Low-Radar Cross Section antennas attract substantial attention in Stealth Technology. The Radar Cross Section reduction performance of the microstrip antennas should be improved since they contribute to the overall Radar Cross Section. A novel microstrip patch antenna with a polarization converter metasurface is proposed to extend the Radar Cross Section (RCS) reduction bandwidth. The metasurface uses metallic strip structures to obtain the required polarization conversion for Radar Cross Section reduction. The proposed patch antenna shows the overall RCS reduction bandwidth of 7.25 GHz-24.83 GHz (110%) as compared to the metal sheet and the Reference Patch antenna. 10 dB RCS reduction is obtained from 8.33 GHz-9.16 GHz (9.49%) and from 12.81 GHz-18.85 GHz (38.16%) as compared with the Reference Patch antenna. The RCS reduction of the antenna and the antenna radiation patterns are verified by numerical simulations and experimental observations. The main novelty of the proposed design is its wideband RCS reduction for Transverse Electric as well as Transverse Magnetic polarization with enhancement in antenna radiation pattern parameters. Significant RCS reduction can also be obtained for oblique incidence.
With the supersonic growth of mobile data demand, the fifth generation (5G) mobile network would exploit the extensive amount of spectrum in the millimeter-wave (mm-Wave) bands to tremendously increase communication capacity. There are conceptual differences between mm-Wave communications and other existing communication systems, in terms of high propagation loss, directivity, and sensitivity to blockage. These characteristics of mm-Wave communications present several challenges to completely exploit the potential of mm-Wave communications, including integrated circuits and system design, interference management, spatial reuse, anti-blockage, and dynamics control. 5G mobile communication systems with sub-6 GHz and millimeter-wave bands are already replacing 4G and 4.5G systems as an evolution towards higher-speed mobile communication and wider bandwidth. From the hardware perspective, the 5G-band causes the miniaturization of RF components including the antennas. In this article, an overview of recent research is presented that discusses design challenges and measurement considerations for various types of compact 5G antennas.
Compact antenna with good performance characteristics is always preferred for small IoT (Internet of Things) sensor nodes. The novelty of this proposed work is not in terms of design but in terms of application as Log-Periodic antennas has been so far used for UHF/VHF (Ultra High Frequency/Very High Frequency) and TV reception applications, and in this paper, the advantages of Log-Periodic structure have been exploited for IoT applications. This antenna design consists of two Log-Periodic like structured radiating elements on an FR4 substrate of 1.6\,mm thickness. The compact antenna of size of 15 mm×17 mm covers a bandwidth ranging from 2.01 GHz to 4.04 GHz including the WiMAX (2.3 GHz-2.4 GHz, 2.5 GHz-2.7 GHz and 3.4 GHz-3.6 GHz) and WLAN (2.4 GHz and 3.6 GHz) frequency bands. This system employs Defected Ground Structure (DGS) technique to obtain the required range of bandwidth of operation, for improving the isolation and obtaining mutual coupling suppression between the two individual elements. This miniaturized cheap antenna has a very low ECC (Envelope Correlation Coefficient) value and all other MIMO (Multiple Input Multiple Output) parameters in acceptable range. The isolation obtained over the entire range of operation is below -30 dB, and the performance efficiency is as good as 92.8% with a maximum gain of 2.9 dB. The simulated and measured results of the antenna system are also found to be in good agreement. The MIMO system can be considered as a good candidate for medium range IoT applications for its small size and good performance.
This paper reports a novel, cost effective, and compact ultra-wideband (UWB) antenna for applications in an unlicensed-frequency band of 3.1-10.6 GHz. To achieve the UWB operation, a novel concept of annular shapes, circular slot combinations, and partial ground is employed. Furthermore, the proposed antenna with novel configuration occupies an attractive size of only 18×12 mm2 which allows compatibility with portable UWB application devices. This flower-horn shaped UWB antenna is printed on a cost-effective FR-4 substrate, which exhibits a dielectric-constant of 4.4 and a loss-tangent of 0.019. The fabricated prototype is experimentally tested, and measured results validate the design approach of presented UWB antenna. The measured results confirm its UWB characteristics covering 3.1-11.2 GHz with S11 ≤ -10 dB. Also, a maximum peak-gain of 5.05 dBi at 9 GHz and a minimum radiation-efficiency of 94.35% are noted in the full operating-band. A good agreement has been obtained between the simulated and measured results in terms of reflection-coefficient, gain, radiation-efficiency, radiation patterns and group delay which confirm the suitability of suggested small printed antenna for the intended UWB applications.