Dual antenna

Abstract

A dielectric dual antenna intended especially for small-sized radio devices, by one partial antenna of which is implemented the lower operating band of the antenna and by the other partial antenna the upper operating band. The partial antennas have a shared substrate (440), which together with the radiators constitutes an integrated antenna component (400). The partial antennas also have a shared feed point (FP), the part of the antenna component to one direction from the plane, which leads through the feed point and is perpendicular to the upper surface of the substrate, belonging to one partial antenna and the part of the antenna component to the opposite direction belonging to the other partial antenna. At least one of the partial antennas comprises two radiators, the first one (411) of which joins the feed point and the second one (412) is connected to the ground (GND) from its outer end as viewed from the first radiator. This first radiator (411) and the radiator (421) of the other partial antenna, which joins the shared feed point, form a unitary common element (430) on the substrate surface. This common element is shortcircuited to the ground from at least one point (SP1, SP2) relatively near to the feed point. The matching of the dual antenna can be improved in either operating band without degrading it in the other operating band at the same time.

Description

technical field [0001] The present invention relates to an antenna structure for a small radio device comprising two electrically oppositely separated parts to realize two operating frequency bands. Background technique [0002] In small portable radio devices such as mobile phones, it is preferable to place the antenna within the housing of the device for ease of use. Furthermore, the design of the antenna is demanding as it tries to occupy as little space as possible. Additional design difficulties arise if the radio has to operate in several frequency ranges, the more difficult the wider these frequency ranges are. [0003] Internal antennas are mostly planar structures, in which case they comprise a radiating surface and a ground plane at a certain distance from the radiating surface. Planar antennas can be made smaller by making the radiating surface on the surface of a dielectric substrate instead of insulating it from air. The higher the dielectric constant of a ma...

AI Technical Summary

Problems solved by technology

[0012] The drawback of the above dual antenna solution is that the matching of the antennas in both the lower and upper operating frequency bands needs to be arranged, which increases the manufacturing cost and still does not achieve the desired result

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