RC-Loaded Bow-Tie Antenna for Improved Pulse Radiation

Abstract

Abstract-In this paper, a loading technique for improving pulse radiation from bow-tie antennas is introduced. This technique allows transmission of short transient pulses with very small latetime ringing and relatively high radiation efficiency. It makes use of a combination of a constant resistive loading along the antenna and a capacitive loading with linearly increasing reactance toward the antenna ends. The constant resistive loading is applied using volumetric microwave absorbers to cover one side of the antenna and the linear capacitive loading is realized by constructing narrow slots on the antenna surface. Relatively high radiation efficiency is achieved by choosing the location of the slot nearest to the feed point in such a way that radiation from it combines constructively with radiation from the feed point. Using a 0.8-ns monocycle for excitation, the technique results in a level of late-time ringing of lower than 40 dB and at the same time the peak value of the transmitted pulse is 54% higher than that of the same antenna without loading.Index Terms-Bow-tie antennas, capacitive loading, resistive loading, ultrawide-band antennas.

Improving the GPR Detectability Using a Novel Loop Bowtie Antenna

“…Another approach is to provide a continuous loading profile that increases towards the antenna end, which is found to be very good for pulse radiation. Many designs of resistive loaded bowtie antennas are available in the literature [7]- [9]. In this paper, we examine the detection capabilities of RC loaded bowtie and a novel loop loaded bowtie in an experimental GPR setup.…”

Using end reflections to improve the pulse radiation efficiency of bow-tie antenna

“…The radiated pulse consists of main pulse and end reflection [2]. Main pulse is the only part can be used for probing objects, while end reflection can mask object reflections and should be suppressed by absorbing [3,4]. From the viewpoint of probing objects, therefore, the antenna radiation efficiency of impulse GPR can be indicated by the peak value of the main pulse.…”

“…It has been proved that, the energy of main pulse is less than 30% of the whole radiated energy [3]. Some efforts have been devoted to improve radiation efficiency by increasing the energy fed into the antenna [5], or decreasing the dissipated energy in suppression [3,4], which attracts the most attention. However, a more promising method should be exploiting the considerable energy in end reflections, which is rarely reported in literatures.…”

“…However, a more promising method should be exploiting the considerable energy in end reflections, which is rarely reported in literatures. Lestari's design [4,6] can be considered to belong to this category. But the radiation is optimized according to the central frequency of the exciting pulse, which is always of ultra wide band (UWB).…”

Resistive and Inductive Loading Techniques on Microstrip Antenna for Wideband Application

“…However, this technique decreases radiation efficiency because of dissipating currents. Capacitive loading [2] that is realized on a planar structure, such as a bow-tie antenna with a slot perpendicular to the current direction, has been proposed to improve radiation efficiency. However, in the case of a microstrip antenna with a narrow strip, capacitive loading is not appropriate because the slot has low capacitance.…”