This article describes a target simulator for FMCW radar sensors which, working on the frequency shift principle, deals with the presence of an unwanted (mirror) target. A simple method is proposed to suppress the mirror target by utilizing an IQ mixer in simulator circuitry which enables single-sideband modulation. Achievable combinations of speed and distance of simulated targets are also presented. In addition, the generation of targets closer than the physical distance of the simulator, a radar parameter estimation and a simulator calibration are included. All presented principles were verified by a laboratory experiment with a 24 GHz FMCW radar module and other commercially available components.
Directional Currents Method, which was developed and tested for rectangular horn antennas recently by Polat and Daşbaşı, is applied to derive explicit radiation fields of a conical horn antenna located over a simple lossy dielectric half-space. The influence of presence of transmission medium on E- and H-plane radiation performances of the conical horn is displayed under dominant mode excitation in comparison with similar results for a pyramidal horn in X-band. The accuracy of the radiation fields when the conical horn is located close to air-ocean interface is checked by comparing with the full wave simulation data of the commercial software CST TM .
Hertz-Heaviside Field Equations (HHFE) which describe radiation by arbitrary volumetric bodies in arbitrary motion are reviewed. The special case of HHFE for moving electric and magnetic Hertzian dipoles in arbitrary motion are investigated in the sense of Schwartz-Sobolev distributions. In presence of moving non-volumetric radiators HHFE decouple into wave equations expressed by D’Alembert wave operator of stationary media enhanced by convection currents with Diracdelta behavior. The electric and magnetic radiation fields of these dipole sources are discussed and their Doppler analyses are carried out for certain modes of motion.
This paper presents a comparison of millimeter-wave Luneburg lens antennas designed for an additive and subtractive manufacturing technologies. The proposed antennas are investigated in terms of technology and material limitations. An experimental characterization of the additively and subtractively manufactured Luneburg lens is carried out in W-band (75-110 GHz). The proposed lens antennas achieved realized gain of 18.18 dBi and 24.6 dBi at a frequency of 80 GHz, respectively. The right choice of the lenses building blocks and its material properties have significant effect on the overall antenna performance.
In this paper, dyadic Green's functions (DGFs) for a point source in the presence of a cylindrical isotropic metasurface with a circular cross-section are presented in closed form. The DGFs are constructed from cylindrical vector wave functions, and scattering coefficients are derived using the method of scattering superposition (SSP). It is assumed that the metasurface is electromagnetically thin. Therefore, the metasurface is suitably modeled using the generalized sheet transition conditions (GSTCs) method. By using the DGFs of this structure, the electric field due to an infinitesimal electric dipole oriented in the direction of cylindrical metasurface in the near- and far-field regions is obtained. Numerical results are compared with the results of a commercial software. The results are in good agreement with each other.
