H.D. Hristov (Chile)
Focusing, Lens, FZP lens, FZP lens antenna
This paper describes a microwave Fresnel zone plate (FZP) lens and antenna that can work also at multiple terahertz (THz) frequencies. Binary FZP antennas have been designed and analysed numerically based on the vector diffraction theory. The half-wave FZP has a comb-like focusing response at frequency harmonics proportional to the odd numerical sequence 1, 3, 5, … For example, a FZP lens antenna designed at the microwave frequency 1f f1=90 GHz can radiates according to the above sequence at the terahertz harmonic frequencies f3 =270 GHz, f5 =450 GHz, and so on. It is found that all harmonic gain peaks are identical in shape, bandwidth and top values. It is revealed that at any harmonic frequency the FZP antenna beam width closely follows the Rayleigh resolution criterion. It is clarified that if the antenna resolution is of primary importance and the high efficiency is not a vital constraint, the microwave FZP lens antenna can be a realistic terahertz antenna as well. Unique and expensive micro technology is not required to produce the simple and regular in size FZP microwave lenses. .Terahertz applications include spatial and frequency resolution (or filtering) devices and systems for metrology, imaging tomography for medical and security use, spectral analysis, and radio astronomy among others.
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