Dual frequency band antenna combined with a high impedance band gap surface

A compact dual-band antenna structure for automotive and aerospace applications is discussed. A bow tie dual-band electromagnetic band gap (EBG) element geometry is presented that has a reduced cell dimension compared to the wavelength yet has sufficient bandwidth for mobile communication applications. The EBG was combined with a printed planar monopole to produce a structure 8 mm thick. The return loss and radiation patterns gave satisfactory performance at two frequency bands with bandwidths of 11% at 1700 MHz and 7% at 2600 MHz. There was suppression of the back radiation at both bands of 5 dB or better even for the small 3 times 3 element EBG used and the antenna was platform tolerant.     

Wideband reduced size electromagnetic bandgap structure

A novel electromagnetic bandgap element geometry is presented with compact dimensions and a wide bandwidth. The element has a small cell size of 22.8 mm and a measured bandwidth of 24% at 1.6 GHz. A useful second bandgap can be realised with a bandwidth of 6% at 2.5 GHz. Simulations show that using the same element dimensions on a higher dielectric constant substrate provides a bandgap at the lower 900 MHz GSM band with sufficient bandwidth.