The Prototype of a Wideband Ku-Band Conical Corrugated Horn Antenna with 3-D Printing Technology

This study is about the design and production of a conical corrugated horn antenna used to feed reflector antennas in satellite communication (direct broadcast satellite-DBS) systems. The antenna designed with CST Microwave Studio program operates within wideband of 10.5-18.5 GHz at Ku-band. The prototype is realized with new generation 3D printing technology and conductive paint coating method, which makes the antenna lightweight and provides low cost and faster production. According to measurement results, the antenna has return loss almost better than 20 dB, gain value of minimum 14.5 dBi and sidelobe level of -18 dB at most within 1.76:1 frequency bandwidth. Antenna is observed to have a gain loss of at most 1.5-2 dB within the band as compared to the same antenna with high conductivity metal, which needs higher cost and production time for the manufacturing

Base Station Antenna with Enhanced Cross Polarization Discrimination Performance by Using Horizontal Meandered Dipole and Vertical Parasitic Elements

This study is related with the design of a ± 45° dual polarized base station antenna with improved cross-polarization discrimination (XPD) values. Parasitic elements are added to antenna design formed by orthogonal two compact meandered dipole above ground plane. The antenna designed with CST Microwave Studio program has VSWR ≤ 2 within 1.71-2.69 GHz frequency band, which covers GSM 1800/3G/LTE bands. The antenna has minimum of 0 dBi gain in the beamwidth of 120° ( 60°) at azimuth plane (ϕ = 0°) along the band, and XPD values being minimum of 2 dB at 1.71-2.4 GHz for  60° without parasitic elements are improved to 10 dB with parasitic elements. This design initially had two horizontal straight monopoles on the ground plane perpendicular to each other. Afterwards, antenna with microstrip balun feed applied but the XPD values were not appropriate to expected results. Because of that, by using image theory, vertical parasitic elements were added to get appropriate XPD values. Later, meandered structure used to make antenna smaller. Finally, according to base station applications, antenna frequencies optimized to 1.71 GHz and 2.69 GHz. The designed and optimized antenna produced and measured in laboratory environment. Return losses for port 1 and port 2 are measured above the 10 dB and isolation between the port 1 and port 2 are measured above the 20 dB. In addition, the maximum gain values are measured between 3 dB and 7 dB in 1.71 GHz and 2.69 GHz frequency band.  Finally, XPD values are measured more than 10 dB in bandwidth

An Electromagnetic Target Classification Method for the Target Sets with Alien Target: Application to Small-scale Aircraft Targets

The electromagnetic target classification is a challenging problem since the scattered field from a target is highly dependent on operating frequency, polarization and aspect angle. In order to minimize adverse effects of these dependencies an intelligent classifier containing some distinguishable target features is needed. In addition, in order to be suitable for real target applications, the properties of operating with moderate frequency bandwidth and discriminating an alien target from a target set containing friend targets are important. In this study, an electromagnetic target classification method for isolated targets using noisy data in the classifier design to obtain high accuracy performance in a wider SNR range and having the ability of discrimination of an alien target without any priori information is introduced. The proposed method is mainly based on a late-time resonance region target classification technique, which was reported recently to use the multiple signal classification (MUSIC) algorithm and natural-resonance mechanism modeled by singularity expansion method (SEM) for target feature extraction, and modified for target sets containing alien target(s). The proposed classifier design method is demonstrated and tested for a target set of five friend and one alien small-scale aircraft targets. According to the test result, the proposed method gives high accuracy rates for this target set

A DUAL-POLARIZED WIDE-BAND PATCH ANTENNA FOR INDOOR MOBILE COMMUNICATION APPLICATIONS

This paper proposes the configuration of a dual polarized wide-band patch antenna system suitable for indoor mobile communication applications. This configuration consists of two patch antennas, which have different feed structures from classical patch antenna configuration. These antennas, which are separated by a thin absorber to have a good isolation, are fed independently to obtain dual polarization. The antenna structure is designed, simulated, manufactured and measured. The operation bandwidth spans 1900-2700 MHz covering Bluetooth, Wireless Local Area Networks (WLAN) and Universal Mobile Telecommunications System (UMTS) bands. The simulations show good agreement with the measurement results that the antennas have return losses higher than 15 dB, and the coupling between two antennas is below -20 dB within the operation band

E-plane sectoral horn power divider

E-plane sectoral horn power divider design method for high-power antenna array applications is presented. In this method, power division is proportional to the cross section areas of the waveguide channels at the aperture of an E-plane sectoral horn antenna. Two different power dividers are designed and produced to be used with an X-band antenna array having 30 dB Taylor distribution. The first one employs a simple E-plane sectoral horn antenna. This straightforward application of the method might be limited with production tolerances. The second one incorporates a corrugated E-plane sectoral horn antenna, whose design is relatively complex but less sensitive to production tolerances. The produced dividers are compared based on simulations and measurements and good agreement with the theoretical expectations is observed for both types

Dual-polarised T/R antenna system suitable for FMCW altimeter radar applications

The authors propose a dual-polarised T/R antenna system that utilises a 3 dB 90 degrees hybrid coupler and a dual-polarised antenna. From the practical point of view the T/R isolation performance of this system can be made better than that of systems using circulators. There is no power loss both in transmit and receive modes compared to 6 dB total loss in a conventional system using a hybrid coupler and a single polarised antenna. To validate the system performance, a sample structure is realised for a C band application. The presented system analysis and measurements are for an above-ground application. The measurements show good agreement with the theoretical expectations

Accuracy of the equivalent noise model of clutter in radar equation

Practical approaches to evaluate the performance of a radar using the radar range equation are valuable as they provide very quick assessment of the chosen radar parameters. Barton proposed the concept of equivalent noise power for clutter which is added to the thermal noise in the radar range equation. This paper is aimed at evaluating the accuracy of this approach by applying the concept to the detection of various Swerling targets in sea clutter. Barton's method will be compared with Watts rigorous approach