一种感性耦合馈电的水平极化全向辐射环天线

An Inductively-coupled Fed Loop Antenna with a Horizontally Polarized Omnidirectional Radiation Pattern

设计了一种可用于2．4-GHzWLAN接入设备的感性耦合馈电的水平极化全向辐射环天线。该天线采用周期性加载的四个交指电容使得周长约为一个波长的辐射环上的电流均匀同相，从而得到全向水平极化的辐射特性。采用馈电小环对辐射环进行耦合馈电，使天线输入阻抗的调节更自由，易于与50Q馈线匹配。同时对感性耦合馈电进行了分析，给出了天线的设计思路。天线样品的测试结果表明该天线具有170MHz的带宽（2．365-2．535GHz），足够覆盖2．4-GHzWLAN频段。该天线具有结构紧凑、设计过程简单和易于工程实现等优点。

An inductively-coupled fed loop antenna with a horizontally polarized omnidirectional radiation pattern for 2.4-GHz WLAN access-point apphcations is proposed in this paper. Four periodically loaded in- terdigital capacitors allows currents on the radiating loop remain uniform and in phase, thus a horizontally po- larized omnidirectional radiation pattern in the far field is achieved, even though the perimeter of the radiating loop is about one operating wavelength. A feeding loop is utilized to inductively feed the radiating loop, which makes the tuning of the input impedance more flexible. Therefore the impedance matching to a 50 Ω feeding hne is very easy. The mechanism of inductive feed is analyzed and a brief design procedure of the antenna is also given. The measured bandwidth of the antenna is 170 MHz （2.365 GHz-2.535 GHz）, which is totally enough to cover 2.4-GHz WLAN band. The proposed antenna has the advantages of compact size, clear design proce- dure and easy fabrication.