Joint Design and Co-integration of Antenna-IC Systems

An overview of design challenges for beamforming active antenna arrays, which are needed to meet high-performance demands of future emerging applications, is presented. The critical role of antenna element mutual coupling on the receiving system sensitivity of array receivers, and effective radiated power of MIMO-type array transmitters is discussed. Trade-offs, common misconceptions, and practical examples are shown and discussed. Techniques towards strong integration between antennas and LNAs/PAs that blurs the geometrical boundaries between them are presented. This will cover mm-wave antenna design examples, where direct matching of active devices to their optimal source/load impedances eliminates the losses of 50-Ohm impedance matching networks. An antenna-integrated high-efficiency (Doherty) PA, operating at the sub-6 GHz band and utilizing active load modulation, will be taken as an on-antenna power combining example, including optimization aspects and over-the-air characterization

Towards a uniform evaluation of the science quality of SKA technology options: Polarimetrie aspects

We discuss how to evaluate SKA technology options with regard to science output quality. In this work we will focus on polarimetry. We review the SKA specification for polarimetry and assess these requirements. In particular we will use as a illustrative case study a comparison of two dish types combined with two different feeds. The dish types we consider are optimized axi-symmetric prime-focus and offset Gregorian reflector systems; and the two feeds are the Eleven-feed (wideband) and a choked horn (octave band). To evaluate the imaging performance we employ end-to-end simulations in which given sky models are, in software, passed through a model of the telescope design according to its corresponding radio interferometrical measurement equation to produce simulated visibilities. The simulated visibilities are then used to generate simulated sky images. These simulated sky images are then compared to the input sky models and various figures-of-merit for the imaging performance are computed. A difficulty is the vast parameter space for observing modes and configurations that exists even when the technology is fixed. However one can fixed certain standard benchmark observation modes that can be applied across the board to the various technology options. The importance of standardized, end-to-end simulations, such as the one presented here, is that they address the high-level science output from SKA as a whole rather than low-level specifications of its individual parts

Characteristic Basis Function Analysis of Large Aperture-Fed Antenna Arrays

The Characteristic Basis Function Method (CBFM) is applied to rapidly compute the impedance and radiation characteristics of electrically large aperture-fed antenna arrays. A stationary formula for the antenna input admittance matrix is expressed in terms of a product of matrix blocks that are readily available from a method of moment formulation. Numerical results are shown for large arrays of waveguide antennas requiring more than 2 million basis functions, which is reduced by a factor of 9000, so that the solution for the currents are still obtainable in-core on a single desktop computer, while being orders faster than commercial software codes or a standard MoM approach, provided that sufficient memory is available for the Gaussian elimination

Synthesis of circular isophoric sparse arrays by using compressive-sensing

A design approach for large-scale sparse arrays based on Compressive Sensing has been recently introduced in the literature and extended to include complex EM effects and scan performance. However, that approach cannot directly control the number of excitation amplitudes. Here, we apply a two-step procedure that first synthesizes continuous rings with unconstrained amplitudes using an iterative ℓ1-norm minimization approach, and then replaces them with a circular isophoric ring array with a number of elements proportional to the original amplitude of each ring. The procedure is demonstrated for an isotropic array of a 10λ radius, for which a reference solution based on the analytical density-taper approach is available in the literature. Results show the capability of the proposed method to achieve a significant reduction of the array aperture (20%) with 25% less elements or 4dB lower peak side lobe level

Towards the understanding of the interaction effects between reflector antennas and phased array feeds

A computationally efficient numerical procedure has been developed and used to analyze the mutual interaction effects between an electrically large reflector antenna and a phased array feed (PAF). The complex electromagnetic behavior for such PAF systems is studied through a few simple and didactical examples, among which a single dipole antenna feed, a singly-excited antenna in an array of 20 dipoles, and a fully-excited array. These examples account for the effects of the ground plane, active loading (low noise amplifiers), and beamforming scenario, and are used to illustrate the differences between single-port feeds and PAFs

Reconfigurable aperiodic array synthesis by Compressive Sensing

Aperiodic arrays represent an attractive technology for applications requiring multiple pencil beams or contour beams, such as in radars, satellite communication and mw-sensor systems. These antennas are typically designed to either produce high-directivity beams over a given scan range or a single beam with a specified complex shape. In this manuscript we present a CS approach for the synthesis of a single aperiodic array layout capable of radiating multiple beams with different shapes The approach aims at designing reconfigurable arrays with least number of elements as well as the optimal excitation set for each of the desired beams. Preliminary results for an array providing both pencil and a flattop coverage are presented

Wideband Open-Ended Ridge Gap Waveguide Antenna Elements for 1-D and 2-D Wide-Angle Scanning Phased Arrays at 100 GHz

A new antenna element type based on the open-ended ridge gap waveguide (RGW) is proposed for beam-steering phased array applications. This element type is of a particular interest at high mm-wave frequencies (≥ 100 GHz) owing to a contactless design alleviating active beam-steering electronics integration. The key challenge addressed here is a realization of a wide fractional bandwidth and scan range with high radiation efficiency. We demonstrate a relatively simple wideband impedance matching network comprised of an aperture stepped ridge segment and a single-pin RGW section. Furthermore, the E- and H-plane grooves are added that effectively suppress antenna elements mutual coupling. Results demonstrate a wide-angle beam steering (≥ 50\ub0) over ≥ 20% fractional bandwidth at W-band with ≥ 89% radiation efficiency that significantly outperforms existing solutions at these frequencies. An experimental prototype of a 1 719 W-band array validates the proposed design concept through the embedded element pattern measurements

W-band Waveguide Antenna Elements for Wideband and Wide-Scan Array Antenna Applications For Beyond 5G

Energy-efficient and highly-compact beam-steering array antennas at W- and D-band frequencies are considered as future enabling technologies for beyond-5G applications. However, most existing solutions at these frequencies are limited to the fixed-beam and frequency-dependent beam-steering scenarios. This paper aims to fill in this knowledge gap by investigating various types of antenna elements as potential candidates for wideband and wide-scan arrays at W-band. We consider open-ended ridge and ridge gap waveguide radiating elements that could overcome the physical complexities associated with the integration of elements in large-scale electronically scanned arrays. An infinite array approach is used, where we have adopted a triangular array grid and introduced E- and H-plane grooves to the element design to enhance the scan and bandwidth performance. Cross-comparison of several simulated array designs leads to the final array elements with 25% impedance bandwidth over the scan range of \ub140\ub0 in both the E- and H-planes

Feasibility Study of a Wide Coverage Dual-Polarized Phased Array Antenna at 10 GHz

The paper studies the feasibility of designing and manufacturing a low-profile, dual-polarized wide-scan X-band (10 GHz) antenna array. In a large array environment, approximated as an infinitely large array, the antenna is capable of beam scanning up to \ub175\ub0 with a bandwidth of 15% in terms of the active reflection coefficient (Γ act ) below −10 dB

Application of the Compressive-Sensing Approach to the Design of Sparse Arrays for SATCOM Applications

Current SATCOM systems employ multiple reflectors with a one-feed-per-beam configuration to synthesize narrow spot-beams. However, these systems are very complex and offer very limited reconfigurability. Active antenna arrays are attractive solutions [1], although are often expensive due to the large number of elements and electronic components involved. Aperiodic array antennas can substantially reduce the number of elements and costs with respect to regular arrays but their design is challenging [2]. Several synthesis methods have been proposed, yet aperiodic array design techniques are not as mature as those in use for their regular array counterparts. These methods are often either: (i) accurate but computationally expensive (e.g. Genetic Algorithms [3]), or; (ii) efficient but simplified (e.g. Density Tapered method [4]). Compressive Sensing (CS) has been recently applied to the synthesis of sparse antenna arrays. The method can optimize large maximally sparse antenna array problems in a fast, deterministic and flexible way [5]. In previous research publications, the authors have (i) extended the original formulation to the multi-beam scenario; (ii) exploited array layout symmetry and modular design; and (iii) hybridized the original iterative optimization procedure with a full-wave EM analysis, so as to include the effects of mutual coupling into the design process and studied for arrays of strongly coupled antennas elements, such as dipoles, as well as large planar arrays of pipe horns [6, 7]. Additionally the authors have addressed multi element type design [8] and, more recently, are investigating reconfigurable arrays (i.e. arrays designed to provide a set of arbitrary-shaped beams) and isophoric arrays (i.e. arrays with a single excitation amplitude). The main directions are summarized in Fig. 1