DESIGN OF MODIFIED 6-18 GHz BALANCED ANTIPODAL VIVALDI ANTENNA

Abstract

Abstract-In this paper, a modified planar balanced Vivaldi antenna with endfire characteristics near the metal surface is proposed for 6-18 GHz applications. The proposed antenna structure consists of three copper layers, among which two external layers locate on the two outsides of two dielectric substrates, and the central layer is sandwiched by these two dielectric substrates. To further enhance the end-fire radiation characteristic, a number of novel techniques are proposed, including elongation and shaping of the supporting substrate of a conventional balanced antipodal Vivaldi antenna beyond its aperture, using an I-shaped slot loaded radiation patch and cutting a triangle on the edge of three copper layers. Measured and simulated results show that the proposed antenna not only exhibits good impedance bandwidth, but also improves the end-fire performance in the operational frequency of 6-10 GHz and achieves high gain in the end-fire direction, low cross-polarization and high front-to-back (F-to-B) ratio.

A Compact High-Gain and Front-to-Back Ratio Elliptically Tapered Antipodal Vivaldi Antenna With Trapezoid-Shaped Dielectric Lens

“…In some cases, the directors have been used with higher dielectric constant than that of the antenna substrate to direct most of the energy toward the aperture center [9,10]. However, the improvement on the antenna gain is limited to the frequency band up to 30 GHz [10][11][12][13], with relatively low gain. Another main factor which can be vital in some practical applications, especially in microwave imaging applications, is front-to-back (F-to-B) ratio.…”

“…However, these antennas have low gain in entire band or in some cases at lower Manuscript frequencies [5][6][7][8] as shown in Table I. The dielectric director [9] and lens [10][11][12][13][14] are used to improve the antenna gain, especially at the higher frequencies; their obtained gain values are also summarized in Table I. In some cases, the directors have been used with higher dielectric constant than that of the antenna substrate to direct most of the energy toward the aperture center [9,10].…”

“…The prominent option for this purpose is the use of Vivaldi antenna [4] since it has wide bandwidth, directional radiation pattern and low profile. Various designs of Vivaldi antennas have been presented in literature; however size reduction, improvement on radiation characteristics, and extension of impedance bandwidth of these antennas are still challenging [5][6][7][8][9][10][11][12][13][14]. For instance, in [5] a stepped connection structure is applied between slotline and tapered patches to improve impedance bandwidth.…”

Design of a Microwave Time Reversal Mirror for Imaging Applications

“…A comparison of the performance (fractional bandwidth (BW), maximum size (ρ) and maximum gain (G)) of the designed antennas with Vivaldi and planar monopole antennas described in the literature is presented in Table 1. It is observed that the achieved gain of the SE-APV antenna is much more than that of the antennas presented in [14,15], while maintaining a small size and comparable BW. Similarly, the RGSR antenna achieves higher gain and BW than the UWB antennas proposed in [7,19], while maintaining a comparable size.…”

“…With the Vivaldi antenna, the bandwidth limitation due to the microstrip to slot-line transition can be removed by choosing a proper feed. One solution used in this manuscript is to use a microstrip to stripline or a two-sided slotline transition [13], as recently used by many researchers [14,15]. Thus, no external balun is required to operate with unbalanced transmission lines that are typically used as microwave feed networks [16].…”