A novel electronically steerable phased array antenna is developed for global positioning system/broadband global area network (GPS/BGAN) navigation applications. The array is composed of 2x2 printed quadrifilar helic...
详细信息
A novel electronically steerable phased array antenna is developed for global positioning system/broadband global area network (GPS/BGAN) navigation applications. The array is composed of 2x2 printed quadrifilar helical antennas (PQHAs) integrated with digital phase shifters for beam steering over the transmit/receive bands. The feed network of each PQHA is based on a sequential rotation to achieve wideband circular polarisation (CP). An elegant control network with the embedded microcontroller is designed to provide driving bits to the phase shifters with reduced phase error. The meandered line design maintains high-performance CP radiation up to +/- 60 degrees off-axis, within 1525 to 1660MHz, and its size is 44% of the design with straight lines. The array gain is positive over 1450-1800MHz beyond the BGAN band, with better than 13dB return loss and <2.2dB axial ratio. The measured broadside gain of the array exceeds 8.5dBi at 1600MHz, and has a wide beam steering of approximate to +/- 80 degrees over the BGAN band. The developed antenna represents a significant technical advance to the design and manufacturing of PQHA array, it has a compact size, low cost and lightweight with a relatively large bandwidth and almost hemispherical coverage with excellent right-hand circularly polarized radiation.
Single beam patterns radiated by linear sources degrade as their maxima points toward endfire direction. Different source geometries are, therefore, to be investigated and compared to achieve better angular coverage. ...
详细信息
Single beam patterns radiated by linear sources degrade as their maxima points toward endfire direction. Different source geometries are, therefore, to be investigated and compared to achieve better angular coverage. We choose to perform this by analyzing the characteristics of the linear operator connecting the current source to the far field in a simplified two-dimensional (2-D) geometry through its singular value decomposition (SVD). Two indexes are introduced and found useful to achieve geometry optimization. First, the case of continuous sources is examined and then the results are extended to discrete (array) sources. It is found that, while the best solution is a conformal semicircumference source, linear sources arranged at angles provide nearly identical single beam patterns pointing in different directions to provide a hemispherical coverage.
Subarray modules are introduced for face arrays used to create 3-D aperture antenna systems. Several representative topologies and major electrical features are reviewed for beam-forming networks of subarray modules. ...
详细信息
ISBN:
(纸本)9781510608719;9781510608726
Subarray modules are introduced for face arrays used to create 3-D aperture antenna systems. Several representative topologies and major electrical features are reviewed for beam-forming networks of subarray modules. Major performance measures such as Gain to Temperature ratio (G/T) are discussed. Three key components are identified and their impact on G/T is studied using circuit models.
Major features and system-level design considerations for 3-D array apertures with hemispherical coverage are presented. First, an ideal 3-D dome-like hemispherical aperture is simulated using physical optics. Second,...
详细信息
ISBN:
(纸本)9781510608719;9781510608726
Major features and system-level design considerations for 3-D array apertures with hemispherical coverage are presented. First, an ideal 3-D dome-like hemispherical aperture is simulated using physical optics. Second, 3-D smooth aperture shape is approximated by several planar facets each presenting identical 2-D aperture arrays. Optimal division of hemispherical field of view into sectors of regards with similar maximum angular scan extent is discussed along with optimization of major electrical features of planar array facets, their number and total component count.
We present a new 2D geometrical technique for determining optimal element arrangement for planar, phased array antennas with specified scan limits. This geometrical technique is not limited to conical or pyramidal sca...
详细信息
We present a new 2D geometrical technique for determining optimal element arrangement for planar, phased array antennas with specified scan limits. This geometrical technique is not limited to conical or pyramidal scanning, but can be extended to any scan type that can be represented with an analytical equation. In addition, simple equations are given for two very important scanning types, conical and pyramidal. These equations provide deeper understanding and simpler graphical solutions than other pure graphical techniques. This paper discusses optimal array arrangement from the viewpoint of general lattice, which itself includes a hexagonal lattice as its subset. An important practical system, where this technique was found to be useful, is the N-face phased array antenna providing scanning throughout a hemisphere. Simple equations are given for determining the maximum off-axis scan and tilt angles of each face with respect to the zenith. Finally, the lattice arrangement of each face is decided by the new design technique.
As more users share the radio spectrum, communications systems become limited by interference. The situation can be improved by using smart antennas, including beam-scanning systems, for increased gain and interferenc...
详细信息
ISBN:
(纸本)9781424402656
As more users share the radio spectrum, communications systems become limited by interference. The situation can be improved by using smart antennas, including beam-scanning systems, for increased gain and interference suppression. The design of beam-scanning arrays typically involves a tradeoff between the coverage (the set of directions over which beams can be directed) and the scan angle. Wide coverage, which is typical for mobile communications, requires large scan angles from single arrays and this results in scan loss and greater cross-polarization which degrade the SNIR. Large coverage angles with low scan loss can only be realized with multi-faceted or conformal arrays. The multi-faceted arrays are simpler to manufacture. For hemispherical coverage, the basic array configurations are the pyramid and the pyramidal frustum. The design for the optimal geometry (face elevation angle) of pyramidal frustum arrays is addressed using a novel minimax-based approach and the methodology for the choice of the number of faces is presented. The coverage is the partial (rotationally symmetric) hemisphere. Applications for these wide coverage array systems are widespread, ranging from fixed and mobile satellite terminals, landmobile vehicular antennas, basestations for indoor and outdoor networks, to radar surveillance and radio astronomy.
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 ...
详细信息
ISBN:
(纸本)078037827X
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 can be used for simultaneous, full-duplex communication and control of multiple satellites, and for air/space surveillance over the entire sky.
暂无评论