Balanced Antenna Research Articles

A high gain microwave and millimeter-wave-based balanced antipodal Vivaldi antenna with a parasitic patch and a half-spherical shaped dielectric lens

This paper presented the design and performance analysis of a high-gain balanced antipodal Vivaldi antenna (BAVA) integrated with a parasitic patch and a half-spherical shaped dielectric lens, specifically designed for microwave and millimeter-wave applications. Constructed with a Teflon substrate (εr = 2.1, tanδ = 0.0002) and energized by a 50-ohm microstrip feedline, the innovative design incorporated a parasitic patch and three different types of dielectric lenses: half-circular, conical, and half-spherical shaped. The half-spherical dielectric lens significantly enhanced performance, achieving a gain of 20.54 dB, side lobe level (SLL) of -18.15 dB, and a maximum beam squint of 1.59 degrees. Additionally, it exhibited a 98% radiation efficiency, a front-to-back ratio of 31.75 dB, and a half-power beamwidth (HPBW) of 6.7 degrees. The incorporation of a parasitic patch and a half-spherical shaped dielectric lens enhanced the antenna's performance. Comparative analysis with existing antennas underscored the superiority of the proposed design, positioning it as a promising solution for microwave and millimeter-wave communication systems, radar, and sensing applications.

Inkjet‐printed capacitively loaded Marchand baluns with enhanced fractional bandwidths

AbstractA comprehensive design methodology for the realization of ultra‐wideband and highly miniaturized capacitively loaded Marchand baluns (MBs), suitable for integration into balanced antenna systems is presented. A design technique to maximize the fractional bandwidth (FBW) for a given manufacturing process is demonstrated for the first time. Furthermore, a novel MB integration scheme using broadside‐coupled lines and 3D vertically integrated capacitors in a two‐material inkjet printing process is uniquely proposed. The concept has been experimentally validated within the S and C bands. It exhibits a footprint of 0.128 × 0.098 λg2, centre frequency of 4.4 GHz, and FBW of 121%. Its power loss, phase imbalance and amplitude imbalance were measured between 0.8 and 2.2 dB, 3 ± 2°, and 0.4 ± 0.4 dB, respectively.

Super-wideband fractal antenna of two-arm structure with broadband balun

ABSTRACT A balanced two-arm antenna has been proposed for super-wideband (SWB) operation to work efficiently over the frequency range (2.95 − 34 GHz ). The antenna proposed for SWB operation can be considered as composed of two main parts. The first part is the radiating surface of the antenna and is composed of two-arms leading to a balanced antenna structure. For wideband operation, each arm has a double-fractal (angular/radial) structure. The second part of the antenna structure is the wideband feeding balun that is responsible for realising maximum power transfer and impedance matching while feeding the balanced radiating two-arm structure from the conventional unbalanced coaxial line. A prototype has been fabricated for experimental characterisation of the proposed antenna. Both the simulation results and the experimental measurements come in good agreement with each other showing that the proposed antenna can be good candidate for many super-wideband applications of future generations of mobile communications. The proposed antenna has overall dimensions of 40.0 mm × 21.0 mm × 1.5 mm . It is shown by simulation and measurement that the proposed antenna has %BW of 168 % , RBW of 11.5 : 1 , and BDR of 2015 . The maximum gain ranges between 2.3 and 6.2 dBi. The radiation efficiency is greater than 98% over the frequency range ( 2 − 24 GHz ) and is greater than 85% over the frequency range ( 24 − 34 GHz ).

Design of a New Balanced Side Slotted Vivaldi Antenna with Director using Genetic Algorithm

Generally, side slotting and directional techniques can improve the performance of a conventional Vivaldi antenna (CVA), but the optimal structure and distribution of slots and directors may be irregular or even complex, requiring significant manual effort, thus limiting the design possibilities. In this paper, a genetic algorithm (GA) is introduced to assist in designing and optimizing a new type of balanced side slotted Vivaldi antenna with director (SSVAD). The methods of artificial intelligence make the process of searching for the optimal structure of such a multi-objective and multi-dimensional problem simpler and more diverse. The GA-generated SSVAD antenna consists of a CVA and 34 slots with varying lengths, as well as 5 metal strips. It has a compact size of 38.2×49×0.8 mm3 (or 0.32λL×0.41λL×0.007λL, where λL is the lowest operating frequency of 2.48 GHz). The measured results show that the antenna has a peak gain >0 dBi over 2.48-10.88 GHz and >5 dBi over 4.6-10.88 GHz with S11<-10 dB standard, and exhibits directional characteristics at most of the operating frequencies. Since the measured results are basically consistent with the simulation ones, the effectiveness of the designed scheme has been proven.

A Balanced Filtering Antenna Array With High Gain, Steep Selectivity, and Multiradiation Nulls Parallel-Fed by Differential Broadband Network

A Balanced Filtering Antenna Array With High Gain, Steep Selectivity, and Multiradiation Nulls Parallel-Fed by Differential Broadband Network

Microwave Antenna Design for Cardiovascular Applications: A Comparison Between a Balanced and Unbalanced Microwave Ablation Antenna

Microwave Antenna Design for Cardiovascular Applications: A Comparison Between a Balanced and Unbalanced Microwave Ablation Antenna

On Autonomous Phase Balancing of the Coplanar Stripline as a Feedline for a Quasi-Yagi Antenna

This paper provides a clear demonstration that a coplanar stripline (CPS) as a balanced line can act to re-establish the phase balance in the presence of phase deviation from a 180° distance between two input signal lines connected to the CPS. A half-wave delay line splitter connected to a CPS works as a balun to feed a balanced antenna, such as a quasi-Yagi antenna. This type of balun structure has been widely used to feed balanced antennas with a frequency bandwidth of up to 60%. Nevertheless, no clear explanation has been given regarding how the broadband antennas could be implemented with this type of balun structure. In this paper, through 3D EM simulations and measurements, it is shown that the half-wave delay line splitter indeed only results in the 180° phase balance at one frequency, but the subsequently connected CPS acts to recover the phase balance between the signal lines. The CPS can recover the phase balance within a phase imbalance of ~π/3, which determines the usable bandwidth of this structure. For a demonstration, with a center frequency of 10 GHz, samples of the half-wave delay line splitter connected to a CPS are fabricated and measured.

The characteristic impedance calculation method of microstrip line and application in embroidered microstrip line

Presently, it is difficult to measure the characteristic impedance of embroidered microstrip line for its conductive anisotropy directly. The published work had proposed to use S-parameters to estimate the port impedance of a balanced dipole antenna, and it cannot be used to calculate the characteristic impedance of microstrip lines with one arm. Thus, it is still a problem on measuring and obtaining 50 Ω characteristic impedance of embroidered microstrip line. Therefore, taking the reflection coefficient as an intermediate variable, this work proposes to use return loss [Formula: see text] to derive the expression of the characteristic impedance of microstrip line. Combined theoretical calculation with experimental testing on characteristic impedance of the fabric-based microstrip line, the expression of the characteristic impedance was verified. Then, the expression of the characteristic impedance of microstrip line was used to calculate the characteristic impedance of embroidered microstrip line and determine its equivalent substrates. The results show that the fabric embroidered with a single-layer conductive strip is a part of its equivalent substrate, and the fabric embroidered with a double-layer conductive strip is not a part of its equivalent substrate.

Beam‐squint rectified balanced antipodal Vivaldi antenna with sliced fins and quarter‐wavelength labyrinth director

AbstractThis paper introduces a gain‐enhanced, beam‐squint rectified balanced antipodal Vivaldi antenna (BAVA) with symmetrically sliced fins and a novel square‐shaped metallic labyrinth director. The proposed antenna operates from 2 to 18 GHz with S11 less than −10 dB maintaining a fractional bandwidth of 160%, realizes 12.564 dBi as maximum gain at 18 GHz, and achieves greater than 3.415 dBi gain throughout the functioning band of frequency. Improvement of broadside gain by reconfiguration of current loops through symmetric slicing of radiating flares and beam‐squint correction using quarter‐wavelength labyrinth director are addressed by the proposed antenna. The maximum realized size of the antenna is 80 × 40 × 0.508 mm3. Consistent radiation patterns are observed at selected frequencies. Numerical evaluation with a full wave simulation tool and consequent experimental validation with a compact antenna test range is performed.

SICL-Fed Balanced Antipodal Dipole Antenna With Wideband Operation and Cross-Polarization Improvement at Millimeter-Wave Band

A substrate integrated coaxial line-fed balanced antipodal dipole antenna array is proposed for millimeter-wave (MMW) applications in this letter. Different from the traditional dual-armed dipole antenna, a balanced antipodal dipole element with three arms is proposed to improve the cross-polarization level by canceling the vertically polarized electric-field components. A cross-polarization level of less than −20 dB is achieved over the entire frequency band. Meanwhile, a gap is etched on each dipole arm to achieve dual-mode operation and broaden the impedance bandwidth of the dipole element, and an impedance bandwidth of more than 65% is obtained. By combining the proposed dipole elements with the unequal feeding network, a 1 × 8 dipole antenna array is designed, fabricated, and measured. The measured results show that the proposed dipole antenna array can achieve a wide −10 dB impedance bandwidth of more than 54% from 24.5 to 43 GHz, a sidelobe level of low than −18 dB in E-plane, and a cross-polarization level of low than −20 dB. With the merits of wide operating bandwidth, low cross-polarization level, low sidelobe level, low profile, and easy integration, the proposed antenna array is valuable to advanced MMW communication systems.

A multi‐port interconnected magneto‐electric dipole antenna array for 5G applications

A multi‐port interconnected magneto‐electric dipole antenna array for 5G applications

Modeling analysis of patch antenna efficiency considering impedance matching characteristics of cable feed end

The small size of patch antenna makes its application scenarios diverse, and its research is quite extensive. However, the calculation of the influence of the applied excitation source and operating band on the overall operation of the antenna is very complicated, and the related modeling is less. Therefore, a patch antenna model with dual input feed is constructed by COMSOL based on the finite element analysis method. After considering the reasonableness of the coaxial cable insulation medium setting, the geometry structure of the patch antenna with dual input end feeding is constructed. The balanced antenna uses two input feeds, so in the balanced system, the operational performance of the antenna is changed by adjusting the two input signal excitation, so the spatial electric field distribution of the patch antenna under different operating frequencies is explored by applying different external applied excitation sources. Finally, the electric field change law of patch antenna under different operating working conditions is compared and analyzed, and the way to analyze the antenna operating performance is summarized.

A UWB Low-Profile Hemispherical Array for Wide Angle Scanning

We report the first low-profile array on a doubly curved surface that supports wide angle electronic scanning and ultrawide bandwidth (7:1 ratio). The array elements are based on the balanced antipodal Vivaldi antenna (BAVA). The antennas are optimized for a good impedance match in an infinite planar array environment and are then deformed to fit along the surface of a hemisphere. The array is comprised of 104 linearly polarized BAVA elements arranged along a quadrilateral mesh on the surface of a 100 mm diameter hemisphere. The antennas and SMP connectors are 3-D printed out of titanium. The array has grating lobe-free operation at frequencies < 8 GHz. The array can also maintain relatively low sidelobe levels above 8 GHz compared with planar arrays because the aperiodicity of the hemispherical element locations reduces the magnitude of grating lobes. The simulated and measured realized gain is within 1 dB of the theoretical limit from 2.5–18 GHz and scan angles with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\theta \le {\mathrm {90}}^{\circ }$ </tex-math></inline-formula> except near 14 GHz where a resonance reduces the gain by 3 dB for some scan angles.

High power balanced TEM horn antenna for ultra wide band radiator

AbstractA balanced transverse electromagnetic (TEM) horn type antenna is designed and developed for a 120 kV, 66 Ω high power ultra wideband (UWB) radiator. This antenna consists of a coaxial to parallel plate unzipper BALUN followed by an exponentially tapered TEM horn structure. Analysis of this antenna in time and frequency domain is performed using CST Microwave Studio. This antenna is having a power handling capacity of 1000 MW, with percentage bandwidth of 167%. This antenna has a gain of ~10 dB at 1 GHz frequency. Return loss performance of better than −10 dB is observed in 150 MHz to 1 GHz frequency range. Effective radiation of short pulses (&lt;5 ns) with very fast rise time (300–500 ps) has been demonstrated using this high‐power antenna. Practical results at 220 MW power are presented in this article. Directional performance of this antenna is practically established through peak power patterns in horizontal and vertical plane.

Asymmetric meshed ground Balanced Antipodal Vivaldi Antenna with quarter-wavelength labyrinth director for ultrawideband microwave applications

This paper introduces a new compact Balanced Antipodal Vivaldi Antenna (BAVA) with asymmetrically meshed ground, square shaped metallic labyrinth and dual scale edge treatment. The proposed antenna operates from 4 GHz to 18 GHz with S11 less than −10 dB, 127.27% fractional bandwidth and realizes greater than 4.01 dBi gain throughout the functioning band of frequency and achieves a maximum of 13.46 dBi at 17 GHz. Group delay of less than 5 ns signatures are realized. Improvement of operating bandwidth through enhanced impedance matching by finely meshed pattern on the ground planes and containment of rate of change of deflection angle using quarter-wavelength labyrinth director are addressed by the proposed antenna. The maximum realized size of the antenna is 80 × 40 × 0.508mm3. In addition, consistent radiation patterns are observed at selected frequencies. Numerical analysis with a full wave simulation tool is performed to calculate the radiation characteristics of the antenna and are experimentally validated.

An 8 × 8 ultra‐wideband tightly coupled dipole active phased array

An 8 × 8 ultra-wideband tightly coupled dipole active phased array with 64 T/R modules is presented in this paper. The proposed active phased array with 64 T/R modules is able to operate over a 5:1 bandwidth (2.05 ~ 10.3 GHz) in receiving mode and 8 ~ 10 GHz in transmitting mode. The array utilized tightly coupled balanced antipodal dipole antenna elements, which exhibits excellent scanning performance (±60° in E plane, ±60° in D plane and ±45° in H plane) and low cross-polarization characteristic (<−28 dB at broadside). The tiled transmitting/receiving modules (T/R modules) can successfully control the amplitude and phase of the feeding signal in each active channel. Besides, the total gain of all channels in receiving mode and transmitting mode are 30 and 26.4 dB, respectively, which shows good performances in receiving and transmitting signals. A prototype of 16 × 16 antenna array is fabricated. The central 8 × 8 elements are active elements that are connected to 64 channels T/R module. The remaining elements are dummy elements that are connected to 50Ω loads to alleviate the edge effect. The measurements of central 8 × 8 elements are taken after the assembling of the antenna array and T/R modules. Good performances are achieved and the application potential of this phased array system is also validated.

Bent coplanar waveguide feeds for balanced planar antennas and arrays

Bent coplanar waveguide feeds for balanced planar antennas and arrays

A balanced filtering quasi‐Yagi antenna array with sharp roll‐off skirts and high common‐mode suppression

In this article, a balanced filtering antenna array with quasi-Yagi performance is presented. The proposed design is composed of a balanced-to-single-ended power division network, two bandpass filtering units and a linear quasi-Yagi array including four elements. A steep differential-mode (DM) passband frequency response is obtained by introducing the triple-mode folded cross stub-loaded resonators (FC-SLRs) in the power division network. The fractional bandwidth and center frequency can be controlled conveniently by adjusting the dimensions of FC-SLRs. Further, the design procedure is simplified due to the DM responses which are independent of the common-mode (CM) ones. The proposed antenna array with high gains, good CM rejections, and low cross-polarization levels is achieved. In addition, three radiation nulls are engendered on the sidebands to improve the selectivity. For demonstrating its feasibility, the balanced antenna prototype is fabricated and measured. The good performances of the proposed balanced filtering antenna array are observed.

2–18 GHz balanced antipodal Vivaldi conformal phased array antenna with resistive load and shorting posts

In this paper, a 2–18 GHz balanced antipodal Vivaldi conformal phased array antenna is proposed. Firstly, the conformal array achieves a low profile of 0.11λLow by using the tightly coupling mechanism. Here, the gap-induced element resonance (GIER) and the common mode resonance occur in the operating band, limiting the impedance bandwidth. Thus, the resistors are loaded to eliminate the GIER by suppressing the resonant current. Furthermore, the shorting posts are used to remove the common mode resonance by decreasing the resonant length. A transition structure between the stripline (SL) and the ground coplanar waveguide (GCPW) is designed to feed the antenna. The simulated results show that the array achieves a 9:1 bandwidth (2–18 GHz) for active VSWR <2.5 at broadside. Besides, the active VSWR is less than 2.5 for ±60° scanning in E-plane and 3.8 for ±45° scanning in H-plane. A 12 × 8 array prototype is fabricated and measured to validate the performance of the array. The measured results show a good agreement with the simulation.

Sixteen‐port dual band multiple‐input multiple‐output antenna array for 5G mobile terminal applications

A 16-port dual-band multiple-input multiple-output (MIMO) antenna array with high isolation is proposed. To obtain decent isolations, not only a high-isolated antenna block composed of dipole antenna and slot antenna is designed, but also the mutual coupling between blocks is analyzed and reduced. The isolations of better than 17 and 24.2 dB across the two operating bands are achieved by using orthogonal polarization, balanced antenna structure, and grounded stub. The proposed MIMO antenna array was fabricated and measured. The total efficiency is better than 54% and the envelope correlation coefficients are lower than 0.11. The proposed MIMO antenna array exhibits sufficiently good MIMO performance with the channel capacity up to 86.6 bps/Hz.