Electromagnetic Band-Gap Structures
Electromagnetic band-gap structures (EBGs) have many important properties for antenna technology. Our interest is in developing novel structures that provide high impedance surfaces particularly at lower frequencies such as the mobile telephone bands around 900MHz and upwards. This allows the development of more compact antennas that can operate close to metal surfaces or the human body. The research work focuses on finding new element geometries that are both small in terms of a wavelength and also providing either wideband or multi-band capabilities. Two EBG elements are shown here.
Above, a convoluted element developed with the University of Kent that provides a substantial reduction in the size of the element that measures just 0.1λ across.The bow tie based element below, is not quite as small as the convoluted element but has a wide bandwidth of 11%.
The frequency response of a related EBG element is also shown below. Further multi-band equivalents are being developed and incorporate compact antenna radiators.