Tunable multiband antenna with passive and active circuitry

摘要

An electronic device may have an antenna for providing coverage in wireless communications bands of interest such as a low frequency communications band and a high frequency communications band. The antenna may have an antenna ground and an antenna resonating element. The antenna resonating element may have a high band arm that contributes to a first high band resonance in the high band and may have a low band arm that exhibits a low band resonance in the low band. A passive filter that is coupled between first and second portions of the antenna resonating element may be configured to exhibit a short circuit impedance associated with a bypass path that allows the antenna resonating element to contribute to a second high band resonance in the high band.

主权项

1. An antenna, comprising:
an inverted-F antenna resonating element having a low band arm and a high band arm, wherein the high band arm has a bend and the low band arm has first, second, and third portions, the first portion extends parallel to the second portion, and the third portion extends between the first and second portions and perpendicular to the first and second portions;
an antenna ground, wherein the low band arm and the antenna ground are configured to resonate in a low communications band and the high band arm and the antenna ground are configured to resonate in a first high communications band;an antenna feed having a first feed terminal coupled to the inverted-F antenna resonating element and a second feed terminal coupled to the antenna ground;a short circuit path coupled between the inverted-F antenna resonating element and the antenna ground, wherein the first portion of the low band arm and the high band arm extend from opposing sides of the short circuit path;a filter coupled between the first portion of the low band arm and the second portion of the low band arm, wherein the filter is configured to form a short circuit between the first and second portions of the low band arm in a second high communications band, the short circuit forms a path length that is shorter than the low band arm, and the filter is configured to form an open circuit in the low communications band; anda tunable component coupled between the second portion of the low band arm and the antenna ground, wherein the tunable component is configured tune the low communications band at which the low band arm and the antenna ground resonate.