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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 hig...
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... far-field radiation patterns of the both antennas are measured in an indoor anechoic chamber. Fig. 7 plots E- and H-plane radiation patterns of BAVA and DL-BAVA at 3, 6, 10, 13 and 18 GHz. Having a low dynamic range at upper frequencies in the measurement system, the simulation and measurement do not follow at these frequencies. Therefore simulation results for 18 GHz are not included in the plots. For both conventional BAVA and ...
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A new design of an E-plane double-element Vivaldi antenna with sum and difference radiation patterns is presented in this paper. The antenna operates in the frequency range of 2.3GHz to 15GHz (ratio of 6.5:1) with the highest grating lobe level of -10dB at 15GHz and competitive gain performance from 6.8dBi at 2.3GHz up to 14.7dBi at 15GHz. The grat...
Citations
... Different design techniques are utilized to modify the AVA's geometry to extend the frequency band's low end [3,10,15,18]. For instance, Peng Fi et al. [6] have employed tapered slot edges to enhance lower-end bandwidth and radiation characteristics within the lower frequency spectrum. ...
... Firstly, for the gain enhancement method using a parasitic metallic patch, various patch shapes, such as an elliptical, a diamond-shaped, or in multiple strips, were appended either inside the tapered slot or above the tapered slot [30][31][32][33]. Secondly, a dielectric lens/cover with different shapes, such as a half-elliptical shaped, a trapezoidal shaped, an exponential shaped, or a combination of two fan-shaped and a half-circularshaped slots, was applied to enhance gain [34][35][36][37][38][39][40]. Thirdly, for a metamaterial loading/lens, different unit cell shapes, such as a meander-line, a modified split ring, a modified parallel line, or a rectangular patch, were used [41][42][43][44][45][46][47][48]. ...
In this paper, two kinds of miniaturization methods for designing a compact wideband tapered slot antenna (TSA) using either fan-shaped structures only or fan-shaped and stepped structures were proposed. First, a miniaturization method appending the fan-shaped structures, such as quarter circular slots (QCSs), half circular slots (HCSs), and half circular patches (HCPs), to the sides of the ground conductor for the TSA was investigated. The effects of appending the QCSs, HCSs, and HCPs sequentially on the input reflection coefficient and gain characteristics of the TSA were compared. The compact wideband TSA using the first miniaturization method showed the simulated frequency band for a voltage standing wave ratio (VSWR) less than 2 of 2.530–13.379 GHz (136.4%) with gain in the band ranging 3.1–6.9 dBi. Impedance bandwidth was increased by 29.7% and antenna size was reduced by 39.1%, compared to the conventional TSA. Second, the fan-shaped structures combined with the stepped structures (SSs) were added to the sides of the ground conductor to further miniaturize the TSA. The fan-shaped structures based on the HCSs and HCPs were appended to the ground conductor with the QCSs and SSs. The compact wideband TSA using the second miniaturization method had the simulated frequency band for a VSWR less than 2 of 2.313–13.805 GHz (142.6%) with gain in the band ranging 3.0–8.1 dBi. Impedance bandwidth was increased by 37.8% and antenna size was reduced by 45.9%, compared to the conventional TSA. Therefore, the increase in impedance bandwidth and the size reduction effect of the compact wideband TSA using the second miniaturization method were better compared to those using the first method. In addition, sidelobe levels at high frequencies decreased while gain at high frequencies increased. A prototype of the compact wideband TSA using the second miniaturization method was fabricated on an RF-35 substrate to validate the simulation results. The measured frequency band for a VSWR less than 2 was 2.320–13.745 GHz (142.2%) with measured gain ranging 3.1–7.9 dBi.
... The next technique involves dielectric lenses at the front of the Vivaldi antenna, which helps enhance the antenna gain and reduce sidelobes by minimizing the aperture phase error, such that the outgoing phase fronts are almost planar. There have been many examples of dielectric lenses in the literature [22]- [31]. These lenses can either be 2D-planar (i.e., on the same plane as the dielectric substrate of the Vivaldi antenna) or 3D, and can have various shapes like elliptical [22]- [23], circular [24], rectangular [25], diamond-shaped [26], rod-shaped [27], trapezoidal [28]- [30], and spherical-axicon [31]. ...
... There have been many examples of dielectric lenses in the literature [22]- [31]. These lenses can either be 2D-planar (i.e., on the same plane as the dielectric substrate of the Vivaldi antenna) or 3D, and can have various shapes like elliptical [22]- [23], circular [24], rectangular [25], diamond-shaped [26], rod-shaped [27], trapezoidal [28]- [30], and spherical-axicon [31]. The circular lens in [24] employed multiple dielectric layers of different relative permittivities in order to enhance gain. ...
A broadband balanced antipodal Vivaldi antenna (BAVA) has been reported along with a novel 3D-printed shaped dielectric lens (SDL) for aiding in gain enhancement, largely towards the higher frequencies. The complete BAVA with SDL (BAVA-SDL) structure exhibits a broad simulated bandwidth of 3.8 GHz to over 60 GHz (>15.8:1). The 3D SDL enables an ever-increasing gain profile by compensating for the large phase errors that occur particularly at higher frequencies over a wide range of 45–60 GHz. The maximum simulated broadside gain reaches 24 dBi at 54 GHz. A Digital Light Processing (DLP) based 3D printing technique has been used to fabricate the SDL, where periodic unit lattice cells with air inclusions have been implemented for manipulating the corresponding relative permittivity. Measurements could be carried out until 45 GHz due to limitations from the fabrication process. Nevertheless, the measured results were found to be in very good agreement with their simulated counterparts.
... A simple technique of substrate end shaping was presented in a previous article [17], which corrects the tilted bean and low axial gains of the antenna in the upper working frequencies. A method that significantly improved the antenna gain in high frequencies by applying an elliptical dielectric lens in front of the balanced antipodal Vivaldi antenna's aperture was proposed in [18], but this approach greatly increased the antenna's profile. Recently, several methods for designing dielectric lenses have been proposed. ...
In order to expand the applications of the traditional Vivaldi antenna by addressing the low gain of the traditional Vivaldi antenna, this paper combines the phase distribution of the Vivaldi antenna aperture based on the analysis of the transmission characteristics of a dielectric unit by utilizing the advantages of artificial electromagnetic material. A more reasonable method of loading a dielectric lens is proposed and utilized in combination with edge grooving. A comparison of the results shows that the antenna operates in the frequency range of 4 to 16 GHz. The low-frequency boost is approximately 3 dB, and the high-frequency boost is approximately 9.6 dB.
... Multi-decade bandwidth and a higher F/B ratio of more than 35 dB at 40 GHz were additional features of the reported design. The research on antipodal Vivaldi antennas showed that the F/B ratio can be improved by adding a trapezoid-shaped lens, spherical cone lens [3], dielectric lens [11], or etching slots [12]. These techniques focus the radiation beam of the Vivaldi in the desired direction using the specific profile of the dielectric material. ...
A novel wideband multilayer dual‐podal Vivaldi antenna with broadband characteristics from 5.5 to 20.82 GHz, is presented. Contrary to traditional Vivaldi antennas that are antipodal‐based, this design is realised by placing a pair of podal Vivaldi antennas with corrugated slots on the top and bottom of a substrate stack (consisting of two dielectric layers) using a Bondply. The pair is fed in‐phase with the help of a Strip‐Line (SL) transmission section that is terminated on a radial stub to couple capacitively to the antenna elements. With this technique of electrically coupling a podal Vivaldi pair, improved performance parameters are achieved, specifically: a measured maximum gain of 9.33 dBi, Half Power Beam Width of 126.5° in the H‐plane, and a maximum Front‐to‐Back (F/B) ratio of 14.36 dB with an overall antenna size of 29 × 21 × 1.63 mm. The in‐depth understanding of the working mechanism is supported by a detailed parametric analysis, current distribution, and a clear physical insight into the operating principles. Moreover, a 1 × 4 Vivaldi antenna array is also designed and analysed. A measured maximum gain of the 13 dBi at 15 GHz in the array is achieved along with the wide bandwidth of 6.3 GHz from 10.78 to 17.07 GHz. The array is fed through an SL corporate feed network that ensures in‐phase excitation of all four Vivaldi pairs. A Grounded Co‐planar Waveguide to SL transition is adopted for connecting the 2.92 mm Radio Frequency launcher on the top layer. The very compact geometry of the proposed structure enables its integration into the systems for remote sensing applications.
... However, due to the complexity of the designs, there are no significant works dealing with the coupling reduction of the Vivaldi antenna using EBG, SRR, and metasurface. The use of dielectric lenses [9] and metal director [10] are also investigated to improve the radiation directivity. The dielectric lens or director in the aperture of the AVA can concentrate the energy in the end-fire direction. ...
Millimeter wave (mmWave) is a key band for fifth-generation (5G) mobile communication that features large available bandwidth and high data rates. Antenna elements are recommended to be dual-polarized, compact, wideband, and high gain to be utilized for 5G array antenna systems. In this paper, a miniaturized gain-enhanced Vivaldi antenna element in an evolutional-oriented process is designed, simulated, and successfully measured for 5G mmWave applications. The size of the antenna is as compact as 5.5mm × 12mm. The measured operational bandwidth of the antenna element is between 22.5 – 45 GHz covering 5G
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frequency bands even though the simulation results reveal the extension of the bandwidth to 70 GHz. The results show a nearly constant end-fire radiation pattern with a measured gain of more than 5dBi across the whole bandwidth. The comparison of the proposed antenna with the most recent related works justifies the novelties and advantages of the antenna in terms of 5G requirements, bandwidth, and compactness properties. The proposed antenna element is a suitable candidate for large antenna arrays and 5G MIMO applications.
... Several techniques have been proposed to improve the gain and reduce the radiation pattern instabilities like main beam split and tilt for ATSAs. In [4], a dielectric lens is placed in front of the tapered section of the balanced antipodal Vivaldi antenna over 3-18 GHz to reduce the beam tilt in E-plane. A dielectric slab is loaded ahead of the taper section of a Substrate Integrated Waveguide (SIW) based curvilinear tapered slot antenna in [5] over [8][9][10][11][12][13] GHz. ...
We present a compact 20–40 GHz antipodal elliptically tapered slot antenna loaded with novel broadband left-handed metamaterial on dielectric lens. The metamaterial unit cell comprises of two split ring resonators and dual thin wire structure. The metamaterial unit cell is characterized as left-handed over 20–40 GHz frequency. The flare section of the proposed antenna is followed by a dielectric lens in the shape of an isosceles trapezoid, onto which the metamaterial unit cells are loaded. The antenna is fabricated on Rogers RT/Duroid 5880 substrate with a dielectric constant of 2.2. It occupies 30 × 55 × 0.508 mm³ volume. The proposed antenna exhibits a reflection coefficient (|S11|) < − 10 dB and 15.7 dB gain at the highest frequency of 40 GHz. The antenna is compact in size and demonstrates high gain and stable radiation pattern in both E- and H-plane. The suitability of the proposed antenna for wideband millimeter wave imaging is demonstrated for detection of concealed weapons and defects in structures.
... Various types of antennas that can be used to detect breast abnormalities for imaging systems have been described in the literature. [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] In ref [16], a new design of circular patch antenna is suggested which is compared to the microstrip patch antenna. The radiation pattern and the gain values obtained was however not adequate to provide MI with good quality of signal range. ...
... Thus, it needs a higher bandwidth for the construction of a superior quality image 28 and mitigation of distortion when transferring short-term pulses. 29 Figure 2 reveals a MI system, which dips into a vigilantly complex coupling liquid for better signal penetrating by the antenna which is utilized for the sensor. It allows the dynamic spectrum of image modality to be expanded. ...
This article presents a novel CPW fed ultrawideband (UWB) antenna for detection of unwanted tumor cells in the human breast. Here, a compact and miniaturized UWB antenna employed with dodecagonal edges is proposed for broadening the bandwidth from 2.26 to 13.71 GHz (measured fractional bandwidth of about 143.39%). The antenna is designed on a durable RT 5880 substrate having 0.254 mm thickness, efficiency of 85% and gain of 3.84 dBi. For its flexibility characterization, the prototype of the fabricated antenna is analyzed in both the flat and bending configurations. The simulated testing is carried out by permitting the antenna to emit radiation in conjunction to the human breast phantom to obtain desired antenna characteristics for the microwave imaging (MI) applications. The changes in reflection coefficient with the variation of dielectric content of the breast phantom structure are analyzed. The suggested antenna for MI technique is apt for human exposure because the antenna bids the highest SAR value of 0.932 W/Kg at 10.6 GHz. Moreover, the proposed antenna is flexible, compact and low‐profile with low SAR values that can be useful for breast cancer detection.
... Directional radiation pattern with high efficiency, wide impedance covering bandwidth from 3.1 GHz to 10.6 GHz for better penetration, and high-fidelity factor (FF) [6]. Various design approaches such as tapered slot [7], staircase shaped corner radiator with + slot [8], vivaldi antennas [9][10][11], monopole [12,13], defected ground structures [14,15], horn antennas [16,17] have been presented for UWB technology. Though the aforementioned antennas occupied UWB spectrum, these structures have some limitations like low efficiency, gain and low directivity. ...
Microwave imaging (MWI) is the critically significant practice for the exposure of primary stage cancer in breast. It helps to lessen the figure of mortalities related with breast cancer. A proper sensor is a central facet of the designing of the MWI system for high-resolution images. In this article, an UWB antenna with operating frequency range of 8.4 GHz (3.1–11.5 GHz) is designed and evaluated for microwave imaging of breast tissue. Partial ground plane of tapered slot patch radiator is modified by printing a tapered slot in it, which helped to achieve good and stable impedance matching at the UWB spectrum. Backscattered signal variation is evaluated with and without the existence of malignant cell in the breast tissue. Stable and linear time domain performance of the proposed antenna makes it suitable for microwave imaging technique.KeywordsTapered slotUWBMicrowave imagingTumour detectionBackscattered signal
... The proposed antenna has a nearly flat group delay response, as shown in Figure 3B. According to Table 2, when compared with the referenced Vivaldi antennas in References [34,36,38], the proposed antenna has a similar group delay response. Hence, in the study of Reference [35], the group delay response of the Vivaldi antenna has a flat response with narrowband discontinuities up to 5 ns. ...
In this study, broadband, with a reconfigurable pattern, a slot edge all‐metal Vivaldi antenna (SEMVA) is proposed. The designed antenna is fabricated from an aluminum plate. Then the antenna is measured in an anechoic chamber using a spherical near field measurement system. In the first step, the metal Vivaldi antenna without slots is designed as a reference model. The scattering parameters and the radiation pattern results show that the antenna exhibits poor vswr and deteriorated radiation patterns at the lower operating band. In order to overcome these performance problems, the slot edge technique is successfully adapted to the metal Vivaldi antenna. This technique provides wider bandwidth with vswr <2 and a directive radiation pattern at lower operating frequencies. The dielectric material (Rexolite) can also be inserted into the slots of the designed antenna to improve bandwidth and beamwidth. The proposed antennas with and without dielectric insertion are measured and compared. The measurement results show that using slots increase the bandwidth of the designed antenna from 6:1 to 10:1. The proposed antenna operates between 1.38 and 13.8 GHz with a proper end‐fire radiation pattern. In addition, the power handling capacity of the SEMVA is calculated and compared with PCB antennas.
