Transcript MICROWAVE FILTERS DESIGN COURSE NOTES PREPARED …

MICROWAVE FILTERS DESIGN
COURSE NOTES
Dr. Kawthar Zaki
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
Dr. Kawthar Zaki
2
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
Dr. Kawthar Zaki
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CLASIFICATION OF FILTERS
BY PASS BAND TYPES
Attenuation
Attenuation
L. P. F
H. P. F.
0
Attenuation
fc
0
Freq. Attenuation
b.w.
fc
Freq.
B. P. F.
B. S. F.
0
0
fo
Dr. Kawthar Zaki
Freq.
b. w.
fo
Freq.
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CLASIFICATION OF FILTERS
(ctd.)
• BY FREQUENCY BANDS:
BAND DESIGNATION
FREQ. RANGE GHZ.
P
0.225 - 0.39
LOWER
L
S
C
X
0.39 - 1.55
1.55 - 3.90
3.90 - 6.20
6.20 - 10.9
R.F. BAND
K
10.9 - 36.0
Q
36.0 - 46.0
MILLIMETER
V
46.0 - 56.0
WAVE
W
56.0 - 100.0
BANDS
Dr. Kawthar Zaki
MICROWAVE
BANDS
5
CLASIFICATIONS BY RESPONSE TYPE
(INSERTION LOSS FUNCTION)
• BUTTERWORTH OR MAXIMALY FLATE
T(w) = 1+ (w/wo) n
• TCHEBYCHEFF OR EQUAL RIPPLE PASS
BAND:
T(w) = 1+ e2 Tn(w/wo)
• INVERSE TCHBYCHEFF MAXIMALLY FLATE
PASS BAND & EQUAL RIPPLE STOP BAND
T(w) = 1+1/ e2 Tn(w/wo)
• ELLIPTIC FUNCTION OR QUASIELLIPTIC
FUNCTION (EQUAL RIPPLE IN BOTH PASS
BAND AND STOP BAND)
• BESSEL THOMPSON (FLATE GROUP DELAY)
Dr. Kawthar Zaki
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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
Dr. Kawthar Zaki
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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
Dr. Kawthar Zaki
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FILTERS TRANSMISSION MEDIA
PRINTED CIRCUITS
AND SUSPENDED SUBSTRATES
LUMPED
LC
RELATIVE B.W. %
100
10.
COAXIAL
DIELECTRIC
RESONATORS
1.0
WAVEGUIDES
.1
.01
P
Dr. Kawthar Zaki
L
S
C
X
K
FREQUENCY BAND DESIGNATION
Q
V
W
9
UNLOADED Q’S FOR BASE
STATION FILTERS
(Technology Drivers)
100K
10K
Qu
Dual Mode,
materials, etc.)
E
D
(Multiple Modes)
Technology Gap
(Materials
Increased Circuit
Plating)
Complexity
B
A
C
Cost
1K
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
Dr. Kawthar Zaki
Size
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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
Dr. Kawthar Zaki
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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
Dr. Kawthar Zaki
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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
Dr. Kawthar Zaki
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TYPICAL COMMUNICATIONS
REPEATER
Power
Amplifiers
Antenna
Tx Reject
Filter
LNA
LO
Up Converter
Input
Multiplexer
Output
Multiplexer
Dr. Kawthar Zaki
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HOW TO SPECIFY FILTERS
• FREQUENCY SPECS: f0 & BW (FOR B.P. OR
B.S.), fc (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
Dr. Kawthar Zaki
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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
Dr. Kawthar Zaki
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TYPICAL INSERTION LOSS SPECIFICATION
MASK
INSERTION LOSS
40 dB
e = .05 dB
0.6dB
BW
36 MHz
50dB
60 dB
70 dB
f0 (4000 MHz)
Dr. Kawthar Zaki
FREQUENCY
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TYPICAL GROUP DELAY SPECIFICATION MASK
GROUP DELAY
f0 (4000 MHz)
Dr. Kawthar Zaki
FREQUENCY
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METHODS OF FILTER DESIGN
1. IMAGE PARAMETER METHOD (EARLY 1920’S)
•BASED ON A WAVE VIEWPOINT OF CIRCUITS
1
2
2
1
ZI2 ZI2
1
ZI1 ZI1
Etc. to
Infinity
2
2
1
ZI2 ZI2
Etc. to
Infinity
• IMAGE IMPEDANCES ZI1, ZI2 AND IMAGE PROPAGATION FUNCTION
g ARE DEFINED BY:
ZI1
Eg
I1
+
E1
- Z
I1
Dr. Kawthar Zaki
ZI2
I2
+
E2
-
ZI2
eg = (E1/E2) (ZI2 / ZI1)1/2
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CONSTANT K-HALF SECTIONS
ZI1, ZI2
L1 = 1
RI2
ZI1
C2 = 1
ZI2
1
j XI1
RI1
a,b
w
1
a
j XI2
b
Dr. Kawthar Zaki
p/2
1
w
20
M-DERIVED HALF SECTIONS
ZI1, ZI2
L1 = m
RI2
L=(1-m2 )/m
ZI1
C2 = m
ZI2
j XI1
1
RI1
w
1
a
j XI2
b
w
8
1
w
w =1/(1-m2)1/2
8
p/2
Dr. Kawthar Zaki
w
8
a,b
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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
Dr. Kawthar Zaki
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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.
Dr. Kawthar Zaki
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EXAMPLE OF CASCADE SYNTHESIS CYCLE
2
(
)
T jw =
Output Power
Max . Avail . Power
2
T(s) = P(s)/Q(s)
8
<w<
Q(s) Strictly Hurwitz
T(jw) < 1 ; -
8
FILTER TO BE
SYNTHESIZED
(UNKNOWN)
REMAINING
UNKNOWN
SECTION
Dr. Kawthar Zaki
2
<w<
Q1(s) Strictly Hurwitz
T1(jw) < 1 ; -
8
T1(s) = P1(s)/Q1(s)
8
Extracted Section
of Known Elements
and Values
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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
Dr. Kawthar Zaki
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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
Dr. Kawthar Zaki
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LOW PASS COAXIAL FILTERS
DIELECTRIC
SLEEVE
HIGH IMPEDANCE LINES
COAXIAL CONNECTOR
(SERIES L’S)
LOW IMPEDANCE LINES
(SHUNT C’S)
SEMI-LUMPED ELEMENTS EQUIVALENT CIRCUIT
Dr. Kawthar Zaki
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HIGH PASS COAXIAL FILTERS
SHUNT L
SERIES C
COAXIAL
CONNECTOR
SEMI-LUMPED ELEMENTS EQUIVALENT CIRCUIT
Dr. Kawthar Zaki
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MICROSTRIP LOW PASS
FILTERS
METALIZED CIRCUIT PATTERN
DIELECTRIC SUBSTRATE OVER GROUND PLANE
Dr. Kawthar Zaki
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BAND PASS COAXIAL FILTERS
‘DUMBELL’ BANDPASS COAXIAL FILTER
DIELECTRIC
SLEEVE
l/4 RESONATORS
SERIES CAPACITORS
Dr. Kawthar Zaki
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PARALLEL COUPLED LINES
l/4
l/4
l/4
l/4
CENTER CONDUCTOR
PATTERN
OUTER CONDUCTOR
& HOUSING
DIELECTRIC
SHEET
SUSPENDED SUBSTRATE LINE
OVERLAY COUPLED LINES
• MICROSTRIP PRINTED CIRCUIT REALIZATION
• RECTANGULAR COUPLED BARS FOR WIDER BANDWIDTHE & HIGHER Q’S
• POSSIBLE SUSPENDED SUBSTRATE REALIZATION (HIGHER Q)
Dr. Kawthar Zaki
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BANDPASS END COUPLED MICROSTRIP
FILTERS
METALIZED CIRCUIT PATTERN l/2
RESONATORS
DIELECTRIC SUBSTRATE OVER GROUND PLANE
Dr. Kawthar Zaki
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INTERDIGITAL & COMBLINE
BAND PASS FILTERS
OPEN CIRCUIT END
COUPLING IRIS
SHORT CIRCUIT END
TOP VIEW
Dr. Kawthar Zaki
INNER CONDUCTORS OF
COAXIAL RESONATORS
SIDE VIEW
33
WAVEGUIDE FILTERS
INDUCTIVE WINDOWS (MODERATE BANDWIDTHS)
DIRECT COUPLED USING IRIS (NARROW BANDWIDTHS)
Dr. Kawthar Zaki
34
RIDGE WAVEGUIDE FILTERS
Dr. Kawthar Zaki
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DUAL MODE CIRCULAR
WAVEGUIDE FILTERS
TUNING SCREWS
INPUT
IRIS
OUTPUT
IRIS
5
Dr. Kawthar Zaki
2
3
6
4
1
36
Dual Mode Dielectric or Conductor Loaded
Resonator Filter
Dielectric or Conductor Loading
Input Coax Probe
Output Coax Probe
6
5
Dr. Kawthar Zaki
2
3
4
1
37
Dual Mode Dielectric or Conductor Loaded
Resonator Filter in Rectangular Enclosure
M12
M23
M36
M14
M56
M67
M34 M45
M78
M58
8-Pole Dual Mode Longitudinal Dielectric or Conductor Loaded
Resonator Filter in Rectangular Enclosure
Dr. Kawthar Zaki
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