Active antenna

About: Active antenna is a research topic. Over the lifetime, 2246 publications have been published within this topic receiving 26493 citations.

Performance Analysis of RIS-SSK in the Presence of Hardware Impairments

Abstract: Reconfigurable Intelligent Surface-based Space Shift Keying (RIS-SSK) was recently proposed as a promising transmission technique. In order to design strategic radio environments, this system takes advantage of RIS-based communication and adjusts the propagation channels. Furthermore, using SSK as a special case of the Spatial Modulation (SM) reduces the detection complexity by using only the index of the active antenna to transmit the data. However, when considering an effective RIS-SSK system, the transmit antenna is modeled by spatial constellation points with different weights. This requires the knowledge of Channel State Information (CSI), including the index of the activated antenna at each transmission which is impractical. In contrast, blind RIS-SSK does not require this information, decreasing its complexity and increasing its practicality. In this paper, a blind RIS-SSK system without phase-adjusting is studied in the presence of hardware impairments and compared to the standard SSK. Additionally, analytically error probability expressions based on the Maximum Likelihood (ML) detector are developed and proven with simulations. The results illustrate the negative effects of modeling the hardware impairments for robust RIS-SSK system implementation.

Active integrated antenna techniques for beam control

Abstract: Active integrated antenna techniques have high potential for giving smaller size, lighter weight, lower cost and higher efficiency, in particular to millimeter-wave circuit-antenna systems. This paper gives a review of active integrated antenna techniques with emphasis on beam steering and retrodirective antenna arrays. Various beam steering operations of integrated antenna oscillator arrays using locking phenomena are presented. Beam steering arrays of such type have the feature that phase shifters are not necessary in the arrays. Arrays with higher harmonic output radiation can enlarge the beam steering range. Arrays of locked active antennas which operate as self-oscillating mixers can be beam controllable receiving antennas.

Active antenna array and method for calibration of the active antenna array

Abstract: The disclosure relates to an active antenna array (10) for a mobile communication system which comprises a plurality of receive paths (30-1,..., 30-N), a control unit (105) for generating a sounding signal (110), and a coupler for coupling the sounding signal (110) into at least one of a plurality of receive paths (30-1,..., 30-N), A switch (190) is used to switch the output of one the plurality of receive paths (30-1,..., 30-N) between one of a receiver (Rx) and a calibration unit. The disclosure also provides a method for the calibration of the active antenna array (10) which comprises generating (210) an initial sounding signal (110), coupling the Initial sounding signal (110) into at least one of a plurality of receive paths (30-1,..., 30-N) to generate an adjusted sounding signal (110'), comparing (220) the adjusted sounding signal (110') with an initial sounding signal (110) and than generating (225) calibration parameters.

Field trial results for vertical sectorization in LTE network using Active Antenna System

Abstract: Previous work has reported that vertical sectorization can efficiently improve the capacity of LTE network using Active Antenna System (AAS) based on simulation results, however, its performance in real-world scenario still needs to be evaluated and verified for future deployment. Thus, this study conducts an evaluation of vertical sectorization in LTE field trial with single user. The field trial results show that the average downlink throughput of the single user is reduced compared to the one of traditional network, which results in the deterioration of user experience. Furthermore, we examine field data and antenna parameters, and verify that the co-frequency interference between the inner and outer cells is the main reason for average downlink throughput decrease in field trial. Obviously, without proper interference suppression or can-celation mechanisms, the vertical sectorization can not improve the user experience. Therefore, some practical suggestions on the deployment of vertical sectorization in LTE network are proposed.

Point-actuated aperture antenna development

Abstract: Consistent changes in both commercial and military satellite needs have created the need for antennas with additional flexibility. Military surveillance may require the ability to focus the radiation pattern to increase the bandwidth or resolution in a certain area. Commercial satellites may need to change coverage area to meet evolving consumer needs or to compensate for adverse weather or atmospheric conditions. Recent studies on active antennas have shown that the far field radiation pattern can be changed by altering the shape of the sub reflector. In this research, we control the antenna far field radiation pattern by controlling the shape of the sub reflector using numerous point actuators placed perpendicular to the reflector surface. The PZT stack coupled with a stick-slip mechanism give the point actuators used in this design an advantage over similar studies using PZT bimorph or PVDF actuators to generate the actuation force in that the displacement can be maintained without the continuous application of voltage. An electromechanical model is used to describe the motion of the stack, and the stick slip mechanism is modeled similar to power screw-type actuators. A combined finite element/electromagnetic analysis code is used to determine the desired shape of the reflector, and the corresponding actuator displacements. The final shape of the reflector is verified using stereo photogrammetry.