NSI-near-far - NEAR-FIELD Any antenna can be successfully...

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Theory NEAR-FIELD 11 Near-field vs Far-field Any antenna can be successfully measured on either a near-field or far-field range, with appropriate implementation. There are significant cost, size, and complexity details which will lead to a recommendation of one type over the other. In general, far-field ranges are a better choice for lower frequency antennas and where simple pattern cut measurements are required, and near-field ranges are a better choice for higher frequency antennas and where complete pattern and polarization measurements are required. Each measurement type has additional sub-types which have certain advantages and disadvantages, and this makes generalized comparisons between near-field and far-field techniques difficult. One common advantage cited for near-field measurement techniques is that testing can be accomplished indoors, eliminating problems due to weather, electromagnetic interference, security concerns, etc. however the same advantages can be quoted for indoor far-field measurements using anechoic chambers and compact ranges. Cost of facility implementation is a critical determining factor in range selection. Far-field ranges are often considered to be less expensive than near-field ranges. When considering the value of the real-estate required for an outdoor far-field range, the situation may reverse. An indoor far-field compact range would typically cost 3-4 times more than a planar near-field range capable of testing the same size aperture, due to the larger chamber size required and cost of the compact range reflectors. The following table summarizes some general tradeoffs to help you in your selection criteria. Many of the characterizations are difficult to make without caveats, and there will certainly be exceptions. Antenna engineers are a creative group and, over the years, have certainly developed innovative ways to maximize the use of their test ranges to get acceptable results. Your NSI sales representative can help you evaluate the tradeoffs further.
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Theory NEAR-FIELD 12 In 1991 Dan Slater wrote a comprehensive book titled "Near-Field Antenna Measurements" about the emerging antenna measurement technique known as near-field measurements. The book derives from Dan’s experience with a variety of near-field measurement systems he designed while a consultant to TRW's Antenna Systems Laboratory and later as NSI’s co-founder. The book is currently undergoing a second publication scheduled for release in 2002. Dan Slater co-founded NSI with Greg Hindman in 1988 after working together for many years at TRW. “Near-field Antenna Measurements” covers many aspects of near-field antenna measurements in a straightforward and consistent way. After many years of development and independent industry evaluation, near-field antenna testing has
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This note was uploaded on 06/07/2011 for the course EE 11 taught by Professor D during the Spring '11 term at Central Lancashire.

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NSI-near-far - NEAR-FIELD Any antenna can be successfully...

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