US 7,352,326 B2 · Multiband planar antenna

Abstract

A multiband planar antenna intended for small-sized radio devices and a radio device. The basic structure of the antenna is a two-resonance P1FA, the radiating plane (320) of which has a structural part (321) corresponding to the lowest operating band and a structural part (322) corresponding to the upper operating band. In addition, a loop resonator (323) operating as a radiator is formed in the radiating plane. The ground conductor (325) of the feed line of the loop is at the same time the short-circuit conductor of the PIFA. The second conductor (326) of the feed line is connected to the opposite end of the loop, and it operates as the feed conductor of the PIFA. At the same time the structural part (321) of the radiating plane that corresponds to the lowest operating band is located between the loop and the structural part of the PIFA that corresponds to the upper operating band, in order to reduce interference between them. The resonance frequency of the loop radiator is arranged on the upper operating band of the antenna, for example. Thus the loop improves the matching of the antenna on the upper operating band and the matching and efficiency on the lowest operating band as well. This is based on additional inductance caused by the loop conductor (323) that functions as a part of the feed conductor of the PIFA.

Claims9

Dependent claims

A multiband planar antenna having at least a lowest operating band and a second operating band and comprising a ground plane (310, 410) and a radiating plane (320;

420;
520), which is at a feeding point (FP) connected to an antenna port of the radio device and at a short-circuit point (SP) to the ground plane, which radiating plane comprises a first conductor branch and a second part such that
the first conductor branch (321;
421;
521) together with the surrounding antenna parts forms a quarter-wave resonator shorted at the short-circuit point, a natural frequency of which resonator is located on the lowest operating band, and
the second part (322, 422, 525) together with the surrounding antenna parts forms a resonator, a natural frequency of which is located on the second operating band,
characterized in that the radiating plane further comprises a conductor loop (323, 423, 523) starting from the feeding point (FP), joining the rest of the radiating plane close to the short-circuit point and ending at the short-circuit point (SP) for forming a loop radiator and for improving antenna matching on the lowest operating band, and a part of the first conductor branch of the radiating plane is located between the conductor loop and said second part.

4 more elements

Dependencies are inferred from the claim text.

Multiband planar antenna

Life of this patent

Multiband planar antenna

Life of this patent

Abstract

Claims9