Variable permittivity dielectric material loaded stepped-horn antenna

CHAPTER 5CONCLUSIONS AND FUTURE WORKStepped-horn antenna with variable permittivity dielectric material loading is proposed andanalyzed using hybrid numerical method. In the analysis, tapered region including steppedwaveguide section is divided into a number of rectangular waveguide sections filled withthe lossless dielectric material. Following the standard mode matching, a set of generalizedscattering matrix equations in each junction are obtained. The overall scattering matrixof the horn is evaluated by cascading the scattering matrices of individual steps. Thegeneralized reflection matrix of the aperture is determined using the method of moments.Then the generalized scattering matrix of the horn is combined with reflection matrix ofthe aperture. This analysis extended to determine yields the complex weighting coefficientof each mode at the horn aperture in terms of the power of the incident TE10 mode.Finally, the results are used to determine the input reflection coefficient of the antennaincluding the radiation patterns. Different dielectric materials are applied to achieve betterperformance characteristics. It was observed that the dielectric material loading improvesgain characteristics. Due to the optimization of stepped-horn antennas, aperture efficiency,cross-polarization and gain characteristics were improved. Dielectric material loading tostepped-horn antenna reduced of physical dimensions of the antenna and also improvedgain level. It is observed that for higher dielectric constant material and larger apertures,higher TEm0 modes are needed to be included into the optimization. However, undesiredmodes would also be excited at the aperture. For future work, multi-stepped horn antennaloaded with dielectric materials has to be investigated to excite the higher order TE m0modes and to cancel the undesired modes at the aperture.80