Design Of Reflectarray Antenna Research Articles

Millimeter Wave Beam Steering Reflectarray Antenna Based on Mechanical Rotation of Array

This work provides design and analysis of a beam steering reflectarray antenna, designed at 26 GHz, based on the mechanical rotation of the array. Unit cells based on circular ring elements are designed, and scattering parameter measurements have been carried out for obtaining progressive phase distribution. The unit cell measurements demonstrated a maximum reflection loss of 4 dB with a total phase range of almost 360°. Symmetricity of the array and the resonant elements has been exposed to steer the main beam by tilting the reflectarray at different angles. A beam steering range of more than ±60° has been demonstrated by varying the tilt angle from +30°to -30°. The designed 20 × 20 element array provided a maximum gain of 26.47 dB at 0° which reduced to 19.8 dB at 61.9° in the elevation plane. On the other hand, the reflectarray antenna demonstrated a maximum bandwidth of 13.1% with a minimum side lobe level of -25.9 dB.

The design of a wideband single-layer dual-band reflectarray antenna based on an optimized element

A design for a broadband single-layer dual-band reflectarray antenna is presented. A genetic algorithm is employed to design and optimize the element of the antenna. The basic idea to improve the bandwidth of the proposed antenna is based on increasing the range of the linear region of the phase response of the microstrip element. The definition of the fitness function plays an important role in the design process for the optimized unit cell. Three different unit cells with various fitness functions are proposed. Two reflectarrays with 185 elements were designed and simulated based on two different optimized cells. One of the simulated reflectarrays, containing the simpler cells, is fabricated. The designed reflectarrays exhibits a wider gain bandwidth compared with other reflectarray structures proposed in literature. The 3-dB gain bandwidth of the fabricated antenna in the X and Ku bands is 39 % and 44 %, respectively. The gain of the proposed antenna is 21.8 and 26.6 dB at 7.8 and 12.2 GHz, respectively. The proposed design procedure is flexible and could be used to design reflector array antennas with various and arbitrary properties.

Design and fabrication of a wideband reflectarray antenna in Ku and K bands

The purpose of this paper is design of a wide band single layer reflectarray antenna using a new broadband cell. The proposed cell consists of two parts. The first part is a circular patch and the second one is a ring with some additional stubs, which are attached to the patch and ring in a symmetrical form. The circular patch and ring elements are designed at frequencies of 20 GHz and 15 GHz respectively. In order to increase the reflectarray antenna bandwidth, at first the dimensions of the patch, ring and stubs are optimized to attain uniform phase response in the frequency range from 11 GHz to 20 GHz. Then an air layer is considered under the dielectric substrate. The reflectarray antenna is designed based on this optimized wideband unit cell. A wideband horn antenna is also designed as a feed antenna for the proposed reflectarray structure. The reflectarray antenna with horn are simulated. The 1 dB gain-bandwidth of 4.66 GHz is obtained (27.4% fractional bandwidth) in the frequency band of 14.72 GHz to19.38 GHz. Finally, the reflectarray antenna is fabricated and tested. It can be seen that there is a good agreement between simulation and measurement results.

Synthesis and Characteristic Evaluation of Convex Metallic Reflectarray Antennas to Radiate Relatively Orthogonal Multibeams

In this paper, we present the design of metallic reflectarray antennas consisting of convex nonresonant elements to radiate multiple beams with optimum radiation gains and relatively orthogonal overlapping. In particular, an antenna is realized at 38 GHz to provide sufficient gains and beam widths for simultaneous link-budget and radio coverage satisfaction in the applications of fifth-generation mobile communications. The pattern optimization employs the steepest decent method (SDM) to optimize the phases of reflecting elements for gain tradeoff. The SDM procedure is very efficient because relatively simple formulations of analysis in closed form are developed to subsequently update the phases in each iteration. This procedure avoids the cumbersome and numerous full-wave numerical simulations of scattering fields. Design examples and their radiation characteristics are presented to demonstrate the concepts and validate the feasibility.

An investigation of millimeter wave reflectarrays for small satellite platforms

This article reports two contributions related to reflectarray antenna design at millimeter waves (mm-waves). First, a closed form analytical formulation is provided for the prediction of reflection properties of square/rectangular mm-waves reflectarray unit cells based on various quality factors and the theory of waveguide coupled resonators. To ensure a high accuracy at mm-waves, the effects of fringing fields, surface waves, metal conductivity, and metal surface roughness are included in the analysis. This analysis program greatly facilitates the parametric studies of a unit cell's constituting parameters to converge on an optimum design solution. Secondly, the concept of phase quantization is proposed for a cost effective realization of mm-waves reflectarrays. The developed formulation in the first contribution was used to design two 3 bit phase quantized, single layer, 19 wavelength, passive reflectarrays at 60 GHz. The test results are compared with simulations and a very good agreement was observed. These findings are potentially useful for the realization of high gain antennas for mm-wave inter-satellite links in small satellite platforms.

Gain optimization for millimeter wave reflectarray antennas based on a phase gradient approach

This paper is concerned with reflectarray antenna design with multiple unit cells in order to enhance the gain at the design frequency, while keeping an acceptable bandwidth to work for 5-G mobile base station applications. The design is based on five unit cells. The design begins with an investigation of the phase responses of all unit cells. It is required to choose a unit cell that can span 360° with linear characteristics. Unfortunately, none of the unit cells has perfectly linear phase characteristics. Each of them has a limited linear phase region. The proposed reflectarray design method selects the most linear region from each phase curve for selecting the appropriate unit cell with the appropriate size for each required phase using a phase gradient approach. With this approach, piece-wise linear phase characteristics are adopted for the design of the reflectarray to enhance the gain at the design frequency.

Switching Between Unit Cells: A Tool to Break the Limits on the Performance of Reflectarray Antennas

For decades, the design of reflectarray antennas followed a unified strategy of selecting a certain unit cell for the whole design. After that, the dimensions or orientations of this unit cell are changed to achieve the required phase shift at each position on the reflectarray surface. This strategy requires a 360° span of the phase characteristics of the selected unit cell versus a control parameter. In addition, it requires maximal linearity of the phase characteristics of the unit cell. This paper considers a different and more flexible strategy for the design of reflectarrays. This strategy is based on switching between unit cells to make use of the regions of the characteristic phase curves of best linearity for each unit cell. With this strategy, we can use unit cells with similar polarization, and unit cells that do not span 360° in phase characteristics in the design process of the same reflectarray. The single criterion for switching between unit cells is the maximal linearity of the phase characteristics of the unit cell at the required phase. This strategy guarantees maximization of the gain, and minimization of the side-lobe level (SLL) at the design frequency. The proposed strategy is validated for the design of a reflectarray antenna to work at 28 GHz using five different unit cells for possible 5G applications. The simulation results reveal the feasibility of the proposed strategy for achieving high gain and low SLL at 28 GHz.

A Mechanically Reconfigurable Reflectarray With Slotted Patches of Tunable Height

Design of a C-band reconfigurable reflectarray antenna (RRA) is presented. The RRA element consists of a fixed upper patch and a tunable slotted patch. By mechanically controlling the height of the slotted patch, the RRA element has a phase shift range of 324° with small element loss. A prototype with 408 elements is designed and fabricated. The measurements show that the gain of the 20° scanned beam is 25.7 dB and the aperture efficiency is 48.6%. The large-angle beam-scanning capability of the RRA is also verified within ±60° angular range, and well-defined scanned beams are obtained with maximum scan gain loss of 3.4 dB.

Optimized Periodic MoM for the Analysis and Design of Dual Polarization Multilayered Reflectarray Antennas Made of Dipoles

A hybrid version of the Method of Moments (MoM) is applied to the analysis of the scattering of plane waves by periodic multilayered structures containing dipoles at two metallization levels. The MoM matrix entries involving basis functions (BFs) at different metallization levels are computed in the spectral domain as double infinite summations with fast exponential convergence. The MoM matrix entries involving BFs at the same metallization level are computed in the spatial domain as double integrals, which require low-order quadrature rules. The integrands are cross correlations between BFs times multilayered periodic Green’s functions (MPGFs). The cross correlations between BFs are obtained in terms of elliptic integrals of first and second kind. Also, the MPGFs are accurately interpolated in 4-D in terms of both the spatial variables and the angles of incidence. The hybrid MoM proposed is used in the design of dual polarization reflectarray antennas under the local periodicity assumption. Thanks to the 4-D interpolation of the MPGFs, which minimizes the total number of MPGFs that have to be computed per reflectarray element, the proposed hybrid MoM is shown to be around 15 times faster than the standard spectral domain MoM in the design of the antennas.

Design and analysis of dual U slot reflectarray antenna for X-band applications

A novel design of a dual frequency single layer reflectarray antenna is presented for X-band frequency applications. Dual U slots embedded on conventional rectangular microstrip reflectarray have been designed to attain a dual frequency operation. A detailed analysis of the effect on surface current distributions with the introduction of dual U slots is presented. Moreover a parametric study on the variation of significant dimensions of the design have been carried out and analysed thoroughly using a commercially available CST computer model. Proposed design configurations were fabricated above a 0.508 mm thick substrate of Rogers Duroid 5880. The dual U slot configuration offers a significant dual frequency behavior at 8.54 and 11.56 GHz with 10% bandwidth improvement of 47 and 56 MHz with a reflection loss of -4.54 and 4.11 dB respectively.

Equivalent Circuit Modeling for Reflectarrays Using Floquet Modal Expansion

The starting point in the design of reflectarray antennas is the derivation of the so-called S-curve, which maps changes in unit cell design parameters to the phase of the scattered field from the cell. In general, full-wave simulations are used to derive this curve, though recently a number of analytical techniques have emerged based on equivalent circuit models (ECMs). However, most ECMs are cumbersome to employ, either because they are too specialized or they depend on extraction of component values from supplementary simulations. This paper presents a fully analytical method for predicting the S-curve from dipole-like reflectarray elements based on an ECM derived from a Floquet modal expansion of a planar dipole. The model does not need supplementary simulations that can be used to predict the co-polarized reflection coefficient from a variety of fixed and reconfigurable reflectarray elements. The model is validated against full-wave simulations for several reflectarray element types, including fixed patches, varactor-loaded patches, and patches on tunable substrates, and is shown to be accurate. As such, it could become a highly useful design tool for quickly deriving the S-curve of reflectarray elements during the initial design stages of reflectarrays.

Broadband Resonant Elements for 5G Reflectarray Antenna Design

The performance investigation of two novel resonant elements is presented in this work for 5G reflectarray antenna design. Two dual resonance elements with wide reflection phase range have been developed from a square patch element by a novel corner bending tactic. The reflection loss and reflection phase range performance of the proposed elements have been compared with conventional square patch element at 26 GHz. The results have shown a reflection phase swing of 629° and 632° for Bent Width and Bent Length elements respectively. The broadband features of proposed elements can radically improve the bandwidth performance of a reflectarray antenna.

Design and Analysis of Different Shapes for Unit-Cell Reflectarray Antenna

This paper presents an analysis and design of unit cell reflectarray antenna using different shapes of radiating elements: square patch, rectangular slot, triangular slot, square loop and Minkowski element are employed in separate unit-cell design operating in X -Band (8-12GHz) at the center frequency of 10GHz. In order to investigate the scattering characteristics of the unit cell studied, commercially available computer models of CST Microwave Studio is used, based on the method of finite integration technique, and using the approach of Floquet (Infinite periodic approach). The analyses of reflection coefficient and reflection phase curves for each resonant element are presented, and Figure of Merit has been defined for the comparison of reflection phase curves obtained by simulation. It has been demonstrated that among the resonant elements square loop acquires higher static phase range of 203°, and the maximum reflection loss of 7.11dB.

A Review of Wideband Reflectarray Antennas for 5G Communication Systems

The advancement in the current communication technology makes it incumbent to analyze the conventional features of reflectarray antenna for future adaptability. This paper thoroughly reviews the design and experimental features of reflectarray antenna for its bandwidth improvement in microwave and millimeter wave frequency ranges. The paper surveys the fundamental and advanced topologies of reflectarray design implementations, which are needed particularly for its broadband features. The realization of its design approaches has been studied at unit cell and full reflectarray levels for its bandwidth enhancement. Various design configurations have also been critically analyzed for the compatibility with the high-frequency 5G systems.

Performances Evaluation of Reflectarray Antenna using Different Unit Cell Structures at 12GHz

Objectives: To compare the performance of different unit cell shapes in the reflectarray antenna design and to provide a reference guide for researchers which reduce the time spent in the study of unit cell performance. Methods/Statistical Analysis: This paper employs related literature review and design. The design aspect being with the study of different unit cell elements, the optimized unit cell sizes are then used to build a reflectarray antenna. The antenna analysis was carried out via simulations on CST studio 2015. Findings: It is observed from exiting literature that although several unit cell have been studied in the design of reflectarry, no comparison has been made from the different unit cells performance. The simulated results show that reflectarray antenna can achieve high gain and high performance with the benefit of low cost, low weight, low transmission losses due to the low profile of the feeding mechanism and their small size. In addition, the study shows that circular patch unit cell elements perform better than the rectangular, triangular and cross shape studied in this paper. Applications/Improvements: This paper shows the performance of four different unit cell shapes at 12HGz, the optimized unit cell are then used to achieve high gain reflector ray antenna.

Angle of Incidence Effects in Reflectarray Antenna Design: Making gain increases possible by including incidence angle effects

The subject of whether or not it is necessary to include a feed field incidence angle in the design of main reflectarrays and subreflectarrays is discussed quantitatively in this article. The performance of reflectarray designs done with and without such incidence angle effects included are compared. The additional gain is achieved if the incidence angle is indeed included in the design process. The immunity of subwavelength elements to incidence angle effects is confirmed and illustrated using individual element patterns. Subreflectarrays designed with such subwavelength elements are shown to exhibit superior performance compared to those using half-wavelength ones.

Design of Single-Feed Multi-Beam Reflectarray Using Iterative Fourier Techniques

Reflectarray antenna with multiple simultaneous beams is a promising antenna candidate for the multiple beam applications. A comprehensive and systematic study on the design of single-feed multi-beam reflectarray antenna is presented in this paper. The traditional direct design method, called aperture field superposition method, is investigated first. It is demonstrated that although this method can generate a multi-beam pattern, it cannot provide satisfactory performances, mainly because of high side lobe level, gain loss and beam deviation. The iterative Fourier technique is then applied to optimize the performances of the multi-beam reflectarray antenna. The required mask and cost function for multi-beam design and the flow of the iterative Fourier techniques are represented. Finally, a Ku-band four beam reflectarray with a single feed is designed using the iterative Fourier techniques and the radiation performances are analyzed and compared with that of single beam, as reference case, and multiple beam designed by aperture field superposition. The numerical results show that a good four beam performance can be obtained by using the iterative Fourier techniques, which suggests that the iterative Fourier technique is suitable for the design of the multi-beam reflectarray antenna with a single-feed.

A Transportable Reflectarray Antenna for Satellite Ku-band Emergency Communications

The design of a Ku-band reconfigurable reflectarray antenna for emergency satellite communications is presented. Bidirectional high data rate satellite links are needed in emergency conditions where other telecommunication infrastructures are not available. In order to operate in this type of scenario, an antenna should be deployable, transportable, and easily repointable. The need of an automatic and fast satellite location and pointing system leads to a completely electronic reconfigurable antenna. The operative bandwidth is from 10.7 to 12.5 GHz for reception and from 14 up to 14.5 GHz for transmission (30% of relative bandwidth). The selected antenna architecture is based on a dual reflectarray system comprising a passive subreflectarray and an active main reflectarray made of reconfigurable 1-bit elementary cells based on PIN diodes.

Design of reflectarray antennas to achieve an optimum near‐field radiation for RFID applications via the implementation of SDM procedure

AbstractThis paper presents the design of reflectarray antennas to radiate an optimum near‐field distribution by using the procedure of steepest decent method to synthesize the impressed phases of reflectarray elements. In particular, the closed‐form formulations used in the electromagnetic modeling were developed for an efficient design. The design was further implemented to realize a reflectarray of microstrip patch elements, which is illuminated by the radiation of a feed antenna at the 2.4 GHz band in the radio frequency identification applications. Numerical investigations as well as experimental measurements over a prototype are presented to validate the feasibility of the developed models and the implemented antenna structure.

Design and Implementation of a Single Layer Circularly Polarized Reflectarray Antenna with Linearly Polarized Feed

A novel microstrip unit cell element with a simple structure is presented for designing circularly polarized reflectarray that converts a linearly polarized incident field into a radiated circularly polarized field. The unit cell element consists of a circular patch with two orthogonal slots etched in it. A parametric study was carried out using CST Microwave Studio (Computer Simulation Technology, worldwide) on the unit cell element to evaluate the effect of the unit cell’s salient parameters. This unit cell element was used to design and implement a prime focus array, which had 3-dB gain bandwidth and 3-dB axial-ratio bandwidth equal to 7.6 and 8.6%, respectively.