In this article, two novel kinds of focusing elements as reflectors are analyzed and compared. One is the grooved Fresnel zone plate reflector with continuous phase-correcting. The other called subzone paraboloid reflector, has the profile that consists of a series of paraboloids. Their diffraction efficiencies and bandwidths are described. The two elements still preserve the advantages of Fresnel zone plates, namely, low profile, high efficiency, and simple fabrication. Two dual-reflector antennas using the proposed focusing elements as the main reflectors are simulated and the results show that these antennas have good radiation performances. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:101-108, 2015.

The analysis and comparison of two novel kinds of focusing elements as reflectors

We presented a design of the zone plate with continuous phase with Polytetrafluoroethylene (PTFE) based on scalar
diffraction theory. Diffraction fields of the zone plate with continuous phase and the phase-correcting Fresnel zone plate
with incidence of uniform plane wave were analyzed and compared. The effects of the focal length and diameter of the
zone plate with continuous phase on the diffraction field were discussed. The simulations of intensity distribution on the
focal plane and the optic axis based on Rayleigh-Sommerfeld diffraction formula were completed using Matlab. The
results indicate that the zone plate with continuous phase performs better than the phase-correcting Fresnel zone plate.
The intensity on the focus of the zone plate with continuous phase is 1.17, 1.35, 2.62 times stronger than that on 8-level,
4-level, 2-level phase-correcting Fresnel zone plate's respectively. The fabrication process might give rise to a phase
error, such as groove depth error, surface roughness. The effects of the phase errors on the performance of the zone plate
were discussed.

Tao Jin

Papers

Diffractive efficiency of terahertz zone plates with continuous phase