1. High-Q Tunable Dielectric Resonator Filters
Raafat R. Mansour
Microwave Magazine, IEEE Oct Issue:
微波工程
碩通二甲
M98S0107
涂紹桓

2. 目錄 前言 簡介 研究 結論 心得

3. 前言
High-performance radio frequency (RF) tunable fi lters are needed in reconfi gurable systems to facilitate effi cient utilization of the available frequency spectrum.
They are in demand in front-end receivers for suppression of interfering signals and for relaxation of oscillator phase noise and dynamic range requirements.

4. 簡介
The availability of high-Q tunable filters may also have a significant impact on production cost and delivery schedule in some communication systems.
The ideal tunable filter must exhibit the following features: high loaded-Q value, wide tuning range, high tuning speed, good linearity, high power handling capability, small in size and mass, and high reliability.

5. Why Dielectric Resonator Filters
Figure 1 shows the relative insertion loss and size of typical microwave resonators.
The estimated range of unloaded Q values for each resonator category at 5 GHz is also shown in the same figure.
There is a wide range of resonator configurations under each resonator category.

6. Why Dielectric Resonator Filters
Figure 1. Relative insertion loss and size for various RF resonators
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

7. Why Dielectric Resonator Filters
If reconfigurable RF filters are ever employed in wireless base stations and satellite systems, tunable dielectric resonator filters stand to be the optimum solution.

8. Why Dielectric Resonator Filters
If reconfigurable RF filters are ever employed in wireless base stations and satellite systems, tunable dielectric resonator filters stand to be the optimum solution.

9. Why Dielectric Resonator Filters
High Q dielectric materials with dielectric constants ranging from 20 to 90, are now commercially available from various manufacturers.
Dielectric resonators with er530 are commercially available with a Q 3 f product values of 100,000, i.e., an unloaded Q value of about 50,000 can be achieved at 2.0 GHz.

10. Why Dielectric Resonator Filters
Figure 2. A typical dielectric resonator filter (BLMicrowave, used with permission)
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

11. Why Dielectric Resonator Filters
Figure 3. Novel dielectric resonator filters made on a high-K substrate
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

12. Filters Employing Mechanical or Piezoelectric Actuators
Figure 4. Tunable dielectric resonators disclosed in a 1987 patent by Wakino. (a) The tuning element is a piezoelectric actuator and (b) the tuning element is a piezoelectric attached to a tuning dielectric disk
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

13. Filters Employing Mechanical or Piezoelectric Actuators
Figure 5. The use of a second smaller dielectric resonator to improve the tuning range
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

14. Filters Employing Mechanical or Piezoelectric Actuators
Figure 6 shows a seven-pole filter version employing the concept [24] .
Dielectric plugs (basically, dielectric resonators of smaller dimensions) are used to tune the resonant frequency of the cone-shaped hollow resonator.
The dielectric plugs are brought in and out of the cone-shaped resonator by screws.

15. Filters Employing Mechanical or Piezoelectric Actuators
Figure 6. A cone-shaped dielectric resonator filter tuned manually using dielectric plugs (other dielectric resonators). (a) The dielectric plug is outside the shaped cone resonator, and (b) the dielectric plug is inside the cone-shaped resonator
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

16. Filters Employing Mechanical or Piezoelectric Actuators
Figure 7 illustrates the experimental results obtained from the filter shown in Figure 6 .
Excellent experimental results were obtained using this concept. The results show a filter having a 20 MHz bandwidth tuned by 50 MHz in center frequency.
The filter is retuned to have a bandwidth of 5 MHz and is then tuned in center frequency by 50 MHz.
The structure allows manual tuning of both bandwidth and center frequency.

17. Filters Employing Mechanical or Piezoelectric Actuators
Figure 7. The experimental results of the cone-shaped resonator shown in Figure 5
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

18. Filters Employing Mechanical or Piezoelectric Actuators
Figure 8. A dual-mode tunable dielectric-resonator filter, tuned by piezoelectric actuators (a) Side view and (b) top view. The screw at the angle a is used to couple the dual modes
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

19. Filters Employing Mechanical or Piezoelectric Actuators
Figure 9. A two-pole dual-mode dielectric resonator filter implemented using piezoelectric actuators
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

20. Filters Employing Mechanical or Piezoelectric Actuators
Figure 10. A dielectric resonator operating in the TM mode
Figure 11. The tuning range and the unloaded Q versus gap for the dielectric resonator shown in Figure 9
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

21. MEMS-Based Tunable Dielectric Resonator Filters
Figure 12. Piezoelectric tuning mechanisms
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

22. MEMS-Based Tunable Dielectric Resonator Filters
Figure 13. Filter schematic and HFSS simulation results
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

23. MEMS-Based Tunable Dielectric Resonator Filters
Figure 14. Picture of the fabricated filter
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

24. MEMS-Based Tunable Dielectric Resonator Filters
Figure 15. The measured dieletric resonator filter shown in Figure 14 with no tuning
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

25. MEMS-Based Tunable Dielectric Resonator Filters
Figure 16. The measured tunable dielectric-resonator filter shown in Figure 14
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

26. MEMS-Based Tunable Dielectric Resonator Filters
Figure 17. Q of a dielectric resonator operating in TME versus Q of an evanescent-mode resonator (metallic resonator) having the same dimensions
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

27. MEMS-Based Tunable Dielectric Resonator Filters
Figure 18. Schematic of the proposed tuning structure
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

28. MEMS-Based Tunable Dielectric Resonator Filters
Figure 19. Frequency shift and Q as a function of the
tuning gap, when the tuning disk diameter is fixed
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

29. MEMS-Based Tunable Dielectric Resonator Filters
Figure 20. Frequency shift and Q as a function of the tuning disk diameter when the tuning gap is 0.1 and 0.2 mm
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

30. MEMS-Based Tunable Dielectric Resonator Filters
Figure 21. HFSS simulation results of a three-pole dielectric resonator filter tuned to different frequencies (without loss)
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

31. MEMS-Based Tunable Dielectric Resonator Filters
Figure 22. MEMS tuning elements: (a) a solid circular tuning disk with warpage and (b) a hexagonal tuning disk without warpage
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

32. MEMS-Based Tunable Dielectric Resonator Filters
One key challenge in the design of tunable filters is to maintain a constant filter bandwidth and a reasonable return loss performance over the tuning range.

33. MEMS-Based Tunable Dielectric Resonator Filters
Figure 23. Proposed three-pole tunable dielectric resonator filter: (a) the top cover with MEMS tuning elements, (b) the filter body, and (c) the assembled filter
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

34. MEMS-Based Tunable Dielectric Resonator Filters
Figure 24. Comparison of the measured results of the proposed tunable dielectric resonator filter for different tuning states
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

35. MEMS-Based Tunable Dielectric Resonator Filters
Figure 25. A tunable dielectric resonator using a disk integrated with switches
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

36. MEMS-Based Tunable Dielectric Resonator Filters
Figure 26. The magnetic field distribution with (a) the switches OFF and (b) the switches ON
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

37. MEMS-Based Tunable Dielectric Resonator Filters
Figure 27. A two-pole filter dieletric resonator filter with two disks integrated in the cover and with integrated switches
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

38. MEMS-Based Tunable Dielectric Resonator Filters
Table 1 compares the theoretical resonant frequency and Q of the resonator without the disk and with the disk with switches in the ON and OFF state.
The switches here are simulated in HFSS using a metallic wire.
The presence of the disk in proximity of the resonator reduces its Q by around 40%.

39. MEMS-Based Tunable Dielectric Resonator Filters
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

40. MEMS-Based Tunable Dielectric Resonator Filters
Figure 28. The HFSS simulation results of the filter shown in Figure 27
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

41. MEMS-Based Tunable Dielectric Resonator Filters
Figure 29. The measured results of the filter shown in Figure 27
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

42. Magnetically Tuned Dielectric Resonators
Magnetically tuned dielectric resonators have been reported in [37] – [38] .
The principle is to control the magnetic field pattern in the vicinity of the dielectric resonator using ferrite material, which in turn results in a change of the resonant frequency.

43. Figure 30. A schematic of a tunable dielectric resonator filter with (a) axially magnetized ferrite and (b) circumgenntically magnetized ferrite
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

44. Magnetically Tuned Dielectric Resonators
Figure 31. Picture of a two-pole ferrite tunable dielectric resonator filter, axially magnetized
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

45. Magnetically Tuned Dielectric Resonators
Figure 32. Picture of a tunable dielectric resonator filter with a circumferentially magnetized ferrite
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

46. Magnetically Tuned Dielectric Resonators
Figure 33. Resonant frequency and Q of the ferrite tunable dielectric resonator filter shown in Figure 32
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

47. Varactor Tuned Dielectric Resonators
Figure 34. A varactor-tuned dielectric resonator. Thevaractors are integrated on a substrate placed on top of thedielectric resonator.
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

48. Varactor Tuned Dielectric Resonators
Figure 35. A varactor-tuned dielectric resonator filter.The varactors are integrated on a substrate placed in proximity of the dielectric resonator.
資料來源：Raafat R. Mansour . High-Q Tunable Dielectric Resonator Filters .
Microwave Magazine, IEEE Oct Issue:

49. Optically Tuned Dielectric Resonators
A dielectric resonator integrated with a photosensitive material was reported in [41] to demonstrate the possibility of tuning the dielectric resonator by optical means.

50. Impact of Spurious Performance and Temperature Drift on Tuning Range
the limited spurious performance of dielectric resonators should not limit the use of tunable dielectric resonator filters in such applications.
The overall temperature drift of the dielectric resonator filter is determined by the temperature coefficient of the dielectric resonator, the support structure and the thermal expansion coefficient of the enclosure.
The temperature drift problem exists in all other known tunable filters technologies.

51. Constant Bandwidth and Return Loss Performance over the Tuning Range
Tunable dielectric resonator filters can potentially address wireless and satellite applications that require very high Q values with a limited tuning range.

52. 結論
Tunable dielectric resonator filters can potentially address wireless and satellite applications that require very high Q values (4,000 and up) with a limited tuning range (less than 15%).

53. 心得
這篇PAPER是將多篇論文整理然後做實驗模擬，包含了理論及實驗很有參考價值，不過就如發表者所講的研究著重於部份標準，所以在期他方向還有很大的發展空間。