Abstract-A new variety of millimeter-wave Fresnel-zone plate lens with enhanced focusing quality is described. Each full-wave zone of the lens is divided into four quarter-wave subzones, which are covered by dielectric rings having equal thickness but different permittivities. More practical equations are derived for the radii of the zones, and for the thickness of the lens by taking into account the angle of incidence of the electromagnetic wave.A Fresnel-zone plate antenna (FZPA) consisting of a quarterwave lens and a scalar feed is developed and analysed theoretically. Equations for the aperture field and far field are derived using multiple ray tracing through dielectric plates and vectorial Kirchhoff diffraction theory, respectively. It is demonstrated that the proposed transmissive-type FZPA has an aperture efficiency of more than 50% in the 60 GHz frequency band. This computed efficiency agree with the measured overall efficiency reported by other researchers for an X-band quarter-wave reflector-type FZPA.

The prediction of wall losses is a fundamental aspect in the planning of cellular systems. The broad variety of building materials and construction codes makes accurate attenuation prediction very difficult without the support of specific construction data or measurements. In this paper, the attenuation and equivalent electric parameters and of brick and doubly reinforced concrete walls are estimated for the 900-MHz band by fitting simple ray tracing models to empirical transmission data. The measurement setup is described, and extensive experimental results justifying the quasioptical modeling are presented.

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