Wideband Planarized Dual-Linearly-Polarized Dipole Antenna and Its Integration for Dual-Circularly-Polarized Radiation

© 2002-2011 IEEE. A planarized dual-linearly-polarized (dual-LP) antenna and an integrated dual-circularly-polarized (dual-CP) antenna are proposed in this letter. For the dual-LP antenna, two groups of dipoles are fed by two balun-included feed networks to achieve ±45° polarizations. The feed networks and the radiators are printed on two sides of a substrate, forming a fully planar structure. Taking advantage of its planar configuration, the dual-LP antenna is further integrated with a wideband coupler to realize dual-CP radiation. The coupler is bent and squeezed into the space between the radiators and the reflector, leading to a compact structure. Both the dual-LP antenna and the dual-CP antenna have very stable radiation performances across a wide operating band >66%

The Murchison Widefield Array: Design Overview

The Murchison Widefield Array (MWA) is a dipole-based aperture array synthesis telescope designed to operate in the 80-300 MHz frequency range. It is capable of a wide range of science investigations, but is initially focused on three key science projects. These are detection and characterization of 3-dimensional brightness temperature fluctuations in the 21cm line of neutral hydrogen during the Epoch of Reionization (EoR) at redshifts from 6 to 10, solar imaging and remote sensing of the inner heliosphere via propagation effects on signals from distant background sources,and high-sensitivity exploration of the variable radio sky. The array design features 8192 dual-polarization broad-band active dipoles, arranged into 512 tiles comprising 16 dipoles each. The tiles are quasi-randomly distributed over an aperture 1.5km in diameter, with a small number of outliers extending to 3km. All tile-tile baselines are correlated in custom FPGA-based hardware, yielding a Nyquist-sampled instantaneous monochromatic uv coverage and unprecedented point spread function (PSF) quality. The correlated data are calibrated in real time using novel position-dependent self-calibration algorithms. The array is located in the Murchison region of outback Western Australia. This region is characterized by extremely low population density and a superbly radio-quiet environment,allowing full exploitation of the instrumental capabilities.Comment: 9 pages, 5 figures, 1 table. Accepted for publication in Proceedings of the IEE

Design of a Low-Profile Dual Linearly Polarized Antenna Array for mm-Wave 5G

This work proposes a dual linearly polarized antenna array for 5G mm-wave band, which is designed to be compatible with planar printed circuit board technology. The proposed antenna is engineered with a focus on simplifying the antenna geometry and eliminating any critical issues that may arise in antenna manufacturing. The proposed antenna has been evaluated, finding a 7% impedance bandwidth centered around 27.28 GHz. Additionally, the beam steering capability of the antenna is found to cover a ±30% angular width for both linear polarizations. These findings highlight the potential of the proposed antenna for use in 5G mm-wave band applications, where compatibility with planar printed circuit board technology and simplified antenna geometry are essential design requirements

Adaptive multibeam antennas for spacelab. Phase A: Feasibility study

The feasibility was studied of using adaptive multibeam multi-frequency antennas on the spacelab, and to define the experiment configuration and program plan needed for a demonstration to prove the concept. Three applications missions were selected, and requirements were defined for an L band communications experiment, an L band radiometer experiment, and a Ku band communications experiment. Reflector, passive lens, and phased array antenna systems were considered, and the Adaptive Multibeam Phased Array (AMPA) was chosen. Array configuration and beamforming network tradeoffs resulted in a single 3m x 3m L band array with 576 elements for high radiometer beam efficiency. Separate 0.4m x 0.4 m arrays are used to transmit and receive at Ku band with either 576 elements or thinned apertures. Each array has two independently steerable 5 deg beams, which are adaptively controlled

HI Epoch of Reionization Arrays

There are few data available with which to constrain the thermal history of the intergalactic medium (IGM) following global recombination. Thus far, most constraints flow from analyses of the Cosmic Microwave Background and optical spectroscopy along a few lines of sight. However, direct study of the IGM in emission or absorption against the CMB via the 1S hyperfine transition of Hydrogen would enable broad characterization thermal history and source populations. New generations of radio arrays are in development to measure this line signature. Bright foreground emission and the complexity of instrument calibration models are significant hurdles. How to optimize these is uncertain, resulting in a diversity in approaches. We discuss recent limits on line brightness, array efforts including the new Large Aperture Experiment to Detect the Dark Ages (LEDA), and the next generation Hydrogen Reionization Array (HERA) concept.Comment: 8 pages, 4 figures, 1 table. Invited review to the 11th Asian-Pacific Regional IAU Meeting 2011, NARIT Conference Series, Vol. 1 eds. S. Komonjinda, Y. Kovalev, and D. Ruffolo (2012

Matching the Directions of Electric Fields from Triboelectric and Ferroelectric Charges in Nanogenerator Devices for Boosted Performance

This research was supported by Riga Technical University's Doctoral Grant program. This research was also supported by the European Regional Development Fund within the project ‘‘Hybrid energy harvesting systems’’ 1.1.1.1./16/A/013.Embedding additional ferroelectric dipoles in contacting polymer layers is known to enhance the performance of triboelectricnanogenerator (TENG) devices. However, the influence of dipoles formed between the triboelectric surface charges on two contacting ferroelectric films has been ignored in all relevant studies. We demonstrate that proper attention to the alignment of the distinct dipoles present between two contacting surfaces and in composite polymer/BaTiO3 ferroelectric films can lead to up to four times higher energy and power density output compared with cases when dipole arrangement is mismatched. For example, TENG device based on PVAc/BaTiO3 shows energy density increase from 32.4 μJ m−2 to 132.9 μJ m−2 when comparing devices with matched and mismatched dipoles. The presented strategy and understanding of resulting stronger electrostatic induction in the contacting layers enable the development of TENG devices with greatly enhanced properties.Riga Technical University's Doctoral Grant program; European Regional Development Fund 1.1.1.1./16/A/013; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART

Connected array antennas : analysis and design

Many of today's satellite communication and radar systems necessitate phased array antennas that are capable of wideband/multi-band operation and good polarization purity over a wide scan volume. However, the antenna solutions typically used for wideband wide-scan applications trade-off matching performance against polarization purity. For this reason, in recent years, a new approach has arisen for the design of broadband arrays, aiming at reducing cross polarization. This antenna solution consists of arrays of long dipoles or slots periodically fed, and are referred to as connected arrays of slot or dipoles. Connected array antennas represent one of the most promising concepts in the field of very wideband arrays, for being able to achieve both broad band and low cross polarization. The wideband performance is due to the fact that the connections between neighboring elements allow currents to remain nearly constant with frequency. Another attractive feature of connected arrays is their capability to achieve good polarization purity, in virtue of the planarity of the radiators. Besides the advantageous physical properties, connected arrays are based on simple geometries that lead to the derivation of analytical solutions for the antenna parameters. Closed-form expressions based on a spectral Green's function representation are derived for the input impedance, the current distribution over the array and the radiation patterns. Important advantages result from this representation with respect to numerical solutions: above all, the reduction of computational costs and the gain in physical insight on the wave phenomena. A convenient circuit representation of the array unit cell is derived. The circuit describes rigorously and analytically the transition between free-space radiation and guiding transmission line. Contrarily to standard Thévenin circuit for receiving antennas, this representation can be used to evaluate the power scattered by the antenna. The results have been applied to the analysis of the scattering and absorption of a real connected-dipole prototype array backed by a frequency selective ground plane. Good agreement was achieved between measurements and results from the equivalent network. A novel measurement technique based on passive RCS measurements in the main planes was used to characterize the active matching of the radiating part of the antenna in transmission. Finiteness effects can be particularly severe in connected arrays, due to electrical connection and the high mutual coupling between the elements. As a consequence, the overall behavior of a finite wideband array can be sensibly different with respect to infinite array analysis. Thus, it is crucial to include edge effects already in the preliminary assessment of the array performance. An efficient numerical procedure is derived for the characterization of the edge effects. The method requires only one unknown per elementary cell, independently from the cell geometrical parameters. This is possible thanks to the use of an appropriate connected array Green's function in the integral equation. This procedure is of general applicability and can be used for arrays with and without backing reflectors and for arbitrary scan angle. An alternative analytical representation is also derived to provide physical insight on the nature of the edge-waves. The analytical approximation of the spatial current distribution on the finite array is derived, for the specific case of a connected array of dipoles operating in free space, and scanning only in the E-plane. The key step is to represent the total current as sum of the infinite array contribution plus edge-born waves. The final analytical expression is given in terms of Fresnel functions and allows qualitative considerations on the nature of the electric current distribution, in terms of spreading and attenuation. The analytical expressions represent a powerful tool that can be used both for modeling and design. A connected array of dipoles with 40% bandwidth, when scanning in elevation to 45o, has been designed. Practical designs require the implementation of ad hoc feed structures that avoid common-mode currents to propagate on the feed lines. This problem has been addressed and feed structures that perform common-mode rejection have been designed. Measurements form a prototype demonstrator were presented for validation and showed good performance

Ultra-Wideband Phased Arrays for Small Mobile Platforms

This dissertation presents the development of a new class of Ultra-Wideband (UWB) apertures for aerial applications by introducing designs with over 50:1 bandwidth and novel differential feeding approaches. Designs that enable vertical integration for flip-chip millimeter-wave (UWB) transceivers are presented for small aerial platforms. Specifically, a new scalable tightly coupled array is introduced with differential feeding for chip integration. This new class of beam-forming arrays are fabricated and experimentally tested for validation with operation from as low as 130 MHz up to 18 GHz. A major achievement is the study of millimeter wave beamforming designs that operate from 22-80 GHz, fabricated using low-cost printed circuit board (PCB) methods. This low-cost fabrication approach and associated testing of the beamforming arrays are unique and game-changing

Low Cost Scanning Arrays

Over the past decades, phased arrays have played a significant role in the development of modern radar and communication systems. The availability of printed circuit technology and ease of integration with microwave components, as well as the development of low profile and low weight approaches, have also played an important role in their conformal adaptation. However, fabrication costs remain prohibitive for many emergent platforms, including 5G base stations and autonomous vehicles, when compared to a conventional mechanically steered passive array. Therefore, cost reductions in the fabrication and integration of modern phased arrays are essential to their adaptation for many upcoming commercial applications. Indeed, although phased array design methods are well-understood, even for wideband and wide-angle scanning applications, their fabrication is still based on high-cost, low-yield printed circuit technology. With this in mind, this dissertation focuses on a new planar aperture topology and low-cost techniques for phased array methodologies. The first part of the thesis presents new fabrication advancements using commercially available multi-layered printed circuit technologies. We discuss methods for low cost fabrication while still maintaining performance and design constraints for planar array apertures. The second part of the dissertation presents a novel Integrated Planar Array (IPA) at S-Band and discusses dramatic cost reductions for multi-function radar applications. Performance and cost benefits are presented, and fabrication techniques to exploit an emerging class of high-speed digital laminates are discussed. These are compatible with high-volume, high-yield production, while reducing aperture cost by 75% when compared to conventional approaches. Performance of a planar array employing a pin-fed dual-polarized antenna element with active VSWR Overall, this dissertation addresses several manufacturing and performance challenges in realizing affordable planar phased arrays using low cost fabrication without performance compromise. As commercial interest in phased array technology is anticipated to grow, the proposed approaches for phased array design and fabrication will enable quick turnaround times for mainstream adoption