Current Issue : April - June Volume : 2018 Issue Number : 2 Articles : 5 Articles
This paper presents low-profile broadband antennas, which are composed of four parasitic patches placed between planar\nradiators and a perfect electric conductor ground plane. Two types of planar radiators, a conventional dipole and a crossed\ndipole, are employed to produce linearly polarized (LP) and circularly polarized (CP) radiations, respectively. The radiator\nand parasitic patches are realized on thin substrates to lower the cost. Owing to the presence of parasitic patches, the antenna\nperformance improves in terms of profile reduction, resonant frequency decrease, and bandwidth enhancement. These\nimprovements are discussed and confirmed computationally and experimentally. The LP design with the overall dimensions of\n120mmÃ?â?? 120mmÃ?â?? 16.3mm (0.64Ã?»0 Ã?â?? 0.64Ã?»0 Ã?â?? 0.087Ã?»0 at 1.6 GHz) has a |S11| < âË?â??10 dB bandwidth of 1.465ââ?¬â??1.740 GHz (17.2%),\na broadside gain of 8.5ââ?¬â??8.8 dBi, and a radiation efficiency > 96%. The CP design, which has the same physical size as the LP case,\nhas a |S11| < âË?â??10 dB bandwidth of 1.388ââ?¬â??1.754 GHz (23.3%), a 3 dB AR (axial ratio) bandwidth of 1.450ââ?¬â??1.685 GHz (15.0%), a\nright-hand CP broadside gain of 7.8ââ?¬â??8.7 dBic, and a radiation efficiency > 90%....
A beam expanding radome for 76.5 GHz automotive radar antennas is presented whose inner surface is engraved with corrugations.\nThe radar used for blind spot detection (BSD) requires a very wide beam width to ensure longer time for tracking out-of-sight\nobjects. It is found that the corrugations modulate the phase velocities of the waves along the surface, which increases beam\nwidth in the far field. In addition, defects in the corrugation increase beam width even further. The presented structure satisfies\nthe beam width requirement while keeping a low profile....
This paper proposes a new method to the broadband RCS reduction with the artificial magnetic conductor (AMC) surfaces. The\nAMC surfaces can introduce a zero-degree reflection phase shift to incident waves. The phase difference between the antenna\nand AMC structures is 180�°. Therefore, the AMC structures can be used to achieve RCS reduction. However, the bandwidth of\nzero-degree reflection phase of AMC structures is very narrow. In light of this, a novel gradually concentric ring arrangement\nAMC (GCRA-AMC) which can be applied to achieve the broadband RCS reduction is presented. The simulated and measured\nresults show that the radiation performance of antennas is preserved when the GCRA-AMC is used. The RCS of the antenna\nwith GCRA-AMC has been considerably reduced in a broad frequency band. The largest RCS reduction is more than 17 dB....
An active skin antenna with structural load-bearing and electromagnetic functions is usually installed in the structural surface of\nmobile vehicles such as aircrafts, warships, and high-speed train. This paper presents the design, fabrication, and testing of a\nnovel active skin antenna which consists of an encapsulation shell, antenna skin, and RF and beam control circuits. The antenna\nskin which consists of the facesheet, honeycomb, array framework, and microstrip antenna elements was designed by using\nBayesian optimization, in order to improve the design efficiency. An active skin antenna prototype with 32 microstrip antenna\nelements was fabricated by using a hybrid manufacturing method. In this method, 3D printing technology was applied to\nfabricate the array framework, and the different layers were bonded to form the final antenna skin by using traditional\ncomposite process. Some experimental testing was conducted, and the testing results validate the feasibility the proposed\nantenna skin structure. The proposed design and fabrication technique is suitable for the development of conformal\nload-bearing antenna or smart skin antenna installed in the structural surface of aircraft, warships, and armored vehicles...
In this paper, we investigate a new printed antenna based on the 2D image of a fractal tree-leaf geometry by studying the effect of the\nirregular boundary of the proposed antenna on its radiation characteristics. Both the impedance matching properties and the\nradiation patterns of the antenna are studied over the frequency band 1ââ?¬â??6 GHz. Four configurations are designed by increasing\nthe complexity of the structure, which ranges from iteration 0 to iteration 3. The fractal properties of the proposed tree-leaf\nantenna are then compared to those of a conventional fractal antenna with smooth edges. Following this, the proposed antennas\nare fabricated and characterized experimentally. Finally, results are analyzed and discussed, and a practical application for this\nnew type of antennas is proposed...
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