Tunable microwave filtering device with dielectric resonator, and applications

• US 4,835,498 A
• Filed: 06/06/1988
• Issued: 05/30/1989
• Est. Priority Date: 06/09/1987
• Status: Expired due to Fees

• Current Assignee: Thomson-CSF (Thales SA)
• Original Assignee: Thomson-CSF (Thales SA)
• Inventors: Denis, Gilles, Rouger, Jean-Michel, Liabeuf, Bernard
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US07/202,578
• Time in Patent Office: 358 Days
• Field of Search: 333/202, 333/204, 333/205, 333/219, 333/219.1, 333/246, 333/235, 333/222, 333/223, 331/96, 331/101, 331/107 DP, 331/107 SL, 331/117, 329/116, 329/120
• US Class Current: 329/354
• CPC Class Codes: H01P 7/10 Dielectric resonators
• CPC Class Codes: H03B 5/1841 the frequency-determining element being a strip line resonator H03B5/1805, H03B5/1817, H03B5/1864 and H03B5/1882 take precedence
• CPC Class Codes: H03B 5/1864 the frequency-determining element being a dielectric resonator

Abstract

A tunable, microwave filtering device comprises a microstrip line, a dielectric resonator capable of being coupled to the microstrip line, a coplanar line capable of being coupled to the resonator, an active element, such as a varactor for example, mounted on the coplanar line, the variable impedance of which enables the frequency tuning of the device. The invention can be applied to the making of a tunable microwave frequency discriminator, the making of a microwave oscillator and the frequency stabilization of a tunable oscillator.

Claims

1. A tunable microwave filtering device comprising:

a first microstrip line comprising a ground plate;

a dielectric resonator coupled to said microstrip line;

an active element coupled to said dielectic resonator, the variable impedance of said active element enabling the frequency tuning of the device;

a coplanar line cut up in said ground plate and coupled to said resonator, the active element being mounted on said coplanar line.

2. A device according to claim 1 wherein the active element is a varactor to which a variable voltage is applied, this variation enabling the modification of the impedance of the varactor.

3. A device according to claim 2 wherein:

said dielectric resonator is located beside said first microstrip line;

said coplanar line, is substantially perpendicular to said first microstrip line and is located near said resonator, the device obtained constituting, in transmission, a tunable, band rejection filter.

4. A device according to claim 2 wherein:

said dielectric resonator is located beside said first microstrip line;

said coplanar line, said ground is substantially parallel to said first microstrip line and located near said resonator,

the device obtained constituting, in transmission, a tunable, band rejection filter.

5. A device according to claim 3 further comprising a second microstrip line substantially parallel to said first microstrip line, the device thus obtained constituting:

in transmission, a tunable band rejection filter,

for a signal injected along said first microstrip line and going out through said second microstrip line, a tunable pass-band filter.

6. Tunable microwave oscillator with dielectric resonator, said oscillator comprising a device as in any one of claims 1-4.

7. Filtering device according to claim 3 further comprising:

a second microstrip line, substantially parallel to said first microstrip line, substantially parallel to said first microstrip line, and coupled to said resonator;

the output signals of the first and of the second microstrip lines being combined by diode detection means in such a way that a frequency-amplitude characteristic of a discriminator may be obtained.

8. Tunable microwave oscillator, stabilized in frequency by a tunable discriminator, said oscillator comprising;

a first microstrip line comprising a ground plate;

a dielectric resonator coupled to and located beside said first microstrip line;

a coplanar line, cut up in said ground plate, substantially perpendicular to said first microstrip line, and coupled to located near said resonator;

a varactor mounted on said coplanar line, to which a variable voltage is applied, such a variation of voltage enabling the frequency tuning of said filtering device;

a second microstrip line, substantially parallel to said first microstrip line and coupled to said resonator;

diode detection means combining the output signals of said first and second microstrip lines, in such a way that a frequency amplitude characteristic of a discriminator may be obtained;

so as to enable the stabilization of the oscillator throughout the tuning band of said oscillator by means of a shift in frequency of the frequency-amplitude characteristic of said discriminator, said shift in frequency of said characteristic being obtained through the control of the voltage applied to said varactor.