MINIATURISED LOW FREQUENCY ANTENNAS INTEGRATED WITH BAND GAP STRUCTURES

近年来，移动无线通信系统发展迅速，特别是移动电话和网络系统，从900 MHz增加到约6 GHz。这直接导致了技术的进步，如小型多频段天线的开发、紧凑型宽带组件以及频率选择表面(FSS)和相关电磁带隙(EBG)材料的应用。在低于这一频率的情况下，例如30兆赫的军事通信频段、110-200兆赫的树叶穿透雷达、100兆赫和200兆赫的广播频段、100-400兆赫的深空飞行任务和卫星紧急信标以及400兆赫的TETRA，取得的成果相对较少，主要是因为这些频率所涉及的物理尺寸很大。在这些低频下，往往使用类似单极子的天线，这代表着在空间和军事应用中特别关键的单一故障。这项应用的目的是设计小型化的低轮廓天线，并将它们集成在高阻抗EBG/FSS表面(HIS)上，用于长波长应用，提供独立于平台的天线安装。天线不仅很小，而且能够集成到许多车辆平台上，而不依赖于与车辆表面的相互作用。主要的挑战是开发物理上比波长小得多的天线和HIS结构，但在小型EBG阵列配置中应用却是有效的。为此，无源和有源集总电路元件元件将被结合到新型天线及其表面中，以减小其尺寸。将研究HIS元件的小阵列的性能，以改进其性能，特别是与小型化低频天线集成时的性能。

The growth in mobile wireless communication systems has been rapid in recent years particularly for mobile telephone and network systems from 900MHz to about 6GHz. This has directly led to advances in technology such as the development of small multi-band antennas, compact wideband components and the application of frequency selective surfaces (FSS) and related electromagnetic band gap (EBG) materials. At frequencies below this such as the military communication bands at 30MHz, foliage penetrating radar at 110-200MHz, broadcast bands at 100MHz and 200MHz, deep space missions and satellite emergency beacons 100-400 MHz and TETRA at 400MHz, relatively little has been achieved mainly due to the large physical size involved at these frequencies. At these low frequencies monopole like antennas tend to be used and these represent single fault failures that are particularly crucial in space and military applications. The purpose of this application is to design miniaturised low profile antennas and integrate them over high impedance EBG/FSS surfaces (HIS) for long wavelength applications providing a platform independent antenna installation. The antennas would not only be small but also able to be integrated onto many vehicular platforms independent of interactions with the vehicle surface. The main challenge is to develop antenna and HIS structures that are physically much smaller than the wavelength and yet effective in their application in small EBG array configurations. To this end both passive and active lumped circuit element components will be incorporated into novel antenna and HIS surfaces to reduce their size. The performance of small arrays of HIS elements will be studied to improve their performance particularly when integrated with miniaturised low frequency antennas.