Claims
- 1. A strip line filter for resonating and filtering a microwave, comprising;
- a series of one-wavelength loop-shaped strip line resonators respectively having a uniform line impedance for respectively resonating and filtering a microwave according to a first resonance mode in which electric voltages at both a first coupling point and a second coupling point spaced 180 degrees in electric length apart from the first coupling point are maximized and respectively resonating and filtering the microwave according to a second resonance mode in which electric voltages at both a third coupling point spaced 90 degrees in electric length apart from the first coupling point and a fourth coupling point spaced 180 degrees in electric length apart from the third coupling point are maximized, each of the one-wavelength loop-shaped strip line resonators having a first parallel coupling line between the first and third coupling points and a second parallel coupling line between the second and fourth coupling points, the second parallel coupling line of a one-wavelength loop-shaped strip line resonator arranged in an N-th stage (N is an integral number) being electromagnetically coupled to the first parallel coupling line of another one-wavelength loop-shaped strip line resonator arranged in an (N+1)-th stage to transfer the microwave between the one-wavelength loop-shaped strip line resonator arranged in the N-th stage and the one-wavelength loop-shaped strip line resonator arranged in the (n+1)-th stage;
- four open-end transmission lines connected to the first, second, third and fourth coupling points of each of the one-wavelength loop-shaped strip line resonators for electromagnetically influencing the microwave resonated in each of the one-wavelength loop-shaped strip line resonators, the open-end transmission lines having the same electromagnetic characteristics;
- a microwave inputting element for inputting the microwave to the first coupling point of a one-wavelength loop-shaped strip line resonator arranged in a first stage, the microwave input by the microwave inputting element being resonated according to the first resonance mode by stages and being transferred to a one-wavelength loop-shaped strip line resonator arranged in a final stage;
- an inter-stage coupling circuit for transferring the microwave resonated according to the first resonance mode from the second coupling point of the one-wavelength loop-shaped strip line resonator arranged in the final stage to the fourth coupling point of the one-wavelength loop-shaped strip line resonator arranged in the final stage, the microwave transferred by the inter-stage coupling circuit being resonated according to the second resonance mode by stages and being transferred form the one-wavelength loop-shaped strip line resonator arranged in the final stage to the one-wavelength loop-shaped strip line resonator arranged in the first stage; and
- a microwave outputting element for outputting the microwave resonated according to the second resonance mode in the one-wavelength loop-shaped strip line resonator arranged in the first stage.
- 2. A trip line filter according to claim 1 in which the first and second parallel coupling lines are respectively shorter than 90 degrees in electric length.
- 3. A strip line filter according to claim 1 in which the one-wavelength loop-shaped strip line resonators are respectively in a rectangular shape, the one-wavelength loop-shaped strip line resonators respectively have two first parallel lines longer than 90 degrees in electric length and two second parallel lines shorter than 90 degrees in electric length, the first and fourth coupling points are placed at the same first parallel line of each of the one wavelength loop-shaped strip line resonators, the second and third coupling points are placed at the other first parallel line of each of the one-wavelength loop-shaped strip line resonators, and the first and second parallel coupling lines are formed of the second parallel lines of each of the one-wavelength loop-shaped strip line resonators.
- 4. A strip line filter according to claim 3 in which a first electric length between a first midpoint placed in the middle of the first parallel coupling line and the first coupling point is equal to a second electric length between the first midpoint and the third coupling point, a third electric length between a second midpoint placed in the middle of the second parallel coupling line and the second coupling point is equal to a fourth electric length between the second midpoint and the fourth coupling point, and the first electric length is equal to the third electric length.
- 5. A strip line filter according to claim 3 in which a first electric length between a first midpoint placed in the middle of the first parallel coupling line and the first coupling point is longer than a second electric length between the first midpoint and the third coupling point, a third electric length between a second midpoint placed in the middle of the second parallel coupling line and the second coupling point is shorter than a fourth electric length between the second midpoint and the fourth coupling point, the first electric length is equal to the fourth electric length, and the second electric length is equal to the third electric length.
- 6. A strip line filter according to claim 3 in which a first electric length between a first midpoint placed in the middle of the first parallel coupling line and the first coupling point is shorter than a second electric length between the first midpoint and the third coupling point, a third electric length between a second midpoint placed in the middle of the second parallel coupling line and the second coupling point is shorter than a fourth electric length between the second midpoint and the fourth coupling point, the first electric length is equal to the third electric length, and the second electric length is equal to the fourth electric length.
- 7. A strip-line filter according to claim 1 in which the microwave inputting element is formed of a parallel coupling strip line arranged in parallel to a strip line of the one-wavelength loop-shaped strip line resonator arranged in the first stage, and the microwave outputting element is formed of a parallel coupling strip line arranged in parallel to a strip line of the one-wavelength loop-shaped strip line resonator arranged in the first stage.
- 8. A strip-line filter according to claim 1 in which the inter-stage coupling circuit is formed of a pair of paralleled strip lines coupling to each other.
Priority Claims (3)
Number |
Date |
Country |
Kind |
5-247845 |
Oct 1993 |
JPX |
|
5-325070 |
Dec 1993 |
JPX |
|
6-189496 |
Aug 1994 |
JPX |
|
Parent Case Info
This is a division of application Ser. No. 08/980,478 filed Nov. 28, 1997 now U.S. Pat. No. 5,880,656, which is a divisional application of Ser. No. 08/775,772 filed Dec. 31, 1996 now U.S. Pat. No. 5,748,059, which is a divisional application of Ser. No. 08/598,541, filed Feb. 8, 1996 now U.S. Pat. No. 5,684,440, which in turn is a divisional application of Ser. No. 08/317,505 filed Oct. 4, 1994 now U.S. Pat. No. 5,534,831.
US Referenced Citations (5)
Foreign Referenced Citations (4)
Number |
Date |
Country |
0573985A1 |
Dec 1993 |
EPX |
2248621 |
May 1975 |
FRX |
3-228402 |
Oct 1991 |
JPX |
2222312A |
Feb 1990 |
GBX |
Non-Patent Literature Citations (4)
Entry |
"Miniature Dual Mode Microstrip Filters" by Curtis et al. 1991 IEEE MTT-S Digest; pp. 443-446. |
"Excitation Methods of Orthogonal Resonant Modes for the Stripline Ring Resonator and their Application to Filtering Devices" by M. Fujimura et al.; The Institute of Electronics Information and Communication Engineers; Technical Report of IEICE. MW92-115 (1992-12); pp. 15-22. |
IEEE Proceedings H. Microwaves, Antennas & Propagation, vol. 138, No. 4, Aug. 1991, Stevenage GB, pp. 383-385, S. H. Al-Charchafchi et al., "Study of Varactor tuned Microstrip Rhombic Resonators". |
20th European Microwave Conference-Proceedings 10-13 Sept. 1990, Budapest, HU, Microwave Exhibitions and Publishers Ltd., Tunbridge Wells, GB, 1990, pp. 901-906, M. Guglielmi et al. "Experimental Investigation of Dual-Mode Microstrip Ring Resonators". |
Divisions (4)
|
Number |
Date |
Country |
Parent |
980478 |
Nov 1997 |
|
Parent |
775772 |
Dec 1996 |
|
Parent |
598541 |
Feb 1996 |
|
Parent |
317505 |
Oct 1994 |
|