Ahmet Serdar Turk

Partially Dielectric-Loaded Ridged Horn Antenna Design for Ultrawideband Gain and Radiation Performance Enhancement

In this letter, a partially dielectric-loaded double-ridged horn antenna (PD-DRHA) that operates at 1-18-GHz frequency band is proposed for ultrawideband applications. The partially dielectric loading technique using a small lens inward the aperture has been implemented to enhance the gain of the standard double-ridged horn antenna (DRHA), without changing the physical dimensions. Approximately 5 dB gain increment level is achieved from 5 to 15 GHz with slight changes on return loss characteristics. Moreover, the pattern distortion of DRHA typically between 12-18-GHz band is improved. The antenna gain, radiation pattern, and input reflection performance measurements are presented with comparisons.

Parametric analysis of H-plane horn antenna radiation

In this paper, radiation characteristics of H-plane horn antenna are investigated for different structural parameters such as, waveguide width, horn length, flare angle, wall thickness, and source position. The ARM procedure is used for the 2D analysis of the antenna as a fast, accurate and stable numerical technique. The algorithm is firstly verified with analytical data for testing calculation errors. The effects of fundamental parameters of the horn antenna radiator are shown in near and far field performance results.

Ultra wide band TEM horn antenna designs for ground penetrating impulse radar

This paper deals with ultra-wide band (UWB) TEM horn antenna types, which are suitable for hand-held and vehicle mounted impulse GPR systems. On this scope, conventional, dielectric loaded, Vivaldi form, multi-sensor adaptive and array configurations of the TEM horn structure are designed, simulated and measured. Vivaldi shaped TEM horn fed ridged horn and parabolic reflector antenna prototypes are proposed to reach hyper-wide band impulse radiation performances from 300 MHz up to 20 GHz for multi-band GPR operation that can provide high resolution imaging. The gain and input reflection performances are demonstrated with measurement results.

Development of signal processing techniques for through-wall imaging radar systems

This paper presents some adaptive signal processing and synthetic aperture radar (SAR) imaging techniques for ultra-wide band (UWB) ground penetrating radar. Novel UWB antenna structures are used in this work. Raw and processed data collected by experimental studies of through-wall imaging (TWI) scenarios are demonstrated in B-scan and C-scan target detection images.

High resolution signal processing techniques for millimeter wave short range surveillance radar

In this paper, we investigated adaptive signal processing algorithms for high-resolution imaging of short range targets by 24 GHz millimeter wave (MMW) surveillance radar system. For test measurements, a step frequency continuous wave (SFCW) based Synthetic Aperture Radar (SAR) imaging system has been developed by using Anritsu MS4644A Vector Network Analyzer (VNA) and A-scan radar data were collected to demonstrate B-scan target images. We applied SAR processing and MUSIC (Multiple Signal Classification) algorithm for raw data to enhance the cross-range and range resolutions, respectively. The fusion of SAR and MUSIC algorithms is proposed to obtain improved image quality for better target identification and false alarm rate performance.

Front-end design for Ka band mm-Wave radar

In this paper front-end design for a Ka band milimeter wave (MMW) radar which consists of an antenna, a low noise amplifier (LNA) and a band pass filter is presented. The operation frequency of the designed system is between 24-25 GHz in Ka band. A high gain axially displaced elliptical (ADE) dual reflector antenna is employed on the antenna structure. ADE sub-reflector with 5 cm diameter is illuminated by a feeder horn and a main reflector 30 cm diameter parabola focuses incoming waves from the ADE sub-reflector. According to the simulation results narrow half power beam width (HPBW=30) and high gain (G=35 dBi) are obtained with good efficiency (%58). An HJ-FET that has low noise figure (NF<;1 dB) and high gain (>13 dB) is utilized to design a LNA. Double transistors are connected as cascaded to achieve higher transducer gain (Gt>19 dB). Matching circuits and feeder resonators are designed by microstrip lines to obtain low input and output VSWR (Vin<;2.1, Vout<;2.1). A microstrip band pass filter (BPF) is designed to receive required signals and to suppress other bands. The BPF is formed by combination of a radial stub low pass filter (LPF) and a short stub high pass filter. Low insertion loss (S21>-2.5dB) and low return loss (S11<;-15 dB) are aimed to take signal as lossless as at pass band. The simulated designs are manufactured and measured. It is seen that there are good agreements between measurement and simulation results.

SAR imaging techniques for ground penetrating impulse radar

This paper presents synthetic aperture radar techniques for impulse ground-penetrating radar system. For test measurements, we used ultra-wide band impulse ground-penetrating radar system to collect A-scan radar data and these data was demonstrated in B-scan image. Synthetic aperture radar algorithm was applied to advance the cross-range and range resolutions.

Millimeter wave short range radar system design

In this paper, a 24 GHz millimeter wave (mm-wave) short range radar system is presented. In the designed radar system, there is one transmitter and one receiver channel. The transmitter channel has +9 dBm output power and 24 GHz output carrier signal is modulated with 20 ns square wave by SPDT switch. At the receiver channel, there are two LNAs, which have totally 40 dB gain, a microstrip band pass filter (BPF) and a double balanced IQ mixer. The designed radar system is measured using an oscilloscope at output of IF channel. According to the results, it is seemed that 200 mV and 50 mV reflection levels are received from metal and human target, respectively, at 2 meters without IF amplifier. ADE reflector antennas and horn antennas are utilized for transmitting and receiving.

Quasi TEM-Horn antenna array for rescue radar buried victims under rubble

In this paper, it is presented that quasi TEM-Horn antenna array to rescue buried victims under rubble. Designed antenna array, which consists of 4 elements, is operated between 400 MHz and 2 GHz. In order to penetrate electromagnetic wave into rubble, lower frequencies like 400-500 MHz should be used, because of attenuation of the concrete. Besides, it is required that ultra-wide band operation for good resolution while searching a buried victim. As an element of the array, quasi TEM-Horn antenna is utilized. Total dimensions of the array antenna are 14 cm × 27 cm × 57 cm. Distance between each element is 14 cm and also there is a reflector behind the antennas. Antenna gain is started from 8 dBi at 400 MHz and is increased till 14 dBi at 2 GHz. Furthermore, VSWR of the antenna is mostly fewer than 2 at the operation band, but at some frequencies it reaches 3. Reflector, which is placed 6 cm behind the array, is not only providing gain enhancement, but also reducing back lobe radiation at lower frequencies and shielding. Moreover array elements could be employed to understand which way the target is using A-scan data.

The design and simulation of a compact Vivaldi Shaped Partially Dielectric Loaded (VS-PDL) TEM Horn antenna for UWB applications

Ultra wide band (UWB) antennas are of huge demand and Vivaldi antennas as well as the TEM Horn antennas are good candidates for UWB applications as they both have relatively simple geometry and high gain over a wide bandwidth. The aim of this study was to design such an antenna that achieves the maximum antenna gain over a bandwidth between 1 GHz to 10 GHz while minimizing the size of the antenna. The idea was to make use of combined respective advantages of Vivaldi antennas and TEM Horn antennas to achieve the desired goals by shaping the TEM Horn antenna to look like a Vivaldi antenna. The antenna structure was modified by partially dielectric loading it in the center to increase the gain and bandwidth. It was placed in a surrounding box made of PEC material to reduce the undesired side lobes to obtain a more directive radiation pattern. The simulations were performed by using the CST STUDIO SUITE Electromagnetic (EM) Simulation software. The results showed that the Vivaldi Shaped Partially Dielectric Loaded (VS-PDL) TEM horn antenna with 5 cm aperture depth had the best gain values over the desired bandwidth. This antenna is considered as compact enough for applications like hand-held impulsive Ground Penetrating Radar (GPR) and Electromagnetic Compatibility (EMC) measurement systems due to its reduced size and shielded metallic box structure.