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A new sine-wall slot array antenna is proposed by using the space-tapered technique to decrease both sidelobe level (SLL) and second-order lobe level (SOLL), simultaneously. In the proposed method, the genetic optimization algorithm is utilized to implement the space-tapered technique and achieve the slots center positions. Then, the waveguide side walls are rippled by sine-form segments to achieve uniform slots excitation needed in the space-tapered technique. Finally, a seven-slot array is designed and fabricated at 9.375 GHz to demonstrate the proposed idea. The proposed slot array achieves 14 dB gain and about 7.5 dB lower SLL as well as 7 dB lower SOLL and compared with the well-known Elliott’s design procedure. [ABSTRACT FROM PUBLISHER]

A novel compact monopulse cavity-backed substrate integrated waveguide (SIW) antenna is proposed. The antenna consists of an array of four circularly polarized (CP) cavity-backed SIW antennas, three dual-mode hybrid coupler, and three input ports. \mathrmTE{10} and \mathrmTE{20} modes are excited in the dual-mode hybrid to produce sum and difference patterns, respectively. The antenna is modeled with a fast full-wave hybrid numerical method and also simulated using full-wave Ansoft HFSS. The whole antenna is integrated on a two-layer dielectric with the size of 42\;\mathrmmm \times 36\;\mathrmmm. A prototype of the proposed monopulse antenna at the center frequency of 9.9 GHz is manufactured. Measured results show - 10\-\mathrmdB impedance bandwidth of 2.4%, 3-dB axial ratio (AR) bandwidth of 1.75%, 12.3-dBi gain, and - 28\-\mathrmdB null depth. The proposed antenna has good monopulse radiation characteristics, high efficiency, and can be easily integrated with planar circuits. [ABSTRACT FROM PUBLISHER]

The Angular Z-Buffer (AZB) algorithm is widely used to speed up the ray tracing. Although the basic idea of this approach is definitely true, there is an error in the implementation method presented by developers of AZB. Here in this communication, the error is noted and, using a mathematical solution, an efficient remedy is put forward and implemented. Moreover, it is shown, by simulation of an appropriate three-dimensional case study using the original AZB and modified AZB, that a loss of accuracy occurs in the electrical field distribution predicted by the original. [ABSTRACT FROM AUTHOR]

An efficient propagation prediction model is presented. The modeling is subdivided into three phases; preprocessing, tracing rays, and postprocessing. Information obtained from the relations between the facet pairs is employed in the preprocessing. Heuristic removal of double tracing of rays shared among adjacent tubes halves the tube tracing time. For the prediction of the E-field over a surface, an accurate geometrical approach is proposed and a backtracking calculation method is tailored. Also, the multiple counting shortcoming is resolved in SBR and, single and double diffraction are modeled. The method directly functions on three dimensional geometry of the problem and considers all chains of interactions up to the second order successive diffractions. Finally, the applicability and reliability of the method is verified by comparison of results with a numerical method and measurements. [ABSTRACT FROM PUBLISHER]