A compact antipodal Vivaldi antenna (AVA) with the dimension of $42 \times 36 \times 1.6~\hbox{mm}{^3}$ is proposed in this letter. Structural modifications in the radiating fins have increased the electrical length thereby reducing the lower operating frequency from 5.2 GHz to 3.7 GHz. Proposed antenna maintains $-20~\hbox{dB}$ copolarization to cross-polarization ratio throughout the operating bandwidth. The prototype is fabricated and the measurement results are presented to validate the performance of the proposed AVA.

A Compact Antipodal Vivaldi Antenna for UWB Applications

This paper presents a comparative review study on ultra-wideband (UWB) antenna technology for Ground Penetrating Radar (GPR) applications. The proposed antenna designs for UWB ground penetrating radar include a bow-tie antennas, Vivaldi antennas, horn antennas, planar antennas, tapered slot antennas, dipole antennas, and spiral antennas. Furthermore a comprehensive study in terms of operating frequency range, gain and impedance bandwidth on each antenna is performed in order to select a suitable antenna structure to analyze it for GPR systems. Based on the design comparison, the antenna with a significant gain and enhanced bandwidth has been selected for future perspective to examine the penetration depth and resolution imaging, simultaneously suitable for GPR detection applications. Three different types of antennas are chosen to be more suitable from the final comparison which includes Vivaldi, horn and tapered slot antennas. On further analysis a tapered slot antenna is a promising candidate as it has the ability to address the problems such as penetration depth and resolution imaging in GPR system due to its directional property, high gain and greater bandwidth operation, both in the lower and higher frequency range.

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Ultra-Wideband Antenna Design for GPR Applications: A Review

In this letter, a novel antipodal tapered slot antenna (TSA) for ultra-wideband (UWB) applications is proposed. A folded fin structure is employed in the design for realizing wider bandwidth. Generally, UWB antennas have difficulty in its miniaturization because the lower-limit frequency reaches to 3.1 GHz. The lower-limit is determined by its total fin width. The folded fins realize both the lower limit and a compact size. We demonstrate the wideband characteristics in experiments. Its dispersion characteristic is also measured and discussed.

Compact Folded-Fin Tapered Slot Antenna for UWB Applications

The design of an ultra-wideband antipodal Vivaldi antenna to operate at frequency range from 2.1 GHz-27 GHz for microwave imaging applications is proposed in this paper. It includes regular triangular slits and opening rate of the aperture that extends the lower end of frequency band limitation and improves the radiation characteristics. Good radiation characteristics in terms of improvement of front-to-back ratio and gain are achieved. A prototype of the proposed antenna is fabricated and tested. The result of measurement of magnitude of reflection coefficient is in a good agreement with the simulated result. Feasibility of this antenna for the use in microwave imaging technique to obtain high-range resolution images of construction materials is demonstrated.

Design of Ultra-Wideband Antipodal Vivaldi Antenna for Microwave Imaging Applications

A novel approach of improving the impedance matching at lower frequencies of antipodal Vivaldi antenna by Chebyshev tapering is presented in this work. The conventional antipodal Vivaldi antennas are modified by Chebyshev tapered loading which yields an extremely large impedance bandwidth from 1 GHz to 35 GHz, with percentage bandwidth of 189%. The antenna has an overall dimension of 100 mm × 100 mm. The proposed structure shows peak gain of 6.8 dBi and has fairly stable radiation pattern throughout its operating bandwidth. A fabricated prototype is developed and measured characteristics are in good agreement with simulated results.

A super wideband Chebyshev tapered antipodal Vivaldi antenna

Vivaldi antenna is a traditional ultra-wideband(UWB) antenna, and this paper focuses on designing its structural parameters properly to balance the bandwidth, gain, cross-polarization and other key parameters. By studying the effects of various parameters on the antenna performance, a compact Vivaldi antenna for ultra-wideband system is designed and realized. The antenna has a small size, high gain and small cross-polarization characteristics compared with the antannas in the relevant references, and it can meet the requirements of UWB system.

An antipodal Vivaldi antenna for ultra-wideband system

Meat quality and its detection is very important to the improvement of people's life level, especially, nondestructive testing techniques to detect meat quality are focus to researchers of home and abroad constantly. This paper introduces the measuring method in this field, and then the improvement and new trends of nondestructive testing techniques for quality detection of meat were also summarized. With the development of microwave techniques, it has been used widely in the detection of food quality. In this paper a methodology for testing the quality of pork using microwave techniques is presented. By observing the effect of injecting water into pork and the process of putrefaction of pork, the measured S21 of pork samples exhibit certain variation trend and can be used to inspect its quality. This technique can be further developed for commercial purpose and has good prospect in the future.

Gang Ji

Papers

An antipodal Vivaldi antenna for ultra-wideband system

Study of water-injected pork and pork freshness using microwave techniques