Measurement techniques for polar electromagnetic bandgap structures using an air spaced microstrip line

The ability to accurately pinpoint with a high degree of accuracy the occurrence of the stop-band property in the newly engineered EBG materials is fundamental to their establishment. Measurement methods capable of achieving this have been proposed in literature but require intricate adjustments to suit particular requirements. In this paper we report on a repeatable measurement technique for characterising the bandgap properties of EBG structures using an air spaced microstrip line. The device constructed is simple, economical, robust and capable of quantifying the properties of a wide range of EBG materials. A tapered microstrip line transition is used to match a 50 Omega coaxial port. Simulation and measurement results using a Polar-EBG are presented to show the versatility of the proposed technique. In addition to this we demonstrate that by changing the orientation of the surface under test (SUT), transverse electric surface wave measurements can be carried out. This apparatus and measurement technique is particularly applicable to fabric based EBG materials where measurements are especially challenging.