Topic
Reflective array antenna
About: Reflective array antenna is a research topic. Over the lifetime, 4366 publications have been published within this topic receiving 57884 citations.
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TL;DR: In this paper, a review of the development of UWB antenna design in the past decade is presented, starting with a brief introduction of the specific requirements and promising applications of UWB systems.
Abstract: The ultra-wideband (UWB) spectrum available for commercial applications has offered us an opportunity to achieve high-speed wireless communications and high-accuracy location applications. As one of key research areas in UWB technology, a lot of innovative broadband and miniaturization techniques for UWB antennas have been greatly invented and developed for years. This paper reviews the development of UWB antenna design in the past decade. Starting with a brief introduction of the specific requirements and promising applications of UWB systems, the unique design challenges of UWB antennas are highlighted. Next, the important milestones of UWB antenna designs are briefed. After that, a variety of planar UWB antennas invented for broadband operation, miniaturization, and multiple functions are introduced. Last, the comments on the development of UWB antennas in future are shared.
15 citations
TL;DR: A combined approach employing low complexity array processing and conventional time-frequency spectrum sensing is proposed towards the detection of space-time white spaces in ω.
Abstract: Space-time spectral white spaces in a cognitive radio environment are defined based on multidimensional spatio-temporal spectral properties of radio waves received by a planar array of antennas. Spectral occupancy of a given carrier frequency pertaining to a particular direction in space is expressed by the volume of a semi-cone shaped geometrical region in the 3-D spatio-temporal frequency space ω. A combined approach employing low complexity array processing and conventional time-frequency spectrum sensing is proposed towards the detection of space-time white spaces in ω. The detection scheme employs four subsystems; antenna array, front-end processing, 3-D spatio-temporal array processing, and 1-D spectrum sensing. Key components in the antenna array and front-end processing subsystems are described including an example of a broadband Vivaldi antenna simulated in the frequency range 1.25-2 GHz. The array processing subsystem employs 3-D infinite impulse response digital beam filters, as a low complexity alternative to conventional phased arrays. One potential realization of the 1-D spectrum sensing subsystem is described by using a tunable bandpass filter followed by an energy detector. Simulation examples are provided by considering different directions of arrival, effect of multi-path replicas, signal to noise ratio changes and both narrow band and wideband signals in the normalized temporal frequency range (0,π).
15 citations
TL;DR: In this paper, a solution for the active impedance and current distribution on a cylindrical antenna in a uniform, infinite, planar, or collinear array is given for the case in which the distance in the collincear direction between the ends of adjacent elements is small.
Abstract: A solution is given for the active impedance and current distribution on a cylindrical antenna in a uniform, infinite, planar, or collinear array. The analysis is applicable to the case in which the distance in the collinear direction between the ends of adjacent elements is small. The current distribution on the collinear array is found by relating the antenna current and electric-field variation on the cylindrical surface of infinite length which contains the array. This analysis is then extended to consider a planar array. Results obtained are applicable to any combination of element length and array phasing, for arrays with or without a ground plane. Comparisons with other investigations based upon sinusoidally distributed currents reveal substantial discrepancies for some configurations.
15 citations
01 Oct 1955
TL;DR: The phase difference between 9,350 megacycle-per-second radio signals received from a common transmitter at two horizontally spaced antennas was measured by the Electrical Engineering Research Laboratory of the University of Texas during March, 1955 as mentioned in this paper.
Abstract: The phase difference between 9,350 megacycle-per-second radio signals received from a common transmitter at two horizontally spaced antennas was measured by the Electrical Engineering Research Laboratory of the University of Texas during March, 1955. The transmitter was located on Cheyenne Mountain in Colorado and the site of the receiver was at Fort Carson, 3.5 miles distant. The elevation angle of the transmitter as seen from the receivers was 9 degrees. This paper presents and discusses the results of these measurements.
15 citations