HIGH QUALITY FERRITE-LOADED HIGH QUALITY FERRITE-LOADED DIELECTRIC RESONATOR TUNABLE DIELECTRIC RESONATOR TUNABLE

FILTERSFILTERS

A. Abramowicz, J. Krupka, K. Derzakowski

Outline of presentation

Permeability of ferrite material Relationship between tuneability Q-factor and permeability components Tuneable resonators containingmagnetized ferrite elementsAnalysis of filter structures Filter with axially magnetized rodsFilter with circumferentially magnetized ferrite discs Filter made of ferrite resonators

Permeability of ferrite material

• Scalar properties (no bias)

• Tensor properties (under bias)

Dielectric resonator used for measurements of scalar complex permeability of ferrite rods

Coaxial line holder used for measurements of scalar complex permeability of round robin ferrite samples

Results of broad frequency band measurements of scalar permeability (real part)

Results of broad frequency band measurements of scalar permeability (imaginary part)

Permeability tensor

z

j

j

00

0

0

0

0

00

0

0

j

j

Uniform bias (axial)

Uniform bias (circumferential)

Related quantities

2

Permittivities for circularly polarized waves

Dielectric resonators used for measurements of all permeability tensor components

Real parts of permeability tensor for YIG

0.0

0.2

0.4

0.6

0.8

1.0

0 20 40 60 80 100 120 140 160

z

Re()

Hext

(kA/m)

Imaginary parts of permeability tensor for YIG

-1.0 10-3

-5.0 10-4

0.0 100

5.0 10-4

1.0 10-3

1.5 10-3

0 20 40 60 80 100 120 140 160

z

Im()

Hext

(kA/m)

Relationship between tuneability and Q-factor

mpf

f

2

1

0

2

2

)(V

Vfm

dvHv

dvH

p

)tan/(1 mm pQ

tan

1

max

__

meritoffigQ

Relationship between tuneability and Q-factor

)2/( max__ f

fQQ meritoffigm

11110

cme QQQQ

0

2

2

1

)(

tan

V

Vfe

eee

dvHv

dvH

p

pQ

S

s

Vc

dsHR

dvH

Q 2

2

Figures of merit for axially magnetized ferrite

rods made of commercially available materials

Dielectric resonator containing axially magnetized ferrite rod

Experimental tuning characteristics and Q-factors

for TE01 mode dielectric resonator with ferrite rod

2090.000

2100.000

2110.000

2120.000

2130.000

2140.000

-5 -4 -3 -2 -1 0 1 2 3 4 5

Ms=55 mT

(from 5A to -5A)(from -5A to 5A)

f (MHz)

I(A)0.000

1000.000

2000.000

3000.000

4000.000

0 1 2 3 4 5

Ms=55 mT

Q

I(A)

Dielectric resonator containing circumferentially magnetized ferrite discs

Photograph of tuneable dielectric resonator containing circumferentially magnetized ferrite

discs

Tuning characteristics of TE01 mode dielectric resonator containing circumferentially magnetized

ferrite discs and corresponding hysteresis loop. Material G-510 df=39.3 mm, hf=6.1 mm

0

10

20

30

40

50

0 100 200 300 400 500 600 700 800

B(mT)

H(A/m)

2260

2265

2270

2275

2280

2285

0 100 200 300 400 500

f(MHz)

H(A/m)

For high quality filters like a channel filter with 5 MHz bandwidth or high-selectivity receive front-end filter the needed quality

factor of resonators implies the following filter structure.

resonator

housingiris

Analysis of filter structures

The filter structure has been analyzed using

3D FDTD simulator (QuickWave).

-parametrized object allowing easy change of dimensions has been created

-half of the structure has been analyzed taking advantage of the eigenfrequency method

fe computed for PEC in the symmetry plane

fo computed for PMC in the symmetry plane

22

22

oe

oe

ff

ffk

Analysis of filter structures

Filter structure for FDTD simulator - mesh details

Analysis of filter structures

Filter structure for FDTD simulator - 3D view

Analysis of filter structures

TE011 mode

Hz field component

Analysis of filter structures

Hy (left) and Hx (right) field components

Analysis of filter structures

FDTD computations of the coupling coefficient versus height of the iris

3035404550

iris he ight / m m

5

2

3

5

2

3

5

1 .00 E-3

1 .00 E-2

cou

plin

g c

oe

ffic

ien

t

Photograph of disassembled two dielectric resonator filter containing axially magnetized ferrite rods

Tuning characteristics of two-pole filter with axially magnetized ferrite rods

-50

-40

-30

-20

-10

0

2.18 2.2 2.22 2.24 2.26

|S21

|

|S11

|

f(GHz)

I=0

I=0

I=1.25 A

I=-0.5 A

I=0.5 A

Measured insertion loss of the filter tuned by ferrite rod. Current starts from 0.0 A and goes through 0.5 A,

1.25 A, 0 A, -0.5 A back to 0.0 A

-0.5 0.0 0.5 1.0 1.5D C current / A

0.6

0.8

1.0

1.2

1.4

1.6

Inse

rtio

n lo

ss

/ d

B

Photograph of disassembled filter containing circumferentially magnetized

ferrite discs

Photograph of the assembled filter with tuning coil

Transmission coefficient versus tuning current

-40

-35

-30

-25

-20

-15

-10

-5

0

2300 2310 2320 2330 2340 2350 2360 2370

|S21

|

(dB)

f(MHz)

(0 - 1.5) A

-30

-25

-20

-15

-10

-5

0

2300 2310 2320 2330 2340 2350 2360 2370

|S11

|

(dB)

f(MHz)

(0 - 1.5) A

Return losses versus tuning current

Insertion losses versus tuning current

0

0.1

0.2

0.3

0.4

0.5

0 0.5 1 1.5

IL(dB)

I(A)

Unloaded Q-factor versus tuning current

8000

9000

10000

11000

12000

13000

0 0.5 1 1.5

Q

I(A)

Broad frequency band response

-100

-80

-60

-40

-20

0

1.5 2 2.5 3 3.5

|S21

|

|S11

|

f(GHz)

improvement in modes separation - MM and RRM

-copper cylinder at the resonator axis

-smaller ferrite discsmixed type resonators - DR + TEM

resonators

Optimization of spurious response

2.28 2.29 2.30 2.31 2.32 2.33 2.34 2.35

frequency /G Hz

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0 s

11

&

s2

1

/dB

s11 - I = 0 A

s21 - I = 0 A

s11 - I = 1 .5 A

s21 - I = 1 .5 A

Measured S11 and S21 of the four resonator filter with mixed types of resonators (DR and TEM).

Optimization of spurious response

1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

frequency /G H z

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0S2

1 /

dB

Measured transmission characteristic in wide frequency range.

Optimization of spurious response

Housing of a new filter containing TEM resonators.

Optimization of spurious response

Schematic diagram of filter made of ferrite resonators

Photograph of three-pole filter made of ferrite resonators (YIG)

Tuning characteristics of three-pole filter made of ferrite resonators

Most of research work have been peformed under the project: TUNEABLE FILTERS BASED ON DIELECTRIC (TUF), project no.: GRD1-2001-40547sponsored by European Community

Related papers

•J. Krupka, A. Abramowicz and K. Derzakowski, „Magnetically Tunable Dielectric Resonators Operating at Frequencies about 2 GHz”, Journal of Physics D: Applied Physics, vol. 37, pp.379-384, Feb. 2004.•J. Krupka, A. Abramowicz and K. Derzakowski, “Magnetically Tunable Filters for Cellular Communication Terminals”, IEEE Trans.on MTT, vol.54, pp.2329-2335, June 2006   

• J. Krupka, A. Abramowicz and K. Derzakowski, „Magnetically tunable dielectric resonators operating at frequencies about 2 GHz”, p.31, The physics Congress 2003, 23-27 March, Edinburgh•Abramowicz, J. Krupka, and K. Derzakowski, “Triplet dielectric resonator filters with direct coupling”, Proc. of the International Conference on Electromagnetics in Advanced Applications, pp.143-146, Torino, Italy, September 8-12,2003.•K. Derzakowski, J.Krupka and A. Abramowicz,”Tunable dielectric resonator with circumferentially magnetized ferrite disks”, Int. Conference MIKON’2004, pp.1052-1055, Warszawa, May 17-19, 2004.•K. Derzakowski, J. Krupka and A. Abramowicz, “Magnetically tunable dielectric resonators and filters”, Proc of 34th European Microwave Conference, pp.1121-1124, Amsterdam 12-14 October, 2004