Showing papers on "Reflective array antenna published in 2018"

Study on Wide-Angle Scanning Linear Phased Array Antenna

Abstract: Two wide-angle scanning linear array antennas (E- and H-planes scanning linear array antenna) are studied and presented. In order to improve the wide-angle scanning performance of the phased array antenna, a wide beamwidth U-shaped microstrip antenna with the electric walls is designed. The wide-angle scanning linear array antennas are studied in the frequency band from 3.2 to 3.8 GHz. The 3 dB beamwidth of the antenna is 140° in the E-plane scanning linear array center and 220° in the H-plane scanning linear array center at 3.5 GHz. The main beams of the H-plane scanning linear array antenna can scan from −90° to +90° with a gain fluctuation less than 3 dB and a maximum sidelobe level (SLL) less than −5 dB. Simultaneously, the main beam of the E-plane scanning linear array antenna can scan from −75° to +75° with a gain fluctuation less than 3 dB and SLL less than −5 dB. The H- and E-planes scanning linear array antennas with nine elements are fabricated and tested. The measured results have a good agreement with the simulation results.

Finite Large Antenna Arrays for Massive MIMO: Characterization and System Impact

Abstract: Massive MIMO is considered a key technology for 5G. Various studies analyze the impact of the number of antennas, relying on channel properties only and assuming uniform antenna gains in very large arrays. In this paper, we investigate the impact of mutual coupling and edge effects on the gain pattern variation in the array. Our analysis focuses on the comparison of patch antennas versus dipoles, representative for the antennas typically used in massive MIMO experiments today. Through simulations and measurements, we show that the finite patch array has a lower gain pattern variation compared with a dipole array. The impact of a large gain pattern variation on the massive MIMO system is that not all antennas contribute equally for all users, and the effective number of antennas seen for a single user is reduced. We show that the effect of this at system level is a decreased rate for all users for the zero-forcing MIMO detector, up to 20% for the patch array and 35% for the dipole array. The maximum ratio combining on the other hand, introduces user unfairness.

A Survey on Planar Antenna Designs for Cognitive Radio Applications

Abstract: In recent years, the demand for spectrum continues to increase with the advent of various wireless communication applications. However, it is a limited resource and cannot be made available beyond a certain extent. Many of the times, licensed spectrum is free due to its inefficient utilization. So, it can be utilized for other applications to mitigate the problem of limited spectrum availability to some extent. Among the many ways of performing this task, one approach is to use the frequencies in statically licensed spectrum through continuous sensing, which is popularly known as cognitive radio technology. In this model, UWB antennas are employed to monitor the radio environment and narrow band (NB) antennas are adopted for communication. This paper discusses various kinds of planar monopole antennas for cognitive radio applications. They are divided into three categories on the basis of different antennas used in cognitive radio environment. In the first category two separate antennas, which include one UWB antenna and one frequency reconfigurable NB antenna are employed for spectrum sensing and communication, respectively. In the second category, a single port frequency reconfigurable UWB/NB antenna is used. However, it requires an appropriate switching mechanism to switch between the UWB and NB modes. The third category includes dual-port integrated antennas systems, in which one UWB antenna and one frequency reconfigurable NB antenna are integrated on a single substrate. Finally, this paper discuss an opinion of designing multi-port integrated UWB and NB antennas systems to overcome the drawbacks of reconfigurable antennas and to further enhance the spectrum utilization efficiency.

Single-layer double-frequency circularly-polarized reflective array antenna employing graphene units

Abstract: The invention belongs to the technical field of antennae, and discloses a single-layer double-frequency circularly-polarized reflective array antenna employing graphene units. The single-layer double-frequency circularly-polarized reflective array antenna comprises a circularly-polarized feed source and a reflective array, the circularly-polarized feed source is formed by a circularly-polarized horn antenna, the upper surface of the reflective array is formed by alternatively arranging high-frequency graphene units and low-frequency graphene units, and the lower surface of the reflective arrayis provided with a frequency selection surface. The reflective array is of a single-layer structure, graphene is introduced as a radiating body of the reflective array units, and compared with a conventional metal reflective array antenna, the single-layer double-frequency circularly-polarized reflective array antenna is advantaged in that the performance of the reflective array antenna in the terahertz frequency range is effectively improved; a rotary unit method is employed to carry out phase compensation, the lower surface of the reflective array is provided with the frequency selection surface, and mutual coupling between units of the reflective array in two different frequency ranges is effectively reduced.

Dual frequency band dual polarization spaceborne cloud-rain measurement radar system

Abstract: The invention discloses a dual frequency band dual polarization spaceborne cloud-rain measurement radar system which is mainly composed of an antenna subsystem, a radio frequency subsystem, a digitalsubsystem, a monitoring subsystem and a power supply subsystem. The antenna subsystem adopts a parabolic reflector/microstrip reflective array antenna feeder system, and comprises a parabolic reflector/microstrip reflective array antenna, a Ka frequency band active phased array feed source, a W frequency band beam waveguide feed system and a Ka/W frequency band shared parabolic reflector/microstrip reflective array antenna. The radio frequency subsystem is connected with the Ka frequency band active phased array feed source, the W frequency band beam waveguide feed system and the digital subsystem. The digital subsystem is connected with a terminal. The system provided by the invention has the advantages that the three-dimensional vertical structure information of clouds and precipitationin the field of view can be quantitatively acquired; and the acquired global cloud-rain three-dimensional structure data can be applied to three-dimensional high-precision inversion of atmospheric clouds and precipitation, can be applied to global extreme weather monitoring and forecasting, and can be applied to atmospheric science and numerical simulation studies.

Ninja array antenna: novel approach for low backscattering phased array antenna

Abstract: This study presents a novel concept of a low backscattering phased array antenna, a Ninja array antenna. One of the advantages of the Ninja array antenna over the conventional phased array antenna is low backscattering performance over its operating frequency band, which is not available using a conventional phased array antenna with a band-pass radome. The Ninja array antenna is designed in the same manner as the design of reflectarrays, so that the main lobe of its scattering field is directed to a specific direction except for backscattering one. As a result, its backscattering is reduced in comparison with that of the conventional phased array antenna. Although the Ninja array antenna is composed of non-identical array elements such as the reflectarray, it works as a phased array antenna because desired amplitude and phase of excitation can be obtained numerically via an array element pattern. Numerical simulation is performed and the scattering/radiation performance of the Ninja array antenna is demonstrated.

Large-aperture planar achromatic reflective array antenna

Abstract: The invention provides a large-aperture planar achromatic reflective array antenna including a horn feed source, a multilayer metamaterial under the feed source, and a reflective layer attached to theunderlying metamaterial; wherein each layer of metamaterial includes a dielectric plate and a non-periodically arranged metal resonant element printed on the front side of the dielectric plate. By using an advantages that the electromagnetic response of the metamaterial to an incident electromagnetic wave can be artificially modulated, the required phase distribution satisfying the achromatic focusing in a certain frequency band can be obtained through an optimization algorithm, and then the response of the incident broadband electromagnetic wave is changed by using the metal resonant units with different structures according to the phase distribution so as to achieve broadband continuous achromatic focusing. The large-aperture planar achromatic reflective array antenna uses the new metamaterial structure and a phase distribution mode, has the advantages of simple structure, large aperture, large working bandwidth and low cost, and has the same response to all polarizations and is applicable to various polarization electromagnetic waves.

Micro-strip reflective array antenna

Abstract: The invention discloses a micro-strip reflective array antenna, and mainly solves problems in the prior art that the structure is complicated and the bandwidth is narrower. The micro-strip reflectivearray antenna is formed by periodically arranging a plurality of horizontally and longitudinally uniformly arranged paster units. A reflecting phase of each paster unit is different, and an arrangement period D is 0.3-0.5 Lambda. Each unit successively comprises a paster (1), a medium substrate (2) and a floor (3) from top to bottom. The paster (1) uses a circular structure. The circular paster isprovided with two pairs of gaps (11). The two pairs of the gaps (11) are positioned at two ends of two mutual perpendicular diameter lines of the circle. The micro-strip reflective array antenna is capable of improving the gain bandwidth, simple in structure, smaller in cross-polarization, and good in unit frequency characteristic curve parallelism, and can be used for the electromagnetic wave regulation and control of a microwave band.

X-Band Patch Array Antenna

Abstract: The following contains a detailed study as well as design of the hybrid patch array antennas and their application in transmission of signals unaltered. The different dimensions of design including substrate material, width, distance between two patch and other elements have been done through various theoretical analysis and techniques. Practical approach for triangular patches according to the distribution of current is summarized below. The mathematical calculation related to the array is emphasized and critical factors are also considered while determining the development of this antenna.

A sector beam scanning reflective array antenna

Abstract: The invention discloses a novel fan-shaped beam scanning and reflecting array antenna, which is composed of two metal plates, a feed antenna, a waveguide reflecting array, a support part, a transitionpart and a mechanical adjusting part. Wherein the two metal plates are arranged opposite each other in parallel and form a hollow square box body with the support part, and the feed antenna is arranged in the middle of the rear direction between the two metal plates and the opening faces the front; The waveguide reflector array is arranged on the forward end face between two metal plates and is opposite to the feed antenna. The transition part extends from the edge of the metal plate where the feed antenna is located to the rear free space respectively. A mechanical adjust part is connected with that waveguide reflection array one by one and adjust the waveguide length respectively. The application of the antenna of the invention can obtain a fan-shaped beam and ultimately realize the horizontal scanning function, and the device has the advantages of small volume, reduced sidelobe, low manufacturing cost, concentrated energy and superior performance.

Focusing transmission reflective array antenna design method for unequal power distribution

Abstract: The invention discloses a focusing transmission reflective array antenna design method for unequal power distribution. The focusing transmission reflective array antenna design method comprises the achieving steps that 1, reflector array antenna units are generated; 2, the scales of reflector array antennae are determined; 3, a compensation phase table is drawn; 4, energy receiving focus information is determined; 5, the compensation phases of the reflector array antenna units are calculated; 6, the lengths of cross metal patches of the reflector array antenna units are adjusted; 7, he reflector array antennae are constructed; 8, weighting value matrixes are generated. By adopting the focusing transmission reflective array antenna design method for unequal power distribution, near field focusing characteristics of multi-feed-source multi-focus unequal power distribution of reflective magnetic metasurfaces are achieved, and the multiple-input-multiple-output (MIMO) demands of wireless communication and wireless sensor networks are met.

Microstrip reflective array antenna based on sub-wavelength spiral phase shift unit

Abstract: The invention relates to a microstrip reflective array antenna based on sub-wavelength spiral phase shift units. The antenna comprises phase shift units composed of spiral phase shift arms. The single-layer sub-wavelength six-arm spiral phase shift unit is used, the range of reflection phase of the unit exceeds 500 degrees, the problem that the reflection phase range of a traditional sub-wavelength reflective array unit is hard to reach 360 degrees is solved, a reflection phase curve is smooth, the linearity is high, and help is provided for design of a broadband reflective array; and the microstrip reflective array antenna based on single-layer sub-wavelength spiral phase shift units is high in radiation performance, simple in antenna structure, low in cost and easy to realize in engineering.

Reflective array antenna based on substrate integrated waveguide slot antenna

Abstract: The invention provides a reflective array antenna based on a substrate integrated waveguide slot antenna. The reflective array antenna is based on the substrate integrated waveguide slot antenna unit,a first slot is etched on the upper surface of an upper substrate integrated waveguide, the slot antenna with a radiation characteristic is generated, and a second slot is etched on the metal interface of two substrate integrated waveguides, so that the transmission of energy between the upper and lower substrate integrated waveguides is realized. The function of linear phase adjustment is realized by adjusting the length of the lower substrate integrated waveguide. The reflective array antenna unit realizes the design of a unit structure by adopting the substrate integrated waveguides, and is simple in structure, easy to machine and relatively low in cost and weight, so that the reflective array antenna can be produced in large scale.

Two-dimensional scanning single-layer folded reflective array antenna

Abstract: A two-dimensional scanning single-layer folded reflective array antenna disclosed by the present invention comprises a feed source antenna, a main reflecting board, a polarization grid and a pluralityof length controllable devices. The feed source antenna and the main reflecting plate are integrated on a same single-layer printed circuit board, one ends of the length controllable devices are connected with the main reflecting plate, and the other ends are connected with the polarization grid. By adjusting the lengths of the length controllable devices, the inclination angle of the polarization grid is adjusted, and the height of the geometric center of the polarization grid is constant. According to the present invention, by the single-layer printed circuit board, the assembly errors of the feed source antenna can be reduced, and the cost is reduced. According to the present invention, by adjusting the inclination angle of the polarization grid via the length controllable devices, thetwo-dimensional scanning can be realized. Moreover, according to the present invention, the scanning precision is improved effectively. In addition, the main reflecting plate of the present inventionis fixed, so that the integration with an active circuit is easier.

Foldable reflective array multi-beam antenna with wide scanning angle

Abstract: The present invention discloses a foldable reflective array multi-beam antenna with a wide scanning angle. The antenna comprises three sub foldable reflective array multi-beam antennas consisting of aleft-reflection foldable reflective array antenna located at a left side, a front-reflection foldable reflective array antenna located at the middle portion and a right-reflection foldable reflectivearray antenna located at the right side. The foldable reflective array multi-beam antenna achieves functions such as space diversity, frequency reuse and the like, is large in high-gain wave beam coverage angle range, overcomes defects of a traditional antenna with a low large-coverage angle antenna gain and a small high-gain antenna coverage angle, has characteristics of a low plane surface, a high gain, a high integration level, easy manufacturing and low cost, can perform space scanning in a condition of reducing the number of radio frequency channels and can flexibly close corresponding radio frequency channels when a corresponding space angle does not need to work to achieve a purpose of energy saving; and moreover, a substrate benefiting an integration microwave circuit and variousmicrowave switching devices is employed to integrate waveguide feed to facilitate using of the foldable reflective array multi-beam antenna on various communication devices.

Dielectric matching layer-based solid-state plasma scanning antenna and phase compensation method

Abstract: The invention discloses a dielectric matching layer-based solid-state plasma scanning antenna and a phase compensation method, and proposes a dielectric matching layer technology-based phase compensation method. A phase curve moves upwards or downwards to achieve 0-360 degree phase compensation by a mode that a matching layer is additionally arranged above a reflective array antenna unit to changeoptical path difference, if the phase curve does not confirm to 0-360 degrees, a medium with different thicknesses or different reflectivity can be used as the matching layer for phase compensation,and finally, the compensated array unit forms a reflective surface of the antenna by an arraying mode. A relation between a parameter and a phase compensation angle of the reflective array is built byan interpolation mode, solid-state plasma is employed to substitute metal to work and is implemented by an array comprising S-PIN units, the S-PIN units are isolated by an isolation layer, the S-PINunit array is controlled to be simulated by programmable logic arrays loaded at two ends, so that space scanning can be achieved by the planar reflective array antenna.