Research on extremely low-profile wire antennas with electromagnetic band gap reflector

天线单元，每个电磁带隙（EBG）反射器，进行了分析，并揭示其辐射特性。天线高度被选择为非常小（小于0.07波长）。(1)螺旋元件：螺旋元件由具有0.05波长的天线高度的EBG反射器支撑。据证明，可以实现约83%的尺寸减小。(2)卷曲元件：卷曲天线由具有0.06波长的天线高度的EBG反射器支撑。据发现，卷曲可以匹配一个50欧姆的馈线与适当选择的宽度附近的天线输入的馈电导体。(3)倒置F元件：用EBG反射器制成两元件阵列，其中天线高度被选择为0.03波长。研究了同相和反相激励下的辐射特性。同相激励时驻波比带宽为10%，反相激励时驻波比带宽为21%。(4)折叠线元件：折叠线元件位于EBG反射器上方0.06波长处。结果表明，由于EBG反射器的存在，辐射电阻高于当一个完美的电导体背折叠线元件。(5)贴片元件：EBG反射器围绕圆偏振贴片。EBG反射器可以使交叉偏振分量小。研究了两种情况下的天线增益：一种情况下有导电引脚，另一种情况下没有导电引脚。

Antenna elements, each with an electromagnetic band gap(EBG) reflector, are analyzed and their radiation characteristics are revealed. The antenna height is chosen to be extremely small(less than 0.07 wavelength).(1) Spiral element : A spiral element is backed by an EBG reflector with an antenna height of 0.05 wavelength. It is demonstrated that an approximately 83% size reduction can be realized.(2) Curl element : A curl antenna is backed by an EBG reflector with an antenna height of 0.06 wavelength. It is found that the curl can match a 50-ohm feed line with an appropriately chosen width for the feed conductor near the antenna input.(3) Inverted F-element : A two-element array is made with an EBG reflector, where the antenna height is chosen to be 0.03 wavelength. The radiation characteristics for in-phase and opposite phase excitations are investigated. The bandwidth of VSWR is 10% for the in-phase excitation, and that for the opposite phase excitation is 21%.(4) Folded wire element : A folded wire element is located at 0.06 wavelength above an EBG reflector. It is revealed that the radiation resistance is higher, due to the presence of the EBG reflector, than that when a perfect electric conductor backs the folded wire element.(5) Patch element : An EBG reflector surrounds a circularly polarized patch. The EBG reflector can make the cross-polarization component small. The antenna gain is investigated for two cases : one case with conducing pins and the other without conducting pins.