Dielectric lens balanced antipodal Vivaldi antenna with low cross‐polarisation for ultra‐wideband applications

Abstract

The major deficiency of conventional ‘balanced antipodal Vivaldi antenna’ (BAVA) is its tilted beam over upper working frequencies. This study reports on a new BAVA to overcome this defect. By applying a dielectric lens in front of the antenna's aperture, beam‐tilting in E‐plane was improved within the ultra‐wideband frequency range, as well as higher frequencies. In the new BAVA, the authors have also achieved an acceptable cross‐polarisation. Measurements show that the antenna has better than 10 dB return loss within the aforesaid frequency range. The measurements successfully verify the simulation results. Group delay and fidelity factor as time domain characteristics of the proposed antenna have been studied. They have compared performance of the conventional BAVA, with achievements of the new BAVA as hereunder.

An Overview of Uwb Antennas for Microwave Imaging Systems for Cancer Detection Purposes

“…One of the main challenges in the design of these antennas is related to the physical size in order to allow a greater number of antennas to collect more information of the scattered signal for a successful image reconstruction, as well as to achieve a wider bandwidth to get a high-resolution image [20] and reduce the distortion in transmission of short-duration pulses [21]. Several antennas were proposed for cancer detection as monopole antennas [14,22], fractal antennas [23][24][25][26], antipodal Vivaldi antennas [27], slot antenna [28,29], and patch antenna [30], as will be described below.…”

“…Figure 32 shows an antenna that includes a lens with dielectric properties same as the antenna (Arlon AD255 ε r = 2.55). The innovation is based on the elliptical shape dielectric lens which joints in front of the antennas aperture [21]. As in the previous design [80], the antenna consists of three components and two substrate layers, and two metal components serve as ground planes while the middle patch is the active conducting component [21,80].…”

“…The innovation is based on the elliptical shape dielectric lens which joints in front of the antennas aperture [21]. As in the previous design [80], the antenna consists of three components and two substrate layers, and two metal components serve as ground planes while the middle patch is the active conducting component [21,80]. The elliptical shaping reduces the mismatch due to the dielectric-air interface, and the peak gain of the structure of Figure 32(b) is approximatively 12 dB [21].…”

Wideband Balanced Antipodal Vivaldi Antenna With Enhanced Radiation Parameters

“…In practice, as the frequency increases, different issues occur, which degrade the radiation properties. For example, the beam-squinting mainly caused by the difference in the dielectric loading of the ground flares (top and bottom layer) compared to the signal flare (middle layer) and the unbalanced current distribution after the transition from the stripline to the start of the flares [19] result in bad directivity in high frequencies. Besides, the phase reversal of current traveling along the flare at high frequencies and some undesired radiation also severely deteriorate the radiation properties of BAVA.…”

Dielectric Sheets Covered Broadband Vivaldi Antenna for Gain Enhancement

“…The coplanar lens produced by substrate end shaping technique, director made of a profiled dielectric piece with higher permittivity, hemisphere lens placed in front of the antenna, and metal director formed by parasitic patch have been proposed to produce directed radiation pattern and enhance antenna gain [5][6][7][8][9][10][11]. The corrugation edge technique is proposed to improve radiation features of lower frequencies [12][13][14].…”