Dielectric Sheets Covered Broadband Vivaldi Antenna for Gain Enhancement

Abstract

Abstract-To enhance the gain of conventional Vivaldi antenna (CVA), a novel dielectric sheets-covered Vivaldi antenna (DSCVA) is proposed. The dielectric sheets suck energy from the tapered slot region and flare termination region of the CVA, and thus act as surface wave antennas to improve end-fire performances. The CVA, DSCVA as well as the DSCVA with elongated tapered profile (SP-DSCVA) are designed, fabricated and measured. The simulation results are in good agreement with the experimental data. Measurement results show that the gain increase of the DSCVA is up to 5.1 dBi in the range of 3.5-16.5 GHz without increasing antenna length compared to the CVA. More gain enhancement is achieved for the SP-DSCVA. In addition, the half power beamwidths of the CVA as well as the sidelobe levels are improved in both E-and H-planes.

Design of an antipodal Vivaldi antenna with fractal‐shaped dielectric slab for enhanced radiation characteristics

“…Table listed a comparison between proposed antenna and previously reported related articles. When the proposed antenna compared with those in References 5–9, 11, and 13, then it provides higher gain than these and in terms of compactness, it is much more compact than those in References 5, 7, 8, and 13. It is also seen that the bandwidth of the proposed antenna is wider than those in References 2, 5–9, 11, and 13.…”

“…Dielectric slabs of different shapes show little effect on the performance of the CAVA at high frequency. To achieve better performance, the fractal shape is used on the dielectric slabs because due to space‐filling properties of the fractal, it enlarges the electrical length of the dielectric slab without involving additional physical area .…”

“…To achieve higher gain in wide frequency range along with improved radiation characteristics, fractal‐shaped dielectric slabs are placed on both sides of the antenna substrate. Normally, a Vivaldi antenna is a surface wave antenna, which belongs to the class of traveling wave antennas . It is demonstrated in Figure that the EM waves propagate along the tapered slot of the CAVA as surface waves with phase velocity lower than the speed of light that radiates in the end fire direction; the rest part of the wave radiates into the free space in the form of sky wave.…”

“…Corrugated‐type structure used on the antipodal Vivaldi antenna (AVA) made it appropriate in wider band widths and higher gain applications. To improve the gain of the antenna, a novel method is used in Reference where two elliptical‐shaped dielectric sheets are placed parallel to the antenna. In Reference , a Vivaldi antenna for medical imaging application is presented where the Koch fractal structure etched on the radiator and ground edge makes the antenna more directive, which is appropriate for imaging applications.…”

“…2 Nowadays, Vivaldi antennas that was introduced by Gibson 3 is one of the suitable candidates used for wide band applications, medical imaging techniques, radio telescopes, and radar communication due to its promising properties such as broad operating bandwidth, planar structure, directive radiation pattern, and ease of manufacturing. 4 But some challenging issues of Vivaldi antenna, which draw attention of many researchers, 2,[5][6][7][8][9][10][11][12][13] include lower gain at high-frequency range and unstable radiation patterns.…”