Multi-band compact tunable directional antenna for wireless communication devices

摘要

An antenna for wireless communication devices provides resonance over at least two frequency bands with a directional radiation pattern and reduced specific absorption rate (SAR). The antenna structure includes of a formed conducting plate resonator spaced from a larger substantially rectangular ground plane conductor. The antenna structure can be located near one end of ground plane conductor. Single feed and ground connections are provided on adjacent edges of the resonator. Two or more tuning capacitors cause the resonator to resonate over two or more frequency ranges. Tuning of the higher frequency band may be done without affecting the lower frequency band in the case of a dual band version. The sizes and shape of the resonator and ground plane are compatible with the dimensions of wireless communications devices such as cell phones. The resonator may be conveniently installed internally at the top rear of a wireless communications device, providing substantial front to back ratio in the antenna radiation pattern, reducing the specific absorption rate (SAR) for devices, such as cell phones positioned close to a user's head or body when in use.