Wide-angle Scanning Phased Array Research Articles

Wide-Angle Scanning Low Profile Phased Array Antenna Based on a Novel Magnetic Dipole

A novel microstrip magnetic dipole antenna that can be applied to wide-angle scanning phased array antennas in both E- and H-planes is proposed. The proposed antenna has a low profile of $0.03 {\lambda }_{0}$ ( $ {\lambda }_{0}$ denotes the free-space wavelength corresponding to the center operating frequency), and a compact size of $0.32 {\lambda }_{0} \times 0.31 {\lambda }_{0}$ . The half-power beamwidth of the proposed antenna with an infinite ground is about 180° in the E-plane and 85° in the H-plane, which has a large potential for wide-angle scanning phased array. When it is applied to phased array antennas, the scanning coverage is wide. The proposed planar phased arrays are fabricated and experimentally verified. The measured results show that the main beam can scan from −76° to 76° with 3-dB gain fluctuation in the E-plane and from −64° to 64° in the H-plane.

A Wide-Angle Scanning and Low Sidelobe Level Microstrip Phased Array Based on Genetic Algorithm Optimization

In order to obtain a wide-angle scanning and low sidelobe level (SLL) microstrip phased array with a finite metal ground, a novel microstrip phased array based on microstrip magnetic dipole is presented in this communication. Microstrip magnetic dipoles are employed as the driven elements in the phased array. Meanwhile, coupling patches are embedded between the adjacent driven elements, and coupling energy is transferred between driven elements by the coupling patches. Strong coupling has been constructed between elements as the driven element spacing is only about ${0}.\text{35}\; {\lambda}$ . With the influence of adjacent elements, the 3-dB beamwidth (BW) of each active element can reach over $\pm \text{80}^\circ $ in the elevation plane. From simulation and measurement, the main lobe scanning ranges of an 8-element and a 16-element phased arrays can both extend over $\pm \text{80}^\circ $ in the elevation plane with a gain fluctuation less than 3 dB. Furthermore, in order to keep the SLL low in the scanning, especially at the low elevation angles, genetic algorithm (GA) has been used, and the SLL has been decreased to the value of $- \text{9}\;\text{dB}$ in the full scanning range of $\pm \text{77}^\circ $ for the eight-element array.

Improving the Performance of Wide-Angle Scanning Array Antenna With a High-Impedance Periodic Structure

In this letter, the performance of wide-angle scanning phased array is analyzed. A high-impedance periodic structure (HIPS) is applied to improve radiation pattern of the antenna element in an array. The working mechanism of HIPS array is investigated. The structure could improve the surface-wave and the broad-beam radiation performance of the individual antenna element as well as the wide scan performance of the phased array. By the comparison to the metal ground plane, the gain of the array antenna is improved approximately 4.5 dB when the main beam scans at ±60°. A nine-element array antenna with a periodic structure is fabricated and measured. The measured results of the array coincide with the simulated results.

Wide-Angle Scanning Phased Array Using an Efficient Decoupling Network

The active impedance of each element in a phased array changes substantially with scan angle due to mutual coupling. Therefore, a key challenge in the design of wide-angle scanning phased array is to achieve wide-angle impedance matching (WAIM). In this communication, an efficient decoupling network is developed to reduce the mutual coupling between adjacent elements for this purpose. A complete scattering matrix analysis of the decoupling network is given and the design procedure is summarized. A ${1} \times {16}$ linear microstrip phased array has been designed and fabricated for experimental verification. Good agreement is obtained between measured and simulated results. The measured mutual coupling between adjacent elements is reduced to lower than $- {35}\; \text{dB}$ at the center frequency. Due to the reduced mutual coupling, the array can experimentally scan to 66° with a gain reduction of only 3.04 dB.

Broad beamwidth stacked patch antenna with wide circularly polarised bandwidth

A broad beamwidth stacked patch antenna with wide circularly polarised (CP) bandwidth is presented. The proposed antenna consists of a stacked structure with a rectangular shell under its ground structure to obtain CP characteristics and wide beamwidth. The radiation quality is excellent over the entire upper hemisphere. The 3 dB beamwidth of the proposed antenna on 2.4 GHz is larger than 140°. Moreover, the CP bandwidth, determined from the 3 dB axial ratio, is found to be about 240 MHz. CP bandwidth of 10.2% and the impedance bandwidth of 52.8% centred on 2.4 GHz are obtained. The proposed antenna is a good candidate for wide angle scanning phased arrays.

Small aperture evanescent‐mode waveguide antenna matched using distributed coupled resonators

Presented is a design methodology which permits the application of distributed coupled resonator bandpass filter principles to form wideband small-aperture evanescent-mode waveguide antenna designs. This approach permits matching of the complex antenna aperture admittance of an evanescent-mode open-ended waveguide to a real impedance generator, and thereby to a coaxial feed probe. A simulated reflection coefficient of <; - 10 dB was obtained over a bandwidth of 20%, from 2.0-2.45 GHz, in a 2.58 GHz cutoff waveguide. Dielectric-filled propagating waveguide and air-filled evanescent-mode waveguide sections are used to form the resonators/coupling elements of the antenna's coupled resonator matching sections. Simulated realised gain variation from 3.4-5.0 dBi is observed across the bandwidth. The antenna's maximum aperture dimension is <; 0.47 λ 0 at the upper operating frequency and so it is suitable for use in a wide angle scanning phased array.

Applying Band-Pass Filter Techniques to the Design of Small-Aperture Evanescent-Mode Waveguide Antennas

A design methodology is presented which applies band-pass filter principles to form wideband small-aperture evanescent-mode waveguide antenna designs. This approach permits matching of the complex antenna aperture admittance of an evanescent-mode open-ended waveguide to a real impedance generator, and thereby to an SMA coaxial feeding probe. A reflection coefficient of less than -10 dB was obtained over a measured bandwidth of 15%, from 2.30-2.68 GHz, in 2.72 GHz cutoff waveguide. Capacitive posts and evanescent-mode waveguide sections are used to form the resonators/coupling elements of the antenna's filtering sections. Measured realised gain variation from 3.5-4.7 dBi is observed across the bandwidth. The antenna's maximum aperture dimension is <; 0.5λ0 at the upper frequency in the bandwidth and so it is suitable for use in a wide angle scanning phased array.

Increased Bandwidth Evanescent Open-Ended Waveguide Antenna Design Using the Imaginary Smith Chart

We present a novel antenna matching technique that uses the Imaginary Smith Chart to permit wideband matching of an evanescent open-ended waveguide antenna using a dielectric sheet air-spaced from the aperture. The fabricated antenna design is demonstrated to have a measured bandwidth of 24%, from 2.13–2.7 GHz, for reflection coefficient <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\qquad{&lt;} -\!\!10~{\rm dB}$</tex></formula> , with 2.725 GHz waveguide cutoff. The antenna's maximum aperture dimension is <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${&lt; 0.5}\lambda_{0}$</tex></formula> at the upper frequency in the bandwidth and so it is suitable for use in a wide angle scanning phased array.