Vivaldi Antenna Research Articles

A Miniaturized and High-gain Antipodal Vivaldi Antennas Using Directors

A Miniaturized and High-gain Antipodal Vivaldi Antennas Using Directors

Bandwidth, Gain Improvement, and Notched-Band Frequency of SWB Wave Coplanar Vivaldi Antenna Using CSRR

Bandwidth, Gain Improvement, and Notched-Band Frequency of SWB Wave Coplanar Vivaldi Antenna Using CSRR

Four‐port MIMO Vivaldi antenna for access points

AbstractIn this article, a 4‐port multiple input, multiple output (MIMO) antenna array is presented, based on a Vivaldi design for nonplanar applications like access points above 6 GHz. The antenna is configured with four Vivaldi antennas arranged orthogonally, one to each other, to increase the electromagnetic isolation among elements. The Vivaldi element is fed with a microstrip with an integrated balun in only one arm, and each arm is set in an antipodal position to the other, giving an easy‐to‐design and build prototype, with no complicated feeding techniques. Each antenna plane has dimensions of 90 × 40 mm2. The array presents a bandwidth from 5.3 GHz to beyond 20 GHz, with electromagnetic isolation above 20 dB, an envelope correlation coefficient below 0.001 for the entire bandwidth, giving a diversity gain around 20 dB, and a total active reflection coefficient below −10 dB from 7 to 20 dB, fulfilling the metrics for MIMO applications.

Design and Analysis of a Low-profile Tapered Slot UWB Vivaldi Antenna for Breast Cancer Diagnosis

Design and Analysis of a Low-profile Tapered Slot UWB Vivaldi Antenna for Breast Cancer Diagnosis

Mounted Director Element on Dual‐Band Vivaldi Antenna for Wireless Energy Harvesting Application

Mounted Director Element on Dual‐Band Vivaldi Antenna for Wireless Energy Harvesting Application

Design and Development of a High-Gain Broadband Balanced Antipodal Vivaldi Antenna Using a 3D-Printed Shaped Dielectric Lens

Design and Development of a High-Gain Broadband Balanced Antipodal Vivaldi Antenna Using a 3D-Printed Shaped Dielectric Lens

Wearable Wideband Textile Coplanar Vivaldi Antenna for Medical and IoT Application

Wearable Wideband Textile Coplanar Vivaldi Antenna for Medical and IoT Application

Design of Antipodal Vivaldi Antenna for Medical Imaging Application

The microwave imaging (MWI) system in medical applications is commonly used to detect abnormalities in the human body. The purpose of this study was to design an Antipodal Vivaldi Antenna (AVA) for medical imaging applications using MWI. The research method used is based on the AVA design simulation of the CST Studio Suite 2019 application using time and frequency domain methods, which has dimensions of 60x40 mm2 with an antenna structure that works in the frequency range of 6.3-9.6 GHz, the impedance for bandwidth is -10 dB, using Flame Retardant-4 (FR-4) thickness 1.6 mm (= 4.3, tan δ = 0.025) as substrate material. A linear array of antennas was utilized in the simulation, either with or without a phantom. The phantom options include an absence of a phantom (only antennas), a cube-shaped water phantom, and a water phantom containing an anomaly. The result of the simulation on the AVA design produces a bandwidth of 41.61%, a gain of 5.16 dB, a return loss of -26.73 dB, a Specific Absorption Rate (SAR) value of 0.26 W/kg and a graph of S-parameters (S21). It can be concluded that the MWI system using the AVA design in this study has the potential to properly detect the presence of anomalies.

A Simple Microwave Imaging System for Food Product Inspection through a Symmetry-Based Microwave Imaging Approach.

In the food industry, there is a growing demand for cost-effective methods for the inline inspection of food items able to non-invasively detect small foreign bodies that may have contaminated the product during the production process. Microwave imaging may be a valid alternative to the existing technologies, thanks to its inherently low-cost and its capability of sensing low-density contaminants. In this paper, a simple microwave imaging system specifically designed to enable the inspection of a large variety of food products is presented. The system consists of two circularly loaded antipodal Vivaldi antennas with a very large operative band, from 1 to 15 GHz, thus allowing a suitable spatial resolution for different food products, from mostly fatty to high water-content foods. The antennas are arranged in such a way as to collect a signal that can be used to exploit a recently proposed real-time microwave imaging strategy, leveraging the inherent symmetries that usually characterize food items. The system is experimentally characterized, and the achieved results compare favorably with the design specifications and numerical simulations. Relying on these positive results, the first experimental proof of the effectiveness of the entire system is presented confirming its efficacy.

Wideband 0.5–50 GHz double‐ridged guide horn antenna using coaxial‐to‐ridge waveguide launcher

AbstractEver‐increasing bandwidth requirements from various industries drive the need for the ever‐increasing bandwidth of antennas used for testing. Broadband Double‐Ridged Guide Horn (DRGH) antennas are used extensively in antenna measurement and ElectroMagnetic Compatibility/Interference (EMC/I) testing. The current state‐of‐the‐art broadband DRGH antennas reported in the literature for use in measurement applications cover bandwidth ratios as large as 36:1 (0.5–18 GHz). This paper presents the design and realisation of a DRGH antenna with a 100:1 bandwidth ratio (0.5–50 GHz). To achieve such a wide bandwidth, the ridge gap, width and feed were optimised, and a novel coaxial‐to‐ridge waveguide launcher section based on a typical Vivaldi antenna was developed. Backward radiation was reduced using an absorber‐filled cavity. A prototype DRGH antenna was manufactured using additive manufacturing, also referred to as 3D printing. Simulated and measured results obtained in an anechoic chamber are presented.

A novel approach for the generation of OAM beam with high mode purity using the reflectarray

In this paper, a reflectarray composed of 14 × 14 unit elements is proposed for generating orbital angular momentum (OAM) beam (l = +1) at 5.75 GHz with reduced phase errors and side lobe levels. Unlike traditional designs, the proposed reflective surface is made up of two different types of unit cell structures. Together, the two-unit cells can offer a complete 360°phase range with linear slope as a function of the phasing element size. The proposed reflectarray prototype is 350 mm×350 mm in size, it is fabricated on commercial FR4 laminates, and experimentally tested. Additionally, antipodal vivaldi (AV) antenna is considered as the feed for the proposed reflective surface. The experimental results confirm that the OAM vortex beam with l=+1 is successfully generated at 5.75GHz. The generated OAM beam has a high mode purity, with a gain of 15dBi and divergence angle of ± 8°.

Influence of Aperture of Radiating Strip Structure on Electrodynamic Characteristics of Patch Antenna

The paper presents the results of numerical modeling of the electrodynamic characteristics of a Vivaldi type patch antenna based on a circular disk resonator. The modeling was carried out using the semi-open resonator model by the finite element method (FEM) implemented in the HFFS package. The antenna was fed using a coplanar line segment. The antenna elements were placed over a grounded plane. The influence of design parameters and the function determining the curvature of the exponentially expanding slot discontinuity on the frequency, energy and polarization characteristics was investigated. It was established that with a certain selection of variable parameters, such an antenna can be matched with external circuits in the range from 7.03 GHz to 20 GHz with a level of VSWR values not exceeding 1.92. In the amplitude-frequency characteristic, fairly wide frequency bands with almost perfect matching are observed. The choice of the type of excitation element in the form of a section of the coplanar line made it possible to exclude additional elements inherent in Vivaldi antennas, namely, a section of the auxiliary strip line and a balancing resonator. This kind of antenna allows to form radiation patterns of various shapes from single-sided to cosecant quadrate. At the same time, in some intervals of observation angles, the formed fields turn out to be elliptically polarized with an ellipticity coefficient close to unity. The combination of the obtained results makes it possible to predict the use of this kind of antennas for operation with broadband signals.

A Novel Gain-Enhanced Miniaturized and Lightweight Vivaldi Antenna

A Novel Gain-Enhanced Miniaturized and Lightweight Vivaldi Antenna

Miniaturized Ultrawideband Circularly Polarized Antenna With Folded Arms Inspired by the Conventional Vivaldi Antenna

A method to reduce the volume of a circularly polarized Vivaldi-inspired antenna array by bending radiation arms is proposed in this paper. Two orthogonal Vivaldi elements form a cross-shaped configuration by rotating sequentially. For miniaturization and impedance match, two arms of the Vivaldi element are bent in opposite directions and then a folded cross-structure antenna is excited by a wideband feeding network with a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$90^{\circ }$</tex-math></inline-formula> phase difference. Forty copper columns were mounted evenly along the circumference on the ground, which can enhance mid frequencies gain. To validate results, the designed antenna is manufactured and measured, which depicts a wide impedance bandwidth (IBW) of 110.4% (1.59-5.51GHz) and an axial ratio bandwidth (ARBW) of 111.4% (1.55-5.45GHz). Moreover, the antenna can contribute a stable gain in the 4G LTE band and a high gain in 5G new radio bands (n77, n78, n79) with compact size. And it achieves a peak gain of 6.6dBic at 3.55GHz. Compared with other similar designs, the proposed antenna owns good performance while being greatly miniaturized, and its volume is only 0.21 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\lambda }_{l}$</tex-math></inline-formula> × 0.21 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\lambda }_{l}$</tex-math></inline-formula> × 0.11 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\lambda }_{l}$</tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\lambda }_{l}$</tex-math></inline-formula> is the free-space wavelength at 1.59GHz).

Design, Implementation, and Characterization of a Signal Acquisition Chain for SADino: The Precursor of the Italian Low-Frequency Telescope Named the Sardinia Aperture Array Demonstrator (SAAD).

Low-frequency aperture arrays represent sensitive instruments to detect signals from radio astronomic sources situated in the universe. In Italy, the Sardinia Aperture Array Demonstrator (SAAD) consists of an ongoing project of the Italian National Institute for Astrophysics (INAF) aimed to install an aperture array constituted of 128 dual-polarized Vivaldi antennas at the Sardinia Radio Telescope (SRT) site. The originally envisaged 128 elements of SAAD were re-scoped to the 16 elements of its precursor named SADino, with the aim to quickly test the system with a digital beam-former based on the Italian Tile Processing Module (iTPM) digital back-end. A preliminary measurements campaign of radio frequency interference (RFI) was performed to survey the less contaminated spectral region. The results of these measurements permitted the establishment of the technical requirements for receiving a chain for the SADino telescope. In this paper, the design, implementation, and characterization of this signal acquisition chain are proposed. The operative frequency window of SAAD and its precursor, SADino, sweeps from 260 MHz to 420 MHz, which appears very attractive for radio astronomy applications and radar observation in space and surveillance awareness (SSA) activities.

Electromagnetic near-field focusing based on metasurfaces

Near-field electromagnetic focusing has become a hot research topic due to its high application value in wireless transmission, wireless sensing, biomedicine, and radio frequency identification. In this paper, anisotropic metasurfaces have been proposed to manipulate the phase of the electromagnetic (EM) wave for obtaining EM near-field focusing. Under orthogonal linearly polarized incidence, dual focus functions can be realized independently for polarization multiplexing on the metasurfaces. Meanwhile, Single focus and multi focus with different energy distributions and focal position is obtained by the proposed metasurfaces. By using the Vivaldi antenna as the feed source positioning at the focal of the metasurfaces, a lens antenna with high gain is obtained with circularly polarized far-field mode and broadband characteristics. Due to the unique advantages of metasurfaces in modulating the phase distribution of EM waves, the proposed method may pave a new way for EM focusing application.

Antipodal Vivaldi Antenna with Star Trek insignia-based side slot edge for ultra-wideband applications

This article presents a Vivaldi Antipodal Antenna (AVA) with lens and radiating side cavities based on the Star Trek insignia, called Star Trek Side Edge Radiation (STSER-AVA). The objective was to improve parameters to make the radiation of the proposed antenna more directive. To this aim, the development is focused on reducing the squint of the central radiation beam and the side lobe level (SLL), as well as increasing the gain compared to a Conventional AVA. To achieve the objective, using an optimized design. The proposed antenna with or without a lens reached the target with a squint of -2.0 degrees, at 3.90 GHz the antenna with a lens achieved better gain (9.42 dB), but with a greater reduction in SLL of -10.73 dB compared to the lens less antenna. The results were obtained with computational electromagnetic simulations and experimental measurements.

Multibeam digital metasurface reflectarray antenna for 5G millimeter wave applications

AbstractA phase‐graded multibeam high gain digital metasurface reflector array (DMSRA) antenna for 5G millimeter wave communication is proposed in this letter. The DMSRA unit‐cell element is composed of a dipole loaded with endstubs. The variation of load across the diploe manipulates the reflection phase response of the incoming electromagnetic wave. A discretized phase state of 0° and 180° is obtained for an optimized loaded dipole. The phase states mimic the binary meta bit‐0 and meta bit‐1. The metabits are distributed along the reflecting surface using a digital coding sequence to form multiple beams in the desired direction. A coding sequence of 010101… is employed to design a two‐dimensional phase‐graded metasurface to generate a four‐beam radiation pattern. The designed digital metasurface reflectarray antenna of dimensions is fabricated and measured to validate the performance. The DMSRA is excited by an antipodal Vivaldi antenna positioned at an optimized focal point of 28 mm. The measured results show a four‐beam radiation pattern obtained over the frequency range of 27.5–28.5 GHz along azimuthal and elevation planes, with a peak beam gain of 10.5 dBi at 28 GHz.

A Compact Low Frequency Vivaldi Antenna for Ground Penetrating Radar

A Compact Low Frequency Vivaldi Antenna for Ground Penetrating Radar

Wideband Antennas of Passive Seekers for Anti Radiation Missiles

Suppression of Enemy Air Defence (SEAD) is a fundamental element of Air Power application by means of in protecting friendly air attackers and destroying the enemy’s ability to defend against air attack. Most of the SEAD operation even today relies on Anti-radiation missile (ARM) which is an air-to-surface tactical missile designed to detect, seek, attack and destroy opponent’s radar. Passive seeker of ARM is a miniaturized ESM receiver which is capable of extracting the necessary angular data from the enemy radar emissions. Single head passive seeker covering wide frequency range from L to Ku band is the preferred choice. Wideband antennas have been designed and utilized for Direction Finding applications of ESM/ELINT receivers for ground, air and ship borne platforms. Unlike these platforms, there are several restrictions for passive seeker based compact ESM receiver for missile borne platform specially air to surface missile where lesser diameter is one of the preferred design parameter. This review paper mainly discusses the existing wideband antennas such as spiral, log-periodic, printed circuit vivaldi and all-metal vivaldi antennas and the comparison of their various parameters for passive seeker. The paper also suggests their suitability with respect to their placement on the missile for three configurations: concealed inside the radome, flush-mounted and conformal antenna based. The paper also brought about the specific test facility required for testing and evaluation of passive seeker to characterize it with missile radome which is the most challenging and time consuming task. Among the three passive seeker configuration discussed, conformal antenna based passive seeker using all-metal Vivaldi is the best option avoiding radome aberration correction which is being utilized in the present third generations of ARM. The second commonly and established passive seeker configuration is concealed inside the radome using spiral antennas where handling radome aberration correction is a limitation.