Search

An arc-shaped distributed multilayer capacitive loading structure combined with resistive loading is presented in this paper to enhance the radiation performance of folded bowtie antenna (FBA). The radiation efficiency of the loaded bowtie antenna (BA) is improved, and the low-frequency bandwidth is broadened by the bent loop circuits. Additionally, a novel technique of cavity groove is proposed to design the reflector. The optimized cavity tightly coupling with the radiation part overcomes the shortcomings of conventional cavity-backed BAs. The improved ultra-wideband (UWB) FBA with low profile is then designed and fabricated. The basic geometry of the proposed antenna is combined by a novel acorn-shaped bent bowtie patch and a hollowed stepped back cavity. The simulated -10 dB impedance bandwidth of the proposed antenna is over 100 MHz-1100 MHz while the measured operating bandwidth is 250 MHz-850 MHz. This BA of folded type obtains a high realized gain of 4 dBi at 850 MHz and a narrow pattern over the whole band. Time-domain measurements and field tests for practical ground-penetrating radar (GPR) applications have been carried out and the results demonstrate the advanced performance.

Ground penetrating radar (GPR) is a special type of radar, which uses electromagnetic (EM) wave to detect the buried objects in the shallow subsurface. The overall efficiency and performance of the GPR system significantly depend on the quality of the acquired data and hence on the antenna and transceiver electronics sensor used in GPR surveying. Bow-tie antennas are widely used for GPR applications, as they possess a set of stringent antenna performances such as a low frequency of operation, ultra-wideband performance, minimal ringing, compact, planner, and lightweight. In this article, a comprehensive review of the bow-tie antennas used for GPR applications is presented. A brief review of the theoretical analysis of the bow-tie antennas indicates the advantageous features of this type of antennas with elliptical structures over the traditional triangular shapes. A comparative analysis of popularly used feed networks confirms that there is a requirement of a balun (balanced to unbalanced) which is used to convert the unbalanced current flow of the coaxial cable to the balanced current flow of two symmetrical lines used for exciting a balanced antenna. A comparative analysis of design techniques used to improve the traditional bow-tie antennas to overcome the various limitations, such as end-fire reflections, narrow bandwidth, dispersion characteristics, low efficiency, and gain, is presented. There is ample scope to propose a novel bow-tie antenna or to improve the existing Bow-tie antennas to achieve compactness, lightweight, reduced end-fire reflections, dispersionless characteristics, better gain and directivity, high radiation efficiency, and so on. [ABSTRACT FROM AUTHOR]