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Ultrasparse, ultrawideband time-steered arrays.
Connect to full text Available online
View online- Format:
- Book
- Thesis/Dissertation
- Author/Creator:
- Schwartz, Jodi Lisa.
- Language:
- English
- Subjects (All):
- Diagnostic imaging.
- Radiology.
- Electrical engineering.
- Biomedical engineering.
- 0541.
- 0544.
- 0574.
- Penn dissertations--Electrical engineering.
- Electrical engineering--Penn dissertations.
- Local Subjects:
- Penn dissertations--Electrical engineering.
- Electrical engineering--Penn dissertations.
- 0541.
- 0544.
- 0574.
- Physical Description:
- 158 pages
- Contained In:
- Dissertation Abstracts International 57-11B.
- System Details:
- Mode of access: World Wide Web.
- text file
- Summary:
- In a high resolution imaging system with a fixed number of array channels, highly thinned or sparsely filled arrays can reduce the quantity of electronics supporting the array, reduce the data-handling requirements, greatly enlarge the aperture, and correspondingly improve its resolving power. In conventional narrowband (NB) array thinning, the cost of using fewer array elements is a dramatic increase in the side energy level. However, ultrawideband (UWB) arrays can significantly reduce this side radiation level. UWB arrays are available because current technology in ultrasound and electromagnetics is now able to construct radiating array elements that can transmit a high energy pulse of only two or three cycles. In a highly thinned UWB array, the distribution of side energy is very different from conventional NB arrays. Due to the UWB nature of the pulse, the radiated waveform in space varies in time. As a result, the waveform has an extra dimension of time, with respect to an NB waveform, across which undesired side energy can be distributed. This extra degree of freedom enables UWB arrays to be highly thinned and achieve a much lower side energy level than NB arrays. An ultrasparse UWB array is capable of reducing the number of elements required by an NB array to approximately the square root of that number ($\rm\sqrt N$ array).
- This dissertation presents a method for characterizing ultrasparse UWB one- and two-dimensional arrays. The analysis begins with a thorough investigation of one-way ultrasparse UWB beampatterns. Contrary to conventional NB wisdom, this analysis shows a periodic configuration of elements to be preferred over a random configuration. This is because grating lobe energy fails to build up coherently off-axis when the array is UWB. Based on this result, guidelines are presented for designing an ultrasparse transmit and receive UWB array system which produces a pulse-echo beampattern that achieves high resolution and a very low side radiation level. Experimental analysis is provided to demonstrate the analysis.
- Notes:
- Thesis (Ph.D. in Electrical Engineering) -- University of Pennsylvania, 1996.
- Source: Dissertation Abstracts International, Volume: 57-11, Section: B, page: 7145.
- Supervisor: Bernard D. Steinberg.
- Local Notes:
- School code: 0175.
- ISBN:
- 9780591205589
- Access Restriction:
- Restricted for use by site license.
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