Study on Optimization of Different Characteristics of Novel Shaped FSS
This paper deals with the simulated as well as measured results of a Frequency selective surface with perfectly conducting novel shaped elements. This frequency selective surface (FSS) acts like a single band-reject filter. The proposed design has been investigated theoretically using Ansoft Designer® software in which the reflection and transmission bands have been predicted by the method known as Method of Moment. Further experimental investigation is performed using standard microwave test bench. In comparison to the reference square patched Frequency Selective Surface (FSS) without slot, this FSS with novel design can provide size reduction up to 84.98%. Efforts have been given to achieve optimized value for different characteristics of FSS.
Design of a dichroic Cassegrain subreflector
The design of a dichroic subreflector for a dual-frequency reflector antenna is described. This antenna consists of a Ku -band Cassegrain feed requiring the subreflector surface to be highly reflective at 13-15 GHz and a primary focus S -band feed requiring the subreflector to be transparent at 2.0-2.3 GHz. Such a performance is achieved by a surface of crossed dipoles printed on a dielectric sheet. The influence of parameters, dipole length, width and spacing, and the dielectric constant and thickness of the sheet on the reflection and transmission coefficients is experimentally evaluated. An analysis based upon the Floquent mode theory is shown to correctly predict the experimental results. The construction of a hyperbolic subreflector using the selected surface parameters is briefly described. As compared to a solid subreflector of identical shape, this dichroic subreflector produced a negligible loss (less than 0.1 dB) over a 13-15 GHz band. At the S band the loss was less than 0.2 dB over narrow selected bands and the axial ratio deterioration was also no more than 0.2 dB.
A low-loss circularly polarized dichroic plate
Dichroic plate has orthogonally-disposed, loaded dipole apertures with their orientations arranged so as to cancel cross-coupling effects which would otherwise result in power loss to circularly polarized signal.