(19)
(11) EP 0 508 733 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
13.01.1993 Bulletin 1993/02

(43) Date of publication A2:
14.10.1992 Bulletin 1992/42

(21) Application number: 92303091.0

(22) Date of filing: 08.04.1992
(51) International Patent Classification (IPC)5: H01P 1/205
(84) Designated Contracting States:
CH DE DK FR GB IT LI SE

(30) Priority: 12.04.1991 FI 911795

(71) Applicant: LK-PRODUCTS OY
SF-90440 Kempele (FI)

(72) Inventors:
  • Nappa, Pauli
    SF-90450 Oulu (FI)
  • Salonen, Keijo
    SF-90250 Oulu (FI)

(74) Representative: Frain, Timothy John 
Patent Department Nokia Mobile Phones St Georges Court St Georges Road
Camberley, Surrey GU15 3QZ
Camberley, Surrey GU15 3QZ (GB)


(56) References cited: : 
   
       


    (54) Adjustable ceramic filter


    (57) A filter comprises several resonators in a dielectric block (1). An electrically conductive cover (10) is provided adjacent the top surface (3) of the dielectric block. The cover has a respective cut-out tab portion (7₁-7₇) located over each of the resonator holes (6₁-6₇) whereby the individual tabs may be bent to adjust the resonant frequency of the associated resonator. Alternatively, the coupling between resonators may be adjusted if the bendable tabs (11₁-11₇) are located between adjacent resonators. A cover (9) with bendable tabs, may also be disposed adjacent a side face (5) of the dielectric block, the tabs (12₁-12₇) being provided between resonators whereby the inter-resonant coupling may be adjusted.






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