Minimum $Q$ Electrically Small Antennas
Minimum $Q$ Electrically Small Antennas
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最低 $Q$ 电气小天线
DOI：
10.1109/tap.2012.2201096
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发表时间：
2012
影响因子：
5.7
通讯作者：
O. Kim
中科院分区：
文献类型：
--
作者：
O. Kim
理论上，在完全抑制天线球体中储能的前提下，将TM1m和TE1m两种球模相结合，可以使球形电小天线的孤立谐振辐射品质因数Q达到最小。利用矢量球面波理论得到的储能的闭合表达式，证明了磁涂层金属芯同时降低了TM1M模和TE1M模的内部储能，从而形成了Q值接近基本极小值的自谐振天线。多臂球面螺旋天线的数值计算结果证实了理论预测。例如，具有磁涂覆理想导电磁芯的四臂球形螺旋天线(ka=0.254)的Q值是Chu下限的0.66倍，或者是最小Q值的1.25倍。
Theoretically, the minimum radiation quality factor Q of an isolated resonance can be achieved in a spherical electrically small antenna by combining TM1m and TE1m spherical modes, provided that the stored energy in the antenna spherical volume is totally suppressed. Using closed-form expressions for the stored energies obtained through the vector spherical wave theory, it is shown that a magnetic-coated metal core reduces the internal stored energy of both TM1m and TE1m modes simultaneously, so that a self-resonant antenna with the Q approaching the fundamental minimum is created. Numerical results for a multiarm spherical helix antenna confirm the theoretical predictions. For example, a 4-arm spherical helix antenna with a magnetic-coated perfectly electrically conducting core (ka=0.254) exhibits the Q of 0.66 times the Chu lower bound, or 1.25 times the minimum Q.