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Linear-to-circular polarizers operating at mm-wave frequencies with multiple octaves of bandwidth are reported. First, a polarizer constructed from cascaded anisotropic dielectrics is discussed. This polarizer scales the design of achromatic waveplates from optical frequencies down to mm-wave frequencies. In addition, the polarizer is constructed from artificial dielectrics (metamaterials) rather...
As known, element patterns of large planar arrays can be calculated from an infinite array approximation using a Floquet unit cell approach. For large conformal arrays, however, unit cell methods can't be used, and element patterns must be calculated numerically by solving the full boundary value problem, leading to a prohibitively large number of unknowns. In this work we describe a novel method...
A common way to determine the electromagnetic properties of dielectric materials is to insert a sample of the material into a waveguide and measure the resulting reflection and transmission, i.e. the S-parameters. From the S-parameters the complex permittivity, e can then be extracted by use of various inversion schemes/algorithms, such as Nicolson-Ross-Weir (NRW) method. However, the NRW method is...
A sparse trifilar antenna can support two independent beams while, to reduce the interference between the beams, each array element supports only one beam. To minimize the grating lobe effects each beam is formed by three spiral arms resulting in a sparse random array arrangement. In this paper we investigate the impedance and radiation characteristics of such an array. We have shown that the active...
A sparse trifilar antenna can support two independent beams while, to reduce the interference between the beams, each array element supports only one beam. To minimize the grating lobe effects each beam is formed by three spiral arms resulting in a sparse random array arrangement. In this paper we investigate the impedance and radiation characteristics of such an array. We have shown that the active...
This paper presents the design, development, theoretical and measured results of Digital Beam Forming (DBF) hardware for use with a large, multi-beam conformal phased array antennas such as the Geodesic Dome Phased Array Antenna (GDPAA) shown in Figure 1[1]. The GDPAA system with DBF on receive can provide multiple simultaneous links for satellite tracking, telemetry, and command (TT&C) functions...
A method for in situ evaluation of the health and status of individual array elements within a large phased array has been developed and demonstrated at the subarray level. The technique utilizes a special radiating element located in the center of each subarray. This center element is fed with a “reverse” T/R module that operates in the opposite sense of the regular elements in the subarray; that...
A metamaterial slab of Wire-Split Ring Resonators was analyzed focusing on physical aspects. Effective constitutive parameters were extracted vs. number of W-SRR layers in the slab. We have shown that a minimum of 8 layers is required to accurately characterize the bulk metamaterial properties. Losses, spatial dispersion, and mode conversion in the unit cell are also discussed.
An S-band, full-duplex, multi-channel, transmit/receive (T/R) module has been designed, developed, and produced in large quantities for phased array satellite ground station applications. The satellites, in LEO, MEO, and GEO orbits, need a global network of such stations to serve as gateways for tracking, telemetry, and command (TT&C) operations and/or payload data routing. The array provides...
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