Lk Products Oy

Seppo Yrjola

Kimmo Koskiniemi

Panu Hagstrom

A harmonic filter is added to a radio frequency filter comprising at least one transmission line resonator (R1; R2; R3) to filter harmonic multiples of the filter's operating frequency. Coupling to the harmonic filter occurs through matching couplings and transmission lines (7; L1 to L9; L20; L28) in the filter or via the electromagnetic field of said transmission line resonator (R1; R2; R3). The harmonic filter advantageously comprises striplines (L13 to L19; L21 to L27; L29 to L49) manufactured in conjunction with the other stripline structures in the filter.

Integrated filter construction

The invention relates to a radiofrequency filter in which the coupling between the transmission line resonators is effected by using both a slot coupling and a link coupling. The coupling slot and the coupling link are designed so that changes of the coupling intensity in the link coupling caused by shifting of the resonator element is of the same size and of the opposite sign as a corresponding change in the slot coupling, whereby the changes compensate one another. The design is based on the fact that the distance of the coupling link from the resonator is longer close to the coupling slot than far away from the coupling slot.

Transmission line resonator filter with variable slot coupling and link

The present invention relates to an arrangement for separating transmission and reception accomplished through one and same antenna (A) in a transceiver, said arrangement comprising a filter and a switching element (K) and being provided with a common port to be coupled to the antenna (A), a transmitter branch (TX) port (T) to be coupled to the transmitter of the transceiver and a receiver branch port (RX) port (R) to be coupled to the receiver of the transceiver, and in which, as a response to a control signal, the switching element couples operationally to the common port alternatively the transmitter branch port (T) and the receiver branch port (R). The arrangement comprises a filter (S.sub.T,S.sub.F,S.sub.1,S.sub.2) including transmission line resonators, said filter being provided with adaptation couplings to be coupled to the transmission line resonators and for accomplishing couplings between the transmission line resonators. The adaptation couplings comprise an impedance adaptation circuit comprised of discrete components for adapting the filter to the antenna. The switching element (K, K.sub.T, K.sub.F) includes parts of the adaptation couplings of the filter, whereby the switching element is connected to the filter utilizing the adaptation couplings thereof and said impedance adaptation circuit is arranged in the switching element to serve as a phase shifter.

Arrangement for separating transmission and reception

A filter (1) for filtering certain frequencies of an electric signal. The filter (1) comprises components (HX1-HX4) for forming the frequency response of the filter, and components (A,C) for accomplishing coupling and impedance matching. The filter is provided with a directional coupler (10) composed of two transmission lines (A,B), one of them being a coupling line (A) or an impedance matching line.

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Oulu, Finland

Seppo Yrjola