Abstract: A multiband antenna, and component for implementing a multiband antenna for, e.g., a small-sized radio device. In one embodiment, the antenna component comprises a simple and reliable dielectric substrate, the conductive coating of which forms a radiating element. This has a plurality (e.g., two) resonances for forming separate operating bands. The lower resonance is based on the entire element, and the upper resonance on the head part of the element. The conductive coating has a pattern, which functions as a parallel resonance circuit between the head part and the tail part of the element. The natural frequency of this parallel resonance circuit is in the range of the upper operating band of the antenna. The resonance frequencies of the antenna and thus its operating bands can be tuned independently of each other so that the tuning cycle need not be repeated.

Abstract: An arrangement for enhancing electrical isolation between antennas in antenna structures comprising at least two antennas, and a radio device applying the arrangement. The interfering antenna comprises components causing substantial degradation in radiation characteristics in the operating band of another antenna. For example, a PIFA (310) may comprise, instead of a short-circuit conductor, a conductive structure (312, 313, 314) having a parallel resonance in the operating band of another antenna (320). Mutual interference of radio parts using separate antennas can be made relatively small without electrical isolation arrangements between antenna elements. Moreover, the invention makes antenna filter design easier and reduces disadvantages caused by antenna filters.

Abstract: An arrangement for enhancing electrical isolation between antennas in antenna structures comprising at least two antennas, and a radio device applying the arrangement. The interfering antenna comprises components causing substantial degradation in radiation characteristics in the operating band of another antenna. For example, a PIFA (310) may comprise, instead of a short-circuit conductor, a conductive structure (312, 313, 314) having a parallel resonance in the operating band of another antenna (320). Mutual interference of radio parts using separate antennas can be made relatively small without electrical isolation arrangements between antenna elements. Moreover, the invention makes antenna filter design easier and reduces disadvantages caused by antenna filters.

Abstract: 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.

Abstract: 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.