SECTIONS L 1 = 1 C 2 = 1 Z I2 Z I1       Z I1,Z I2   R I2 R I1 j X I1 j X I2 

21. Dr. Kawthar Zaki 21 M-DERIVED HALF SECTIONS  Z I1,Z I2   R I2 R I1 j X I1 j X I2           L 1 = m C 2 = m Z I2 Z I1 L=(1-m 2 )/m   =1/(1-m 2 ) 1/2

22. Dr. Kawthar Zaki 22 IMAGE PARAMETER FILTERS DESIGN PIECE TOGETHER ‘ENOUGH’ CONSTANT-K & M-DERIVED SECTIONS TO MEET REQUIRED ATTENUATION TERMINATION WILL BE DIFFERENT FROM THE IMAGE IMPEDANCE END SECTIONS ARE DESIGNED TO IMPROVE MATCH

23. Dr. Kawthar Zaki 23 2. INSERTION LOSS THEORY SYNTHESIS (DARLINGTON, 1939) SPECIFY TRANSFER FUNCTION OF COMPLEX FREQ. SATISFYING REALIZABILITY CONDITIONS FIND INPUT IMPEDANCE OR REFLECTION COEFFICIENT FROM TRANSFER FUNCTION DECOMPOSE TRANSFER FUNCTION & REFL. COEEF. TO TWO CASCADED PARTS: –A PART CORRESPONDING TO A SIMPLE SECTION OF KNOWN PARAMETRS –A PART OF LOWER ORDER THAN THE ORIGINAL TRANSFER FUNCTION ALSO SATISFYING REALIZABILITY CONDITIONS REPEAT SYNTHESIS CYCLE UNTILL REMAINING SECTION IS OF ZERO ORDER (CONSTANT TERMINATION) COMMON METHODS ARE CASCADE SYNTHESIS, PARTIAL AND CONTINUOUS FRACTION EXPANSIONS.

24. Dr. Kawthar Zaki 24 EXAMPLE OF CASCADE SYNTHESIS CYCLE FILTER TO BE SYNTHESIZED (UNKNOWN) T(s) = P(s)/Q(s) T(j  ) < 1 ; - <  Q(s) Strictly Hurwitz 88 REMAINING UNKNOWN SECTION T 1 (s) = P 1 (s)/Q 1 (s) 2 Extracted Section of Known Elements and Values T 1 (j  ) < 1 ; - <  Q 1 (s) Strictly Hurwitz 88 2

25. Dr. Kawthar Zaki 25 3. COMPUTER-AIDED DESIGN AND OPTIMIZATION START BY SPECIFICATIONS OF DESIRED RESPONSE OVER A BAND OF FREQUENCIES AND A GIVEN NETWORK OF ELEMENTS OF KNOWN (ASSUMED) STARTING VALUES ANALYZE THE NETWORK TO FIND IT’S RESPONSE OVER THE SPECIFIED FREQUENCY BAND COMPARE THE CALCULATED RESPONSE TO THE DESIRED RESPONSE BY FORMING AN ERROR FUNCTION CHANGE THE ELEMENT VALUES OF THE NETWORK (WITHIN CERTAIN BOUNDS) ACCORDING TO CERTAIN PRESCRIBED RULES TO MINIMIZE THE ERROR FUNCTION ITERATE THE PROCESS UNTILL THE ERROR FUNCTION IS REDUCED TO ZERO, DOES NOT DECREASE IN SUCCESSIVE ITERATIONS OR A PRESPECIFIED NUMBER OF ITERATIONS IS EXCEEDED

26. Dr. Kawthar Zaki 26 FILTER REALIZATIONS LOW PASS AND HIGH PASS SEMI-LUMPED ELEMENTS –COAXIAL –MICROSTRIP & STRIPLINE BAND PASS NARROW AND MODERATE BANDWIDTHS –COAXIAL “DUMBELL” –MICROSTRIP PARALLEL COUPLED AND END COUPLED –SUSPENDED SUBSTRATE –INTERDIGITAL, COMBLINE (COAXIAL) –WAVEGUIDES: RECTANGULAR, CIRCULAR SINGLE & DUAL MODE AND RIDGE WAVEGUIDE –DIELECTRIC OR METALLIC LOADED RESONATORS BAND STOP FILTERS

27. Dr. Kawthar Zaki 27 LOW PASS COAXIAL FILTERS COAXIAL CONNECTOR HIGH IMPEDANCE LINES (SERIES L’S) LOW IMPEDANCE LINES (SHUNT C’S) SEMI-LUMPED ELEMENTS EQUIVALENT CIRCUIT DIELECTRIC SLEEVE

28. Dr. Kawthar Zaki 28 HIGH PASS COAXIAL FILTERS SHUNT L SERIES C COAXIAL CONNECTOR SEMI-LUMPED ELEMENTS EQUIVALENT CIRCUIT

29. Dr. Kawthar Zaki 29 MICROSTRIP LOW PASS FILTERS METALIZED CIRCUIT PATTERN DIELECTRIC SUBSTRATE OVER GROUND PLANE

30. Dr. Kawthar Zaki 30 BAND PASS COAXIAL FILTERS DIELECTRIC SLEEVE  RESONATORS SERIES CAPACITORS ‘DUMBELL’ BANDPASS COAXIAL FILTER

31. Dr. Kawthar Zaki 31 PARALLEL COUPLED LINES  DIELECTRIC SHEET OUTER CONDUCTOR & HOUSING CENTER CONDUCTOR PATTERN SUSPENDED SUBSTRATE LINE MICROSTRIP PRINTED CIRCUIT REALIZATION RECTANGULAR COUPLED BARS FOR WIDER BANDWIDTHE & HIGHER Q’S POSSIBLE SUSPENDED SUBSTRATE REALIZATION (HIGHER Q) OVERLAY COUPLED LINES

32. Dr. Kawthar Zaki 32 BANDPASS END COUPLED MICROSTRIP FILTERS METALIZED CIRCUIT PATTERN  RESONATORS DIELECTRIC SUBSTRATE OVER GROUND PLANE

33. Dr. Kawthar Zaki 33 INTERDIGITAL & COMBLINE BAND PASS FILTERS INNER CONDUCTORS OF COAXIAL RESONATORS SHORT CIRCUIT END COUPLING IRIS TOP VIEWSIDE VIEW OPEN CIRCUIT END

34. Dr. Kawthar Zaki 34 WAVEGUIDE FILTERS INDUCTIVE WINDOWS (MODERATE BANDWIDTHS) DIRECT COUPLED USING IRIS (NARROW BANDWIDTHS)

35. Dr. Kawthar Zaki 35 RIDGE WAVEGUIDE FILTERS

36. Dr. Kawthar Zaki 36 DUAL MODE CIRCULAR WAVEGUIDE FILTERS 1 2 3 45 6 INPUT IRIS OUTPUT IRIS TUNING SCREWS

37. Dr. Kawthar Zaki 37 Dual Mode Dielectric or Conductor Loaded Resonator Filter 1 2 3 45 6 Dielectric or Conductor Loading Input Coax Probe Output Coax Probe

38. Dr. Kawthar Zaki 38 Dual Mode Dielectric or Conductor Loaded Resonator Filter in Rectangular Enclosure 8-Pole Dual Mode Longitudinal Dielectric or Conductor Loaded Resonator Filter in Rectangular Enclosure M 12 M 23 M 14 M 34 M 45 M 56 M 36 M 78 M 67 M 58