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

分析了各天线单元的电磁带隙（EBG）反射器，揭示了它们的辐射特性。天线高度选择极小（小于0.07波长）。(1)螺旋元件：螺旋元件背后是一个天线高度为0.05波长的EBG反射器。结果表明，可以实现约83%的尺寸减小。(2)旋度元件：旋度天线背后有一个EBG反射器，天线高度为0.06波长。结果表明，旋度可以匹配天线输入附近馈电导体宽度适当的50欧姆馈电线。(3)倒f元：采用EBG反射器构成双元阵列，天线高度选择0.03波长。研究了同相激励和反相激励的辐射特性。同相激励的驻波比带宽为10%，同相激励的驻波比带宽为21%。(4)折线元件：折线元件位于EBG反射器上方0.06波长处。结果表明，由于EBG反射器的存在，其辐射电阻比在完美电导体的背面折叠导线元件时要高。(5)贴片元件：EBG反射器围绕圆偏振贴片。EBG反射器可以减小交叉偏振分量。研究了带导电引脚和不带导电引脚两种情况下的天线增益。

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.