Lk Products Oy

Jarmo Pyykko

Kimmo A Ervasti

The invention relates to a resonator coupling and a radio frequency filter, which comprise a transmission line resonator (106), preferably a helix resonator, having an upper and lower end, a transmission line (108, SL3) for coupling to the resonator, and a tap point (121), at which the transmission line (108, SL3) and the transmission line resonator (106) are in direct contact with each other, whereby the transmission line (106) is divided at the tap point (121) into a lower and upper part, the lower part comprising a first part (SL1) and the upper part comprising a second part (SL2). A coupling element (SL4) is placed at the tap point (121) in parallel with the transmission line resonator (106), coupled (M1) electromagnetically to the transmission line resonator (106), thus improving the stop/pass ratio of the filter. In addition, a second transmission line (SL5) can be arranged in parallel with the coupling element, coupled (M2) to said coupling element (SL4), whereby said coupling (M2) compensates for the resonating frequency change of the helix resonator with respect to the temperature.

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Oulu, Finland

Jarmo Pyykko