1 HIGH QUALITY FERRITE-LOADED DIELECTRIC RESONATOR TUNABLE FILTERS HIGH QUALITY FERRITE-LOADED DIELECTRIC RESONATOR TUNABLE FILTERS A. Abramowicz, J. Krupka, K. Derzakowski

2 Outline of presentation Permeability of ferrite material Relationship between tuneability Q-factor and permeability components Tuneable resonators containing magnetized ferrite elements Analysis of filter structures Filter with axially magnetized rods Filter with circumferentially magnetized ferrite discs Filter made of ferrite resonators

3 Permeability of ferrite material Scalar properties (no bias) Tensor properties (under bias)

4 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

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

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

7 Permeability tensor Uniform bias (axial) Uniform bias (circumferential)

8 Related quantities Permittivities for circularly polarized waves

9 Dielectric resonators used for measurements of all permeability tensor components

10 Real parts of permeability tensor for YIG

11 Imaginary parts of permeability tensor for YIG

12 Relationship between tuneability and Q- factor

13

14 Figures of merit for axially magnetized ferrite rods made of commercially available materials

15 Dielectric resonator containing axially magnetized ferrite rod

16 Experimental tuning characteristics and Q-factors for TE 01 mode dielectric resonator with ferrite rod

17 Dielectric resonator containing circumferentially magnetized ferrite discs

18 Photograph of tuneable dielectric resonator containing circumferentially magnetized ferrite discs

19 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

20 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 housing iris Analysis of filter structures

21 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 f e computed for PEC in the symmetry plane f o computed for PMC in the symmetry plane Analysis of filter structures

22 Filter structure for FDTD simulator - mesh details Analysis of filter structures

23 Filter structure for FDTD simulator - 3D view Analysis of filter structures

24 TE 011 mode H z field component Analysis of filter structures

25 Hy (left) and Hx (right) field components Analysis of filter structures

26 FDTD computations of the coupling coefficient versus height of the iris

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

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

29 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

30 Photograph of disassembled filter containing circumferentially magnetized ferrite discs

31 Photograph of the assembled filter with tuning coil

32 Transmission coefficient versus tuning current

33 Return losses versus tuning current

34 Insertion losses versus tuning current

35 Unloaded Q-factor versus tuning current

36 Broad frequency band response

37

38 improvement in modes separation - MM and RRM -copper cylinder at the resonator axis -smaller ferrite discs mixed type resonators - DR + TEM resonators Optimization of spurious response

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

40 Measured transmission characteristic in wide frequency range. Optimization of spurious response

41 Housing of a new filter containing TEM resonators. Optimization of spurious response

42 Schematic diagram of filter made of ferrite resonators

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

44 Tuning characteristics of three-pole filter made of ferrite resonators

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

46 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 MIKON2004, 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