Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"Directional Antenna"”.
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Enhancing the energy efficiency of ultra wideband (UWB) based media access control (MAC) protocols in mobile ad-hoc networks (MANETs) through the use of steerable directional antenna
… in Mobile Ad Hoc Networks (MANETs). The use of directional antennas can conserve energy due to the increased gain and directed transmission towards specific point in space. Directional antennas also resolve many issues associated with interference from different points within the network. …
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A statistical ultra wideband indoor channel model and the effects of antenna directivity on multipath delay spread and path loss in ultra wideband indoor channels
… three different transmitter/receiver (Tx/Rx) antenna combination pairs. The effects of antenna directivity on path loss and multipath propagation in the channel were analyzed extensively for various omni-directional and directional antenna combinations. A statistical model of the path loss in …
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Directional Communications to Improve Multicast Lifetime in Ad Hoc Networks
… Previous work has investigated the use of directional antennas as a method to reduce inter-node power requirements. However, most proposed methods ignore inter-session interference, propose heuristic solution methods, and ignore the use of directional antennas for signal reception. We …
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Augmenting Wireless Security Using Zero-Forcing Beamforming
… and the upcoming 802.11ac standard where multi-antenna APs construct simultaneous data streams using Zero-Forcing Beamforming (ZFBF). Instead of using this technique for simultaneous data stream generation, STROBE utilizes ZFBF by allowing an AP to use one stream to communicate with an intended …
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Small scale antenna diversity as a means of reducing the effects of multipath fading for handheld satellite communications systems
… communications system using an omni-directional antenna. A significant finding was that motion of the satellite could induce fades of up to lOdB, well in excess of the small link margins available to satellite-to-handheld systems (typically ≤ 3dB). A method for ameliorating multi path …
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Design of a folding antenna-integrated micro UAV
… a device that will be used for high altitude antenna calibration. Such a UAV requires that an omni-directional antenna be integrated into the frame of the device to reduce signal interference. The device is to fold into a flare cartridge and withstand high deployment forces out of an aircraft. …
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Radiolocation using AM broadcast signals
… uncertainty. Since the error in published antenna positions sometimes exceeds 100 meters, I conducted sub-meter-accuracy geodetic surveys of 29 Boston-area AM-broadcast antennas. The directional radiation patterns of the array antennas of many AM broadcast radio stations have phases that …
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Electronic warfare asset allocation with human-swarm interaction
… 3D-spatiality, center frequency assignment, and antenna azimuth and elevation orientation, with respect to power coverage at the receiver without overloading the feed-horn, maintaining suficient power sensitivity levels, and maintaining terrain constraints. Further complexities result from the …
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RF and GIS: Field Strength Prediction for Frequencies between 900 MHz and 28 GHz
… with the higher frequencies require a more directional antenna and are therefore less sensitive to multipath interference. In addition, the smaller wavelengths are less able to diffract around buildings and terrain features.
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Design and Detection Process in Chipless RFID Systems Based on a Space-Time-Frequency Technique
… chipped tags, an integrated IC attached to the antenna is biased by an onboard battery or interrogating signal. Compared to barcodes, the chipped tags are expensive because of the existence of the chip. That was why chipless RFID tags are demanded as a cheap candidate for chipped RFID tags and …
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High Probability of Hiding (HPH) and Quality of Autonomy (QoA) Orientated 3D Transformative Intelligent Routing for Airborne Networks
… Particularly, an AN equipped with the latest antenna technology, called multi-beam directional antenna (MBDA), is mainly considered. MBDA allows the simultaneous packet delivery in multiple directions without RF interference among the antenna beams. We have found that MBDAs can actually bring …
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Direction of arrival estimation for spinning antenna based electronic intelligence systems
The spinning directional antenna is the most cost-effective antenna configuration for providing high gain over a wide (multi-octave) radio frequency (RF) range. Thus, it is the appropriate antenna configuration for increasing the intercept range of an electronic intelligence (ELINT) system, which …
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Design of an HF transmit antenna for bistatic ionospheric soundings in Antarctica
… was to design a suitable transmitter antenna such that propagating skywave signals could successfully be received by the SANAE SuperDARN radar some 2090 km away. A transmitter beacon with an operating frequency of 12.57 MHz and a maximum 1 W power output has already been designed …
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Link Establishment in Ad Hoc Networks Using Smart Antennas
… networks have been designed for nodes using omni directional antennas. Through the use of directional antennas, it is possible to obtain higher efficiency. In this thesis we investigate the impact of these antennas on aggregate throughput and end-to-end delay. The use of omni-directional antennas …
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Some Optimization Problems in Wireless Networks
… n randomly located nodes, each equipped with γ antennas and a rate of W on each data stream, the achievable throughput of each node is Θ(γW/√<span style="text-decoration:overline;">Â n ln n</span></span>). <b>3. Toward Simple Criteria for Establishing Capacity Scaling Laws.</b> Capacity scaling …
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Modeling and design of near-field antennas with periodic structures
… modelled and adopted in the design of near-field antennas. First, the discontinuous Galerkin time-domain (DGTD) method is applied to model the scattering from periodic structures. The modelling of dispersive media is incorporated into a three-dimensional DGTD scheme, which is capable of studying …
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UAV-Enabled Wireless Communications: Deployment, Optimization, and Analysis
… problem of finding an optimal 3D placement and antenna orientation for mmWave-equipped UAVs to minimize the number of required UAVs while maximizing the signal-to-noise ratios (SNRs) to all users. Our approach formulates this as an integer linear programming (ILP) optimization problem, …