348 research outputs found
A Compact Single Layer Reflectarray Antenna Based on Circular Delay-Lines for X-band Applications
This paper presents a compact single layer reflectarray antenna based on a diagonally notched square patch and a pair of circular delay lines, for X-band applications. The length and width of circular delay-lines are varied and optimized to attain a linear phase range of more than 600º. The effect of incident angle in TE and TM modes at 0º, 15º and 30º is studied, which offers stable angular phase range. The hybrid Finite Element Boundary Integral (FEBI) method is used for simulation of the whole reflectarray system comprising of 27 × 27 elements and being fabricated on a low cost FR-4 laminate. The measured gain of 24.5 dBi with aperture efficiency of 49.5% is achieved at 10 GHz. The proposed design provides the measured 1-dB gain bandwidth of 12.5% and 3-dB gain bandwidth of 34%. The simulated and measured side-lobe-levels and cross polarizations are less than –25 dB and –40 dB respectively
Reconfigurable Reflectarrays and Array Lenses for Dynamic Antenna Beam Control: A Review
Advances in reflectarrays and array lenses with electronic beam-forming
capabilities are enabling a host of new possibilities for these
high-performance, low-cost antenna architectures. This paper reviews enabling
technologies and topologies of reconfigurable reflectarray and array lens
designs, and surveys a range of experimental implementations and achievements
that have been made in this area in recent years. The paper describes the
fundamental design approaches employed in realizing reconfigurable designs, and
explores advanced capabilities of these nascent architectures, such as
multi-band operation, polarization manipulation, frequency agility, and
amplification. Finally, the paper concludes by discussing future challenges and
possibilities for these antennas.Comment: 16 pages, 12 figure
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
work 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
Bandwidth Improvement in Large Reflectarrays by Using True-Time Delay
A significant improvement in the bandwidth of large reflectarrays is demonstrated using elements which allow true-time delay. Two identical, large reflectarrays have been designed using different phase distributions to generate a collimated beam. In the former, the phase distribution is truncated to 360deg as is usual in reflectarray antennas, while in the second, the true phase delay is maintained (three cycles of 360deg). The chosen phase-shifter elements are based on previously measured and validated patches aperture-coupled to delay lines. The radiation patterns for both reflectarrays have been computed at several frequencies and the gain is represented as a function of frequency for both cases. Bandwidth curves are presented as a function of the reflectarray size
Analysis, Design and Applications of Reflectarrays
A brief overview of reflectarray antennas mainly focused on some efficient analysis and design techniques and on recent developments has been presented. A technique based on the local periodicity and Method of Moments in Spectral Domain has been presented as very efficient for the analysis of reflectarray antennas. The technique has been validated by comparing simulations and measurements in several breadboards. Based on the previous analysis technique, several design procedures have been implemented for different antenna performances, including requirements of broad-band, dualfrequency and stringent contoured beams. Finally some recent developments for applications in space and LMDS antennas are presented
MEMS-reconfigurable metamaterials and antenna applications
This paper reviews some of our contributions to reconfigurable metamaterials,
where dynamic control is enabled by micro-electro-mechanical systems (MEMS)
technology. First, we show reconfigurable composite right/left handed
transmission lines (CRLH-TLs) having state of the art phase velocity variation
and loss, thereby enabling efficient reconfigurable phase shifters and
leaky-wave antennas (LWA). Second, we present very low loss metasurface designs
with reconfigurable reflection properties, applicable in reflectarrays and
partially reflective surface (PRS) antennas. All the presented devices have
been fabricated and experimentally validated. They operate in X- and Ku-bands.Comment: 8 pages; 8 figures; International Journal of Antennas and Propagatio
Demonstration of a Shaped Beam Reflectarray Using Aperture-Coupled Delay Lines for LMDS Central Station Antenna
A shaped-beam reflectarray based on patches, aperture-coupled to delay lines is demonstrated for local multipoint distribution system (LMDS) central station antennas, in the 10.10-10.70 GHz band. The antenna must cover a 60deg-sector in azimuth with a squared cosecant pattern in elevation. The design process consists of two steps. First, a phase-only pattern synthesis technique is applied to obtain the required phase-shift distribution on the reflectarray surface which generates the shaped pattern. The second stage consists of determining the length of the delay lines, aperture-coupled to the square patches, in order to achieve the phase distribution synthesized in the previous step. Two reflectarray antennas have been designed, one for vertical (V) and the other for horizontal (H) polarization. A breadboard for V-polarization has been manufactured and tested in an anechoic chamber, showing a good agreement between theoretical and measured radiation patterns
Reflectarray antennas for dual polarization and broadband telecom satellite applications
A reflectarray antenna with improved performance is proposed to operate in dual-polarization and transmit-receive frequencies in Ku-band for broadcast satellite applications. The reflectarray element contains two orthogonal sets of four coplanar parallel dipoles printed on two surfaces, each set combining lateral and broadside coupling. A 40-cm prototype has been designed, manufactured, and tested. The lengths of the coupled dipoles in the reflectarray cells have been optimized to produce a collimated beam in dual polarization in the transmit and receive bands. The measured radiation patterns confirm the high performance of the antenna in terms of bandwidth (27%), low losses, and low levels of cross polarization. Some preliminary simulations at 11.95 GHz for a 1.2-m antenna with South American coverage are presented to show the potential of the proposed antenna for spaceborne antennas in Ku-band
Analysis of dual-reflector antennas with a reflectarray as subreflector
In this paper, a modular technique is described for the analysis of dual-reflector antennas using a reflectarray as a subreflector. An antenna configuration based on a sub-reflectarray and a parabolic main reflector provides better bandwidth than a single reflectarray, and has a number of advantages compared with a conventional dual-reflector antenna. Examples include the possibility of beam shaping by adjusting the phase on the sub-reflectarray, and potential capabilities to scan or reconfigure the beam. The modular technique implemented for the antenna analysis combines different methods for the analysis of each part of the antenna. First, the real field generated by the horn is considered as the incident field on each reflectarray element. Second, the reflectarray is analyzed with the same technique as for a single reflectarray, i.e., considering local periodicity and the real angle of incidence of the wave coming from the feed for each periodic cell. Third, the main reflector is analyzed using the Physical Optics (PO) technique, where the current on the reflector surface is calculated by summing the radiation from all the reflectarray elements. Finally, the field is calculated on a rectangular periodic mesh at a projected aperture, and then a time-efficient fast Fourier transform (FFT) algorithm is used to compute the radiation pattern of the antenna. The last step significantly improves the computational efficiency. However, it introduces a phase error, which reduces the accuracy of the radiation patterns for radiation angles far away from the antenna's axis. The phase errors have been evaluated for two integration apertures. It has been demonstrated that accurate patterns are obtained in an angular range of plusmn6deg, which is sufficient for large reflectors. The method of analysis has been validated by comparing the results with simulations obtained from GRASP8. Finally, the theoretical beam-scanning performance of the antenna is analyzed
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