Ultra-wideband Phased Array Research Articles

Low-profile dual-polarized ultra-wideband phased antenna array based on metasurface

This paper presents what we believe to be a novel design for tightly coupled antenna arrays aimed at addressing the challenges associated with low-profile designs and dual polarization in ultra-wideband applications. The design features an innovative dual-polarized dipole arrangement and employs a cross-arranged methodology to construct the tightly coupled broadband antenna array. This approach achieves a working bandwidth ranging from the C-band to the Ku-band while maintaining a low-profile design. By incorporating a metasurface onto the tightly coupled array, this design significantly extends the effective working bandwidth while enhancing radiation performance throughout the beam coverage range. A 400-element dual-polarized array with an integrated phased array system is designed, fabricated, and measured. The antenna array is capable of ±60∘ beam scanning, with a relative bandwidth of 100% and a profile height of 0.38 wavelengths (at 18 GHz). This dual-polarized shared-aperture broadband phased array antenna not only facilitates flexible polarization synthesis but also offers a working bandwidth suitable for diverse application scenarios. Additionally, the implementation of an aperture reuse design minimizes the required aperture area. Collectively, these advancements enhance the overall performance of contemporary communication and radar systems, highlighting substantial application potential.

Performance analysis of scanning gain for irregular ultra wideband phased array antennas based on subarrays

Performance analysis of scanning gain for irregular ultra wideband phased array antennas based on subarrays

An Ultrawideband Phased Array Based on Exponential Curve Modified Dipoles

An Ultrawideband Phased Array Based on Exponential Curve Modified Dipoles

An Ultrawideband Dual-Polarized Phased Array Antenna for Sub-3–GHz 5G Applications With a High Polarization Isolation

A dual-polarized ultra-wideband phased array antenna with a wide scanning range and high isolation polarization characteristics is presented in this paper. A tightly coupled dipole with an etched slot is proposed as the element antenna, which has a low active input impedance in a wideband and a wide scanning range. Thus, a simple feed strategy without requiring additional external matching networks and baluns could be adopted for the designed scheme. To obtain a large polarization isolation, a capacitively-loaded cross-shaped metallic wall is proposed. It is also helpful to improve the in-band matching by mitigating the bandwidth-limiting loop mode at lower frequencies and removing the undesirable common-mode resonance. As a demonstration, an array is designed with a 4.1:1 bandwidth (0.69-2.88 GHz) and an active VSWR < 3.4 while scanning up to ±45° in the E-, H-, and D-planes. Its polarization isolation is better than 45 dB at the broadside and 35 dB within most of the bandwidth when scanning to ±45° in the E-/H-planes. Its cross-polarization level is more than 51 dB at broadside and 40 dB in scanning up to ±45° in the E- and H- planes. A dual-polarized 8×8 array prototype (64 ports per polarization) is manufactured and evaluated. Results from the experiment demonstrate good agreement between the measurement and design. The designed antenna is scalable, has a high polarization isolation, a wide scanning range, an ultra-wide bandwidth, and a low cost.

Design of Ultra-Wideband Phased Array Applicator for Breast Cancer Hyperthermia Therapy.

Focused microwave-hyperthermia therapy has recently emerged as a key technology in the treatment of breast cancer due to non-invasive treatment. An applicator of a three-ring phased array consisting of ultra-wideband (UWB) microstrip antennas was designed for breast cancer therapy and operates at 0.915 GHz and 2.45 GHz. The proposed antenna has an ultra-wideband from 0.7 GHz to 5.5 GHz with resonant frequencies of 0.915 GHz and 2.45 GHz and dimensions of 15 × 43.5 × 1.575 mm3. The number of each ring was chosen to be 12 based on the SAR distribution and the performance indicators of tumor off-center focusing results for four different numbers of single-ring arrays. The homogeneous breast model is applied to a three-ring phased array consisting of 36 elements for focused simulation, and 1 cm3 and 2 cm3 tumors are placed in three different locations in the breast. The simulation results show that the proposed phased array has good performance and the capability to raise the temperature of different volumes of breast cancer above 42.5 °C after choosing a suitable operating frequency. The proposed applicator allows for precise treatment of tumors by selecting the appropriate operating frequency based on the size of the malignant tumor.

A Low-Profile and Wide-Angle Scanning Planar Ultrawideband Modular Antenna With Ultra-Thin Loading Window

Ultrawideband phased antenna array has been widely used in communications, radars and detection. However, the high profile and poor wide-angle scanning characteristics have always been the critical limitation for many available ultrawideband antenna applications. In this paper, an ultra-thin loading window (UTLW) is proposed to replace the wide-angle impedance matching (WAIM) superstrate in the planar ultrawideband modular antenna arrays (PUMA), and reduces the profile height greatly. The UTLW consists of two strips in parallel, and each strip is loaded with two resistors and one capacitor. Following the equivalent circuit model (ECM) of the PUMA, the resistance and capacitance are specially designed to make the complex impedance of the UTLW equal to the impedance introduced by the WAIM. A dual-polarized PUMA with an UTLW achieves 6-18 GHz impedance bandwidth with active VSWR≤2.6 for scanning up to 60° and active VSWR≤3 for scanning up to 70° in E/D/H plane. The profile height of the proposed PUMA is only less than 0.07λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>l</i></sub> , or, 0.24λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>h</i></sub> with reference to the typical Nyquist half-wavelength spacing frequency. A 20×20 prototype PUMA with the UTLW was fabricated and its measured results were found consistent with the simulation results.

Flat Luneberg lens based on a printed circuit with curved conductors

The use of a printed Luneberg lens is promising for powering ultra-wideband phased array antennas with full-azimuth scanning. This article describes in detail the model for constructing a flat Luneberg lens based on a printed circuit with curved conductors. A certain pattern(pattern) with a relative permittivity er ≈ 1 was etched on the copper-coated substrate. This was done in order to realize the value of the refractive index. By printing a grid of intersecting conducting lines, a refractive index of 2was achieved in the center of the lens. The diameter of the Luneburg lens antenna was chosen to be 28.6 cm, which corresponds to 12,4l0 (l0 is the wavelength of free space) to achieve a half-power beam width of ≈ 5° at an estimated frequency of up to 20 GHz. Since the design of the Luneberg lens is based on geometric optics, the lens diameter must be a multiple of the wavelength to limit diffraction effects. Operating frequencies up to 20 GHz were selected. The lens was sampled into single cells. If the unit cell size is small enough, the lens can be described as a medium with a certain effective refractive index. As a result, this propagation theory can be used for lens design. The substrate used for the lens was 1 mm thick, the material used was Rohacell 31HF, which has a permittivity of 1,046 and a loss tangent of tg(d) = 0,002.

Review on Ultra-Wideband Phased Array Antennas

Ultra-wideband (UWB) phased array antennas are essential for radar, communication, and Electronic Warfare (EW) applications. Systems can operate over wide-band coverage. The high gain systems require wide-band, wide-angle scanning, good radiation pattern, and return loss over a multi-octave bandwidth. This review discusses the problems present in the UWB phased array system, which include mutual coupling, grating lobe rejection, active return loss, gain fluctuation with scanning, and multiple beam generation. In this, the aperture size of the array is limited by the overall gain requirement of the system. On the other hand, low gain systems require a wide-band with a good radiation pattern and axial ratio. Here the matching over wide-band is simpler as it depends on broadband balun configuration. This system has limited bandwidth over scan angles. These antennas are more preferred as wearable antennas in communication applications. This paper mainly discusses the existing UWB phased array antennas such as Vivaldi Arrays, All-metal Arrays, Spiral Arrays, Sinuous Arrays, and Coupled Arrays. This review paper presents a correct direction for selecting the type of antenna in terms of impedance bandwidth, gain, and materials influencing antenna performance, suited for different applications.

Ultra-Wideband Endfire Long-Slot-Excited Phased Array for Millimeter-Wave Applications

An ultra-wideband phased array with endfire radiation is proposed for millimeter-wave (mm-wave) applications. This array consists of a linear long slot array (LSA) source and a transverse-electromagnetic (TEM) horn radiator. For each unit, a Γ-shaped probe based on a substrate integrated coaxial line (SICL) is adopted to generate a primary slot source. Then, the slot flares in the E-plane with an exponential profile to form a horn unit. The antenna unit is studied with periodical boundaries (PBs) in simulation and operates from 15.4 to 46.4 GHz with active standing wave ratio (SWR) <; 3 for a scan angle of up to 45° in H-plane. To verify the design concept, two 1×16 finite arrays, Array-1 for 0° scan and Array-2 for 45° scan, are fabricated and tested. Over the operating band of 15.4-46.4 GHz, both arrays obtain good impedance matching in measurements with SWR <; 2.3. The measured gain varies from 11.8 to 19.1 dBi for Array-1 and from 10 to 16.9 dBi for Array-2 within 16-40 GHz. Besides, Array-2 exhibits a scan angle of 48° and an average scan loss of 2.4 dB. Moreover, both arrays achieve a radiation efficiency exceeding 73% because of employing the low-loss SICL feed network.

Triangular grid interconnected crossed rings antenna for large‐scale ultra‐wideband dual‐polarised arrays

An ultra-wideband phased array antenna using interconnected elements arranged in triangular lattices is investigated. The basic unit cell of the array is a dual orthogonal crossed ring structure. Each element is interconnected to its neighbour using capacitive loading. The ring structure on a planar surface produces broad frequency bandwidth with wide scan angles. Unlike other three-dimensional elements such as Vivaldi antennas, the interconnected crossed ring elements can be readily configured on a triangular grid. As is well known from narrow band arrays, a triangular grid allows reduction in the total number of elements needed for a given performance compared to a square grid. The array presented here applies the triangular grid to a broadband planar structure to reduce the total number of elements required by 13% while the electromagnetic behaviour of the array is essentially maintained. An array prototype of the design has been manufactured and tested. The performance is compared to the associated array with a regular square lattice. The proposed triangular grid structure is shown to be an effective solution for applications where a minimum number of elements is required for large-scale broadband dual-polarised antenna arrays.

Applying of Luneburg lens for multi‐beam TEM‐horn antenna

Here, a multi-beam TEM-horn antenna with beam direction is proposed. Presented construction allows obtaining scanning beam and complicated antenna patterns, thus it can be used as substitute of ultra-wideband phased array antennas.

Ultra-Wideband Phased Array for Millimeter-Wave ISM and 5G Bands, Realized in PCB

In this paper, we present the design, fabrication, and measurement of an ultra-wideband phased array antenna, with continuous coverage of all six allocated fifth generation and industrial, scientific, medical bands in the millimeter-wave spectrum. Of importance is that the complete array is co-fabricated as a single printed circuit board using commercial processes, implying a significant reduction in cost over previous microfabrication-based designs. The design is demonstrated in simulation to operate across 24–72 GHz with VSWR $3\times 3$ array prototype, which shows close agreement to the simulated values.

Optically Driven Ultrawideband Phased Array With an Optical Interleaving Feed Network

A novel optically driven ultrawideband phased array is presented. In the array, two coherent optical signals mixing at photodiodes produce RF signals that are tunable over an ultra-wide bandwidth. An optical interleaving feed network is used to drive the array, which is capable of mitigating phase drift due to acoustic vibration and maintaining phase fidelity. In addition, excess noises in the system are analyzed and found to be responsible for spurious beams. The excess noise can be suppressed by optimizing polarization states of optical signals in polarization-maintaining (PM) fibers. Accordingly, the sensitivity can be significantly increased. In the end, the concept is proven by demonstrating experimental results from a 1 × 2 array consisting of two wideband Vivaldi antennas.

The Planar Ultrawideband Modular Antenna (PUMA) Array

A fully planar ultrawideband phased array with wide scan and low cross-polarization performance is introduced. The array is based on Munk's implementation of the current sheet concept, but it employs a novel feeding scheme for the tightly coupled horizontal dipoles that enables simple PCB fabrication. This feeding eliminates the need for “cable organizers” and external baluns, and when combined with dual-offset dual-polarized lattice arrangements the array can be implemented in a modular, tile-based fashion. Simple physical explanations and circuit models are derived to explain the array's operation and guide the design process. The theory and insights are subsequently used to design an exemplary dual-polarized infinite array with 5:1 bandwidth and VSWR <; 2.1 at broadside, and cross-polarization ≈ -15 dB out to θ = 45° in the D- plane.

A Double Rhombus Antenna Fed by 180$^{\circ}$ Phase Shifter for Ultrawideband Phased Array Applications

A double rhombus antenna fed through a microstrip 180deg phase shifter is presented. The 180deg phase shifter is a novel design of microstrip-to-coplanar waveguide (CPW)-to-microstrip transition. The proposed phase shifter is obtained without changing the layer of the second microstrip line for an easy embedding into the feedline. Via holes are used to transfer the current from the top to the bottom substrate layer and vice versa. The antenna with the phase shifter is operating in a wide bandwidth from 5.7 and 18.6 GHz (106%), and provides stable endfire radiation patterns. This design is tested in a modified two-element array configuration and proved to have a wide usable bandwidth.

Electronic beam-steering design for UWB phased array

A novel electronic beam-steering subsystem providing true time-delay technique has been developed for an ultra-wideband (UWB) phased array. The relative time delay for phase interpolation is variable from 100 to 500 ps. Scanned angles from 9deg to 59deg were achieved. The chip is designed using 0.25-mum CMOS silicon operating at 2.5 V, and its outputs are matched to 50 Omega loads using bipolar buffers. The design of the beam-steering architecture will be presented. The measured results of the chip and the UWB phased array, including radiation patterns and pulse-width distortions, will be discussed