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Link analyses and LPD/AJ strategies for IEEE 802.16aWong, Yi Jim 12 1900 (has links)
Approved for public release; distribution is unlimited. / In military operations, covertness of operation is of paramount importance. The transmission power
of the data link must be kept to the minimum to maintain a low probability of detection (LPD) from the
adversary. However, a reduction in the transmitted power implies a reduction in the operating range,
though the detection range by the enemy is also reduced. Therefore, to reduce the enemy’s detection
range while maintaining operating distance, this thesis explores strategies to discriminate gain against an
adversary’s sensor. The strategies involve using processing gain, directional antennas, polarization and
the natural environment as a transmission shield.
The processing gain strategy analyzed in this thesis uses a diversity technique called Maximal
Ratio Combining (MRC) applied to an IEEE 802.16a link. Sinclair D. Smith carried out a study on the
possible processing gain derivable from this technique and this thesis will bring his results to practical
applications via link analyses.
In the event that the link is detected and the enemy decides to carry out jamming, the thesis explores a
possible anti-jamming (AJ) strategy by using MRC and a directional antenna. Daniel P. Zastrow carried out
a study on the AJ capability of MRC and this thesis brings his results to practical applications via link
analyses. / Major, Republic of Singapore Airforce
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ULTRA-WIDEBAND PLANAR ANTENNA DESIGNS AND APPLICATIONSSu, Saou-Wen 22 May 2006 (has links)
The studies in this dissertation mainly utilize planar antennas for ultra-wideband antenna designs not only on the investigation of antenna performance but also towards exploiting attractive features of ultra-wideband antennas for practical applications, such as WMAN access-point antennas, omnidirectional WiMAX access-point antennas, band-notched UWB (Ultra-wideband, 3.1 ~ 10.6 GHz) antennas, and so on. To begin with, the effects of the ground-plane size and the asymmetrical ground plane on ultra-wideband antennas are studied in Chapter 2. Following up, from the conclusive results, an antenna for WMAN operation in access-point applications and an omnidirectional monopole for USB wireless network card device are proposed and analyzed. Characteristics of ultra-wideband antenna radiation in relation to the antenna's width for obtaining omnidirectional radiation are addressed. In Chapter 3, several ultra-wideband access-point antennas are presented for achieving good omnidirectional radiation in the azimuthal plane across the bandwidth. Furthermore, in Chapter 4, band-notching techniques are applied to ultra-wideband antennas for avoiding the interference between the UWB and the WLAN systems.
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