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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