Performance Analysis of Antenna Energy Pattern and Its Applications
Date Issued
2010
Date
2010
Author(s)
Liao, Chao-Hsiang
Abstract
Power patterns in the frequency domain are usually used to describe the antenna performance in narrowband communication systems; however, they are not sufficient for ultra wideband (UWB) antennas in wideband communication systems. In this dissertation, energy pattern, energy gain, and energy efficiency are introduced and used to describe the performance of UWB antennas and arrays. Numerical simulations and measurements are used to demonstrate the difference between power patterns and energy patterns for Yagi-Uda antenna, four beams smart antenna array, UWB CPW–fed bow-tie slot antenna, UWB comb taper slot antenna, and four-element UWB comb taper slot antenna array with element spacings of 2.5, 8.5, and 18 cm. The four-element UWB array system with uniform and non-uniform element spacing is analyzed by energy pattern.
Second, a beam scanning technique is developed with a time delay for UWB arrays. In addition, a formulation of the time domain array factor for UWB antenna arrays is presented. An UWB comb taper slot antenna array with large element spacing and impulse excitation are studied and four-element UWB linear array systems with element spacings of 2.5, 8.5, and 18 cm in the broadside direction and 20 degree scanning are implemented.
Finally, the four-element UWB comb taper slot antenna array with 18 cm element spacing is used for real beam radar imaging, the UWB array waveform is an effective way of improving the resolution for microwave imaging. A wideband double ridge horn antenna is used as the transmitting antenna, the above developed large aperture UWB array is used as the receiving antenna. The transmitting antenna and the receiving antenna are combined with impulse time domain measurement system to achieve real beam radar imaging. The receiving impulse signals at various positions are processed by the time delay and sum algorithm. The examples of several aluminum cans will be verified in the resolution of microwave image and compared with transmitting and receiving antennas are using wideband double ridge horn antenna. The results of real beam radar imaging from both simulation and experiment are well agreed. The cross range resolution of UWB antenna array is better than single wideband double ridge horn antenna due to the beam width of UWB array is narrower.
Subjects
energy pattern
energy gain
UWB array
microwave imaging
SDGs
Type
thesis
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