Radiation characteristics of a conical monopole antenna with a partially corrugated ground plane.

In order to preserve broadband performance, the conical monopole antenna is ideally mounted on a semi-infinite ground plane. Practical finite ground planes can introduce unwanted effects in the radiation patterns such as significant back lobes. Periodic surfaces such as rotationally symmetric corrugated structures have been proven capable of improving the radiation characteristics of a variety of antennas. In this paper, the radiation patterns of a conical antenna with a PEC reflector are initially presented. The PEC reflector is then replaced with a partially corrugated reflector surface. The effects of the partially corrugated reflector on the radiation patterns and electric field distribution along the reflector surface are investigated. The simulation results reveal that the radiation patterns of a conical antenna with a partially corrugated reflector are more stable over a wide frequency band than that for the PEC reflector

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 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

Radiation characteristics of a conical monopole antenna with a partially corrugated ground plane

In order to preserve broadband performance, the conical monopole antenna is ideally mounted on a semi-infinite ground plane. Practical finite ground planes can introduce unwanted effects in the radiation patterns such as significant back lobes. Periodic surfaces such as rotationally symmetric corrugated structures have been proven capable of improving the radiation characteristics of a variety of antennas. In this paper, the radiation patterns of a conical antenna with a PEC reflector are initially presented. The PEC reflector is then replaced with a partially corrugated reflector surface. The effects of the partially corrugated reflector on the radiation patterns and electric field distribution along the reflector surface are investigated. The simulation results reveal that the radiation patterns of a conical antenna with a partially corrugated reflector are more stable over a wide frequency band than that for the PEC reflector