The characteristic basis function method (CBFM) has been hybridized with the adaptive cross approximation (ACA) algorithm to construct a reduced matrix equation in a time-efficient manner and to solve electrically large antenna array problems in-core, with a solve time orders of magnitude less than those in the conventional methods. Various numerical examples are presented that demonstrate that the proposed method has a very good accuracy, computational efficiency and reduced memory storage requirement. Specifically, we analyze large 1-D and 2-D arrays of electrically interconnected tapered slot antennas (TSAs). The entire computational domain is subdivided into many smaller subdomains, each of which supports a set of characteristic basis functions (CBFs). We also present a novel scheme for generating the CBFs that do not conform to the edge condition at the truncated edge of each subdomain, and provide a minor overlap between the CBFs in adjacent subdomains. As a result, the CBFs preserve the continuity of the surface current across the subdomain interfaces, thereby circumventing the need to use separate ldquoconnectionrdquo basis functions.

Fast Analysis of Large Antenna Arrays Using the Characteristic Basis Function Method and the Adaptive Cross Approximation Algorithm

This review of array antennas highlights those elements of theory and hardware that are a part of the present rapid technological growth. The growth and change in array antennas include increased emphasis on "special-purpose" array techniques such as conformal and printed circuit arrays, wide angle scanning arrays, techniques for limited sector coverage, and antennas with dramatically increased pattern control features such as low sidelobe, adaptively controlled patterns. These new topics have substantially replaced large radar arrays in the literature and constitute a major change in the technology. The paper presents a tutorial review of theoretical developments emphasizing techniques appropriate to finite arrays, but indicating parallel developments in infinite array theory, which has become the useful tool for analysis of large arrays. A brief review of the theory of ideal arrays is followed by a generalized formulation of array theory including mutual coupling effects, and is appropriate to finite or infinite arrays of arbitrary wire elements or apertures in the presence of a conducting ground screen. Some results of array tolerance theory are summarized from the literature and retained as reference throughout discussions of array component requirements and device tolerance for low sidelobe arrays. Examples from present technology include conformal and hemispherical coverage arrays, lightweight printed circuit arrays, systems for use with reflectors and lenses in limited sector coverage applications, and wide-band array techniques.

/pdf/phased-array-theory-and-technology-vd2kmn6z8c.pdf

Phased array theory and technology

Recent advances in wireless sensing and communications have resulted in the need for antennas capable of high-directivity reconfigurable beamforming. Transmitarrays have been shown to be viable architectures, and two general design approaches have emerged: the layered-scatterer approach and the guided-wave approach. In this paper, we first investigate the beamforming capability of the layered-scatterer approach, generalizing the approach using impedance surfaces. Using Floquet mode analysis, we show that when a structure of this type is used to produce a pencil beam at angles greater than 20 degrees off-broadside, significant side-lobes are produced at large angles, regardless of the aperture size. Next, we present a fully reconfigurable 6 × 6 transmitarray based on a guided-wave approach that experimentally demonstrates both pencil beam scanning over a 100 × 100-degree window as well as shaped-beam synthesis, over a 10 percent fractional bandwidth. The conclusion from our investigations into these two approaches is that for general beamforming applications, the guided-wave approach is superior, achieving good bandwidth, scanning range, insertion loss, and small structure thickness, with only moderate fabrication complexity.

Reconfigurable Transmitarray Design Approaches for Beamforming Applications

In this paper, the scanning performances of connected arrays that include backing reflectors are investigated. The comparison between connected dipoles and slots is based on the properties of the corresponding Green's functions (GFs). The investigation reveals that connected arrays of dipoles are better suited to scan to wide angles (45deg), retaining the minimal number of transmit/receive (T/R) modules. This paper quantifies and motivates this preference. Eventually, the theoretical design of a fully efficient, 40% bandwidth (BW), planar array with the lowest possible cross polarization is presented.

/pdf/scanning-performances-of-wideband-connected-arrays-in-the-3iy1by5a8z.pdf

Scanning Performances of Wideband Connected Arrays in the Presence of a Backing Reflector

Cylindrical array antennas are attractive for applications requiring uniform 360\deg azimuthal pattern performance. For very low sidelobe or precise angle measurement designs, an accurate knowledge of the mutually coupled element pattern becomes important. A modal solution is presented for an element pattern in a periodic array of axial dipole radiators placed coaxially over a circular cylindrical ground. This solution avoids the problems associated with asymptotic appproaches and displays a number of advantages: 1) it is exact, subject only to truncation errors; 2) it is uniformly valid in all spatial regions for both rectangular and, with a simple modification, for triangular isosceles lattice configurations; and 3) it provides absolute gain information. The analysis is presented along with numerical results for representative parameter values, selected to illustrate the various trade-offs. Comparison with published data employing the asymptotic approach and with planar array results is given.

Element pattern of an axial dipole in a cylindrical phased array, Part I: Theory

In this paper we present the design, development and demonstration of an L/S band subarray - a basic building block of a geodesic dome phased array antenna. As previously reported, the geodesic dome array is a highly effective, multi-function, low cost spherical phased array antenna that provides hemispherical coverage. The antenna consists of a number of near-equilateral triangular, planar subarrays arranged in an icosahedral geodesic dome configuration. This novel architecture design preserves all the advantages of a spherical phased array antenna while its fabrication is based on well-developed, easily manufacturable, and affordable planar array technology. The antenna is used for simultaneous, full-duplex communication and control of multiple satellites, and for air/space surveillance over the entire sky.

The geodesic dome phased array antenna for satellite control and communication - subarray design, development and demonstration

In this paper we present design trade-offs of array architectures for hemispherical coverage. We show that a spherical array geometry is the optimal choice for this application in terms of performance and cost. It is a natural array geometry that provides scan-independent hemispherical coverage with a uniform gain pattern. We also show that a spherical array requires fewer elements than a comparable multi-planar phased array with significantly larger instantaneous bandwidths, lower polarization and mismatch losses

Spherical Arrays - Design Considerations

A novel method for the analysis of finite arrays is presented. The method is based on a global array concept where the array problem (for single-mode elements) is reduced to a solution of a single Fredholm integral equation of the second kind. This formulation offers several types of solutions (not all explored yet) with illuminating results. The approximate solution of this integral equation, for example, yields finite array characteristics in terms of equivalent infinite array scattering parameters and mutual admittances. The method is general, i.e., applicable to any element-type and periodic array geometry. Presently, the method applies to single-mode elements (one unknown per element), however, it can be extended to a multimode analysis.

Analysis of finite arrays-a new approach

Transmit/Receive (T/R) module that provides multiple simultaneous ground to satellite links with rapid pointing and acquisition. The (T/R) module incorporates independent gain and phase control. Left-hand or right-hand circular polarization can be supplied to dual feed antennas. Present invention allows each antenna to be independently polarized. Low-cost componentry is utilized throughout. On-board control of the (T/R) module is obtained using a complex programmable logic device (CPLD) and a micro controller. CPLD provided separate control of four phase shifters, attenuators, channel polarization as well as transmitter on/off control. Telemetry is provided through built-in test (BIT) routine.

Boris Tomasic

Papers

Element pattern of an axial dipole in a cylindrical phased array, Part I: Theory

The geodesic dome phased array antenna for satellite control and communication - subarray design, development and demonstration

Spherical Arrays - Design Considerations

Analysis of finite arrays-a new approach

T/R module for satellite TT and C ground link