TM110-MODE RESONATORS: Simple Configurations …jbornema/Workshops/04esa-bar.pdf · International Workshop on Microwave Filters – ESA – CNES - September 2004 TM110-MODE RESONATORS:

International Workshop on Microwave Filters – ESA – CNES - September 2004

TMTM110110--MODE RESONATORS:MODE RESONATORS:Simple ConfigurationsSimple Configurations

For Highly Flexible Waveguide For Highly Flexible Waveguide Filter DesignsFilter Designs

Jens BornemannDepartment of Electrical and Computer Engineering

University of Victoria, Victoria, BCCanada V8W 3P6

Smain AmariDepartment of Electrical and Computer Engineering

Royal Military College, Kingston, ONCanada K7K 7B4

Uwe RosenbergMarconi Communications GmbH

D-71520 Backnang, Germany

OutlineOutline

Motivation

TM110-Mode Resonators

Design Guidelines

Design Results

Non-Resonating Node Model

Design Variations

Conclusions

MotivationMotivation

Find a waveguide filter configuration

which allows the number and locations of transmission zeros to be as flexible as possible,

whose topology is independent of the number and locations of transmission zeros,

which leads to a relatively compact design,

which can be manufactured by standard waveguide fabrication techniques,

which does not require post-assembly tuning.

TMTM110110--Mode Resonators Mode Resonators -- AdvantagesAdvantages

Resonances are based on TM110-mode cavities allowing lower-order modes to generate cross/by-pass coupling.

The maximum number of transmission zeros equals the number of TM110-mode cavities.

The locations of transmission zeros are arbitrary, and simple design guidelines dictate their position with respect to the passband.

Each transmission zero is independently controlled as each resonance is capable of creating its own transmission zero.

The filter topology is in-line and, therefore, ideally suited to fit standard waveguide manufacturing technologies.

Due to the TM110-mode operation, the cavities are short. An N-pole TM110-mode filter usually requires less space than a comparable dual-mode filter based on TE101/011 modes.

TMTM110110--Mode Resonators Mode Resonators -- DisadvantageDisadvantage

Cascaded TM110-mode cavities cannot be designed by standard coupling matrices because the standard inter-resonator coupling matrix formulation fails to capture the physical interactions of fields and modes involved.

Therefore, a new coupling scheme based on so-called non-resonant nodes is developed and presented.

TMTM110110--Mode ResonatorsMode Resonators

22c

011r

22c

101r

22c

110r

c1

b1

2v

)TE(f

c1

a1

2v

)TE(f

b1

a1

2v

)TM(f

+=

+=

+=

Resonances

Cavity dimensions a, b, c selected such that- TM110 resonates- TE10 , TE01 do NOT resonate

a

b

c

Cavity

TMTM110110--Mode Resonator Mode Resonator ––TheThe SingletSingletCoupling MechanismCoupling Mechanism

Coupling is predominantly magnetic. An incoming TE10mode excites both TE10 and TM11 in the cavity.

TE10Direct and bypass coupling in phase

Transmission zero BELOWBELOW passband

Direct and bypass coupling out of phase

Transmission zero ABOVEABOVE passband

TE10

Design GuidelinesDesign Guidelines – Single Cavity1. Transmission Zero Below Passband

22 24 26 28 30 32 34 36 38 40f/GHz

-40

-30

-20

-10

0

dB

|S11|

|S21|

S L

( )SL 10M TE

( )1 110R TM

2. Transmission Zero Above Passband

22 24 26 28 30 32 34 36 38 40f/GHz

-40

-30

-20

-10

0

dB

|S11|

|S21|

S L

( )SL 10M TE

( )1 110R TM

3. No Transmission Zero

22 24 26 28 30 32 34 36 38 40f/GHz

-40

-30

-20

-10

0

dB

|S11|

|S21|

Design GuidelinesDesign Guidelines – Two Cavities1. Two Transmission Zeros Below Passband

22 24 26 28 30 32 34 36 38 40f/GHz

-80

-60

-40

-20

0

dB

|S11|

|S21|

2. Two Transmission Zeros Above Passband

22 24 26 28 30 32 34 36 38 40f/GHz

-80

-60

-40

-20

0

dB|S11|

|S21|

3. Two Transmission Zeros, One Below, One Above Passband

22 24 26 28 30 32 34 36 38 40f/GHz

-80

-60

-40

-20

0

dB |S11|

|S21|

4. No Transmission Zeros

22 24 26 28 30 32 34 36 38 40f/GHz

-80

-60

-40

-20

0

dB

|S11|

|S21|

Design Results Design Results - Filter ExamplesFour-Pole Filter With Chebyshev Response

25 26 27 28 29 30f/GHz-120

-100

-80

-60

-40

-20

0

dBCIET

MMT

Four-Pole Filter With Elliptic-Function-Type Response

25 26 27 28 29 30f/GHz-120

-100

-80

-60

-40

-20

0

dBCIET

MMT

MiCIAN

Four-Pole Filter WithThreeThree Transmission Zeros BelowBelow Passband

23 25 27 29 31f/GHz-140

-120

-100

-80

-60

-40

-20

0

dB

CIET

MMT

Four-Pole Filter WithFourFour Transmission Zeros BelowBelow Passband

22 24 26 28 30 32 34 36 38 40f/GHz

-140

-120

-100

-80

-60

-40

-20

0

dBCIET

MMT

Four-Pole Filter WithFourFour Transmission Zeros AboveAbove Passband

22 24 26 28 30 32 34 36 38 40f/GHz

-140

-120

-100

-80

-60

-40

-20

0dB

CIET

MMT

MeasurementMeasurement(cutter radius included using (cutter radius included using µµWaveWave Wizard)Wizard)

22 24 26 28 30 32 34 36 38 40f/GHz

-120

-100

-80

-60

-40

-20

0

dB

computed

measured

measured insertion loss less than 0.4dB over 700 MHz bandwidth

Coupling Scheme for Cascaded Coupling Scheme for Cascaded SingletsSinglets

S LSLM

1R

S LSLM

1R

S LSLM

1R

S

1R

L

3R2R

Non-Resonating Nodes (NRN’s)

NonNon--Resonating Node Model (NRNM)Resonating Node Model (NRNM)

Conventional DesignConventional Design[changing a single cross-coupling moves all transmission zeros]

10.0 10.5 11.0 11.5 12.0 12.5 13.0f/GHz

-120

-100

-80

-60

-40

-20

0

dB

S

L +

- ++0.0000 1.3167 0.0000 -0.0303

1.3167 0.0000 1.9272 0.0000M

0.0000 1.9272 0.0000 1.3167-0.0303 0.0000 1.3167 0.0000

⎡ ⎤⎢ ⎥⎢ ⎥=⎢ ⎥⎢ ⎥⎣ ⎦

Design with Singlets[changing a single bypass-coupling moves only one transmission zero]

22 24 26 28 30 32 34 36f/GHz

-100

-80

-60

-40

-20

0

|S11

|, |S

21|

/ dB

Pos 2

Pos 1 unaffected

transmission zero

Pos 1

Pos 2

NonNon--Resonating Node Model (NRNM)Resonating Node Model (NRNM)

1Ω 1Ω

s s jB4

jB1

jB2

jB3 jB5

K12 K23 K34 K45

K13 K35

resonator

LoadSource

non-resonating node

resonator

⎥⎥⎥⎥⎥⎥

⎦

⎤

⎢⎢⎢⎢⎢⎢

⎣

⎡

−−

=

0000.07668.12709.00000.00000.07668.16058.26932.10000.00000.02709.06932.18124.07314.01584.00000.00000.07314.04101.10340.10000.00000.01584.00340.10000.0

M

Design VariationsDesign Variations: Add a Resonant Iris

22 24 26 28 30 32 34 36 38 40f/GHz

-120

-100

-80

-60

-40

-20

0

dB|S11|

|S21|

Three-pole filter: 2 TM110 cavities + resonant iris

-100

-80

-60

-40

-20

0

22 28 34 40Frequency / GHz

s11,

s21

, d

B

—— calculated

—— measured

(cutter radius included (cutter radius included usingusing µµWaveWave Wizard)Wizard)

Seven-pole Quasi-Highpass Filter:3 TM110 cavities + four resonant irises

9 11 13 15 17 19 21f / GHz

-80

-60

-40

-20

0

|S|___dB

|S11| computed

|S21| computed

|S11| measured

|S21| measured

ETH Zürich

ConclusionsConclusions

Cascaded TM110-mode resonators offer an attractive solution for in-line waveguide bandpass filters with arbitrarily located transmission zeros.

These filters have simple geometriessimple geometries, which lend themselves to design by accurate and fast CAD tools, but retain a high flexibilityhigh flexibility as to the number and locations of transmission zeros.

A new coupling matrix approach based on the Non-Resonant Node Model aids in the design of the filters.

Excellent agreement with measured dataagreement with measured data is demonstrated.

TM110-mode resonators are shorter than comparable cavities based on half-wavelength resonances.

Further ReadingFurther Reading

U. Rosenberg, S. Amari and J. Bornemann, “Inline TM110-mode filters with high design flexibility by utilizing bypass couplings of non-resonating TE10/01 modes”, IEEE Trans. Microwave Theory Tech., Vol. 51, pp. 1735-1742, June 2003.

U. Rosenberg, S. Amari and J. Bornemann, “Mixed-resonance compact in-line pseudo-elliptic filters”, in 2003 IEEE MTT-S Int. Microwave Symp. Dig., pp. 479-482, Philadelphia, USA, June 2003.

S. Amari, U. Rosenberg and J. Bornemann, “Singlets, cascaded singlets and the non-resonating node model for advanced modular design of elliptic filters”, IEEE Microwave Wireless Component Lett., Vol. 14, pp. 237-239, May 2004.

S. Amari, U. Rosenberg and J. Bornemann, “A novel approach to dual and triple-mode pseudo-elliptic filter design”, in 34th European Microwave Conf., Amsterdam, The Netherlands, Oct. 2004.

U. Rosenberg, S. Amari, J. Bornemann and R. Vahldieck, “Compact pseudo-highpass filters formed cavity and iris resonators”, in 34th European Microwave Conf., Amsterdam, The Netherlands, Oct. 2004.