Abstract: An adjustable monopole antenna especially intended for the mobile terminals. The adjusting circuit (930) of the antenna is located between the radiator (920) and the antenna port of a radio device and forms, together with the antenna feed conductor (901), a feed circuit. This circuit comprises an adjustable reactance between the feed conductor and the ground in series with the feed conductor or in both of those places. For example, the feed conductor can be connected by a multi-way switch to one of alternative transmission lines, which are typically short-circuited or open at their tail end and shorter than the quarter wave, each line acting for a certain reactance. The antenna operating band covers at a time only a part of the frequency range used by one or two radio systems, in which case the antenna matching is easier to arrange than of a real broadband antenna. The space required for both the radiator and the adjusting circuit is relatively small.

Abstract: The invention relates in one aspect to antenna useful with for example a flat a radio device. In one embodiment, the antenna comprises and internal monopole antenna that has an arrangement for improving its characteristics, including a planar monopole radiator and an auxiliary element. The auxiliary element can be a mere conductor strip, or a ceramic plate partly coated with a conductor for example. The conductor of the auxiliary element is connected to the ground at a point (SP), which is relatively close to the feed point (FP) of the planar element. The planar element can be shaped to form two operating bands for the antenna. The auxiliary element can be used to increase the bandwidth of the internal monopole antenna and/or to improve the omnidirectional radiation of the antenna.

Abstract: An adjustable monopole antenna especially intended for the mobile terminals. The adjusting circuit (930) of the antenna is located between the radiator (920) and the antenna port of a radio device and forms, together with the antenna feed conductor (901), a feed circuit. This circuit comprises an adjustable reactance between the feed conductor and the ground in series with the feed conductor or in both of those places. For example, the feed conductor can be connected by a multi-way switch to one of alternative transmission lines, which are typically short-circuited or open at their tail end and shorter than the quarter wave, each line acting for a certain reactance. The antenna operating band covers at a time only a part of the frequency range used by one or two radio systems, in which case the antenna matching is easier to arrange than of a real broadband antenna. The space required for both the radiator and the adjusting circuit is relatively small.