Performance Improvement in the Design of Broad-Beam Microstrip Reflectarray (original) (raw)

Broad-beam microstrip reflectarray using Gaussian backscatter function

IET Seminar Digests, 2007

This is a theoretical and experimental study of microstrip reflectarray useable in wireless local area networks (WLAN). The effectiveness of reducing the unit cell size of microstrip reflectarray which is duplicated the same radiating aperture as quadratic backscatter was investigated. A reflectarray with variable element sizes and reduced grid spacing have been designed at 10 GHz. For a given number of elements, it is shown that increased gain can be attainted for reduced unit cell size with no significant change in array size. To confirm the validity of this approach, an X-band antenna prototype was designed and developed. It was experimentally tested and showed good performance characteristics.

Design and Performance Improvement of Broad-Beam Microstrip Reflectarray

This paper presents the design and the effectiveness of reducing the unit cell size of microstrip reflectarray which is duplicated the same radiating aperture as quadratic backscatter. A reflectarrays with variable element sizes and reduced grid spacing have been designed at 10 GHz. For a given number of elements, it is shown that increased gain can be attainted for reduced unit cell size with no significant change in array size.

Optimum Design of Broad-Beam Microstrip Reflectarray

2007

The reflectarray's elements arrangement for generating an arbitrary phase distribution in the antenna aperture and thus a wide beamwidth of far field pattern are presented. The desired phase delay of reflectarray elements, which are duplicated the same radiating aperture as parabolic backscatters, are determined on the construction of the curvature of a shaped backscatter surface with the help of Snell's law for beam forming to cover a broad area. The method of moment (MoM) and the infinite-array are applied to calculate reflection phase characteristic. The optimized feed distance is calculated from the aperture efficiency with considering feed blockage efficiency and has investigated the influence of the feed position on the -3 dB beamwidth and gain performance. Having confirmed the validity of this approach, the X-band antenna prototype is designed and developed. This reflectarray is tested experimentally and shows good performance.

Design of broad-beam microstrip reflectarray

WSEAS Transactions on Communications

The reflectarray's elements arrangement for generating an arbitrary phase distribution in the antenna aperture and thus a wide beamwidth of the far field pattern is presented. The desired phase delay of reflectarray elements, which duplicated the same radiating aperture as backscatters, is determined on the construction of the curvature of a shaped backscatter surface with the help of Snell's law for beam forming to cover a broad area. The Method of Moments (MoM) and the infinite-array are applied to calculate reflection phase characteristics. The phase and radiation pattern synthesis method for microstrip reflectarray that has to illuminate a predefined circular area are presented by using a variety of discretization of elementary geometrical functions such as, triangular, quadratic, circular, gaussian, cosine, squared cosine, and parabolic distributions. These backscatter functions are discussed in terms of merits and demerits to find appropriate radiation characteristics ...

Investigation into Bandwidth Limitations of Microstrip Reflectarrays

2008

The paper describes theoretical investigations into the bandwidth limitations of a microstrip reflectarray which uses variable size antenna elements for its phasing. Three main factors limiting the bandwidth are considered. The first one is related to the phase compensation that is required to convert a spherical wavefront launched by the feed into a planar wavefront. The second one is linked to the limited phase range of typical microstrip antenna elements. The third one is related to the match between the required phase as a function of frequency and the fixed size elements' phase characteristics. The three factors are responsible for the reflectarray phasing errors that reduce its gain as the frequency departs from the centre frequency. It is shown that the first factor puts an upper limit to the reflectarray operational bandwidth, while the second one has a less profound impact. The third factor is influenced by choice of the element's shape. It is shown that circular and square patches offer better match than printed dipoles to the required phase slopes.

Designing Wideband Microstrip Reflectarrays for 10 GHz

European Journal of Science and Technology, 2022

This paper presents two microstrip reflectarray designs based on variable size unit cells for 10 GHz. One design uses a 3-layer unit cell with polygon shaped patch and the other uses a unit cell with 1-layer square loop patch. Both arrays have a size of 10λ × 10λ at 10 GHz, can reflect the incoming wave as a high gain pencil beam in the desired direction of θ = 30°. Gains at 10 GHz are 23.6 dB and 26.1 dB for the 3-layer and one-layer structures, respectively. The multi-layer structure resulted in a wider gain banwdith. Simulation results show that the 3-dB gain bandwdith is about 22% for the 3-layer structure reflectarray, as compared to 12% for the one-layer structure.

Performance of Thinned Microstrip Reflectarrays

International Journal of Engineering and Technology, 2010

A reflectarray uses the phasing characteristics of microstrip patches, on its aperture, to direct the main beam in a desired direction. The geometry and dimensions of the microstrip patches are used to control these phasing characteristics. Normally grid arrangement of microstrip patches on reflectarray aperture is rectangular or circular grid. In order to reduce the number of microstrip patched on reflectarray aperture, a novel thinning concept is proposed here. This thinning of reflectarray is proposed in the form of a novel windmill shaped grid setting. Parameters such as gain, SLL, beamwidth and number of elements of this reflectarray are compared with reflectarray having conventional grid settings and are presented in this paper.

Analysis and design of passive and active microstrip reflectarrays

International Journal of Rf and Microwave Computer-aided Engineering, 2003

The design of reflectarrays is a complex and time-consuming process that very often relies on a trial-and-error approach. In this article, a simplified analysis based on a commercial simulator is proposed. This method, valid for both passive and active antennas, uses a simulator to characterize the single radiating cell and evaluates the contribution of the finite ground plane using physical optics approximation. The proposed design technique has been validated by comparing the simulated response of the single element with the experimentally retrieved phase of the active and passive cell. As a proof of the design concept's feasibility, two small reflectarrays, active and passive, have been prototyped and tested. The measured radiation patterns are presented and discussed.

Design and Analysis of Microstrip Reflectarray Antenna With Minkowski Shape Radiating Element

Progress In Electromagnetics Research B, 2010

This paper describes the design and analysis of a Microstrip Reflectarray Antenna (MRA) with Minkowski shape radiating element at frequency of 11 GHz. This structure has been analyzed and compared with the traditional reflectarray element (square element patch). It is found that this antenna array has lower sidelobe level (SLL) characteristic which is down to −25 dB. This MRA has maximum realized gain of 29.6 dB with half-power beamwidth (HPBW) of 3.7 • . The validation for the proposed MRA is done by comparing the simulated and measured E-plane radiation pattern. A very good agreement is found from the comparison between simulation and measurement.

Bandwidth Improvement of Reflectarray Antennas Using Closely Spaced Elements

Progress In Electromagnetics Research C, 2011

A bandwidth improvement method in reflectarray antennas by using closely space elements, i.e., unit-cell sizes smaller than λ/2, has been investigated both numerically and experimentally in this paper. A new definition of phase error has been introduced to analyze the broadband mechanism of closely spaced phasing elements. Through full wave EM simulations, it is revealed that closely spaced elements achieve a smaller phase error over the band. Based on these theoretical studies two Ka-band reflectarrays were fabricated and their performance was measured across the frequency range of 30 to 34 GHz. It is demonstrated that the reflectarray designed with closely spaced elements achieves a notable improvement in gain bandwidth performance.