Claims
- 1. A strip dual mode filter in which a microwave is resonated and filtered, comprising:
- a closed loop-shaped strip line for resonating and filtering the microwave according to a characteristic impedance of the closed loop-shaped strip line, the closed loop-shaped strip line having an electric length equivalent to a wavelength of the microwave and having a uniform line impedance;
- input coupling means for transferring the microwave to a first coupling point of the closed loop-shaped strip line in electromagnetic coupling;
- a secondary microwave transmitting line for transmitting the microwave resonated and filtered in the closed loop-shaped strip line to change the characteristic impedance of the closed loop-shaped strip line, the secondary microwave transmitting line being coupled to second and third coupling points of the closed loop-shaped strip line in electromagnetic coupling, the second coupling point being spaced a half-wave length of the microwave apart from the first coupling point, and the third coupling portion being spaced a quarter-wave length of the microwave apart from the first coupling point; and
- output coupling means for outputting the microwave which is resonated and filtered in the closed loop-shaped strip line according to the characteristic impedance of the closed loop-shaped strip line changed by the secondary microwave transmitting line, the microwave being output from a fourth coupling point spaced a half-wave length of the microwave apart from the third coupling point in electromagnetic coupling, wherein
- the secondary microwave transmitting line comprises a feed-back circuit in which a phase of the microwave transferred from the second coupling point of the closed loop-shaped strip line shifts by a multiple of a half-wave length of the microwave to produce a feed-back microwave which is transferred to the third coupling point of the closed loop-shaped strip line, the input coupling means comprises a microwave receiver and an input coupling inductor for coupling the microwave receiver to the closed loop-shaped strip line in inductive coupling, and the output coupling means comprises a microwave transfer and an output coupling inductor for coupling the microwave transfer to the closed loop-shaped strip line in inductive coupling.
- 2. A filter according to claim 1 in which the input coupling inductor and the output coupling inductor are respectively formed of an inductor having a lumped inductance.
- 3. A filter according to claim 1 in which the input coupling inductor and the output coupling inductor are respectively formed of a narrow strip line having a distributed inductance.
- 4. A filter according to claim 1 in which the phase-shifting circuit comprises a strip line through which the microwave transmits.
- 5. A filter according to claim 1 in which the phase-shifting circuit comprises a lumped impedance element such as a capacitor or an inductor.
- 6. A filter according to claim 1 in which the phase-shifting circuit comprises a combination circuit of an amplifier and a strip line in which the phase of the microwave is corrected.
Priority Claims (5)
Number |
Date |
Country |
Kind |
4-153243 |
Jun 1992 |
JPX |
|
4-244373 |
Sep 1992 |
JPX |
|
4-244398 |
Sep 1992 |
JPX |
|
4-257799 |
Sep 1992 |
JPX |
|
4-326588 |
Dec 1992 |
JPX |
|
Parent Case Info
This application is a division of application Ser. No. 08/291,811 filed Aug. 17, 1994, now U.S. Pat. No. 5,479,142 which is a Divisional application of U.S. Ser. No. 08/071,112 filed Jun. 3, 1993 now U.S. Pat. No. 5,400,002.
US Referenced Citations (6)
Foreign Referenced Citations (5)
Number |
Date |
Country |
0532330 |
Mar 1993 |
EPX |
2248621 |
May 1975 |
FRX |
61-251203 |
Nov 1986 |
JPX |
62-298202 |
Dec 1987 |
JPX |
0001302 |
Jan 1989 |
JPX |
Non-Patent Literature Citations (3)
Entry |
1990 IEEE MTT-S International Microwave Symposium-Digest, vol. 1; May 8-10, 1990 Dallas, US; IEEE, New York, US, 1990; X.H. Jiao et al.: "Microwave frequency agile active filters for MIC and MMIC applications", pp. 503-506. |
IRE Transactions on Microwave Theory and Techniques, vol. 9, No. 7, Jul. 1961, New York, US; pp. 359-360; J.A. Kaiser "Ring network filter". |
"Miniature Dual Mode Microstrip Filters" by J.A. Curtis et al.; 1991 IEEE MTT-S Digest pp. 443-446. |
Divisions (2)
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Number |
Date |
Country |
Parent |
291811 |
Aug 1994 |
|
Parent |
71112 |
Jun 1993 |
|