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== From Near Fields to Far Fields ==
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[[Image:NEOWEB11.png|thumb|420px|NeoScan field probe scanning the surface of a microstrip patch antenna at 2.4GHz349GHz.]]
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{{#ev:youtube|https://www.youtube.com/watch?v=sjG2aua-4mk|480550|left|'''VIDEO''': Characterizing an S-band microstrip-fed patch antenna using NeoScan.|frame}}
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{{#ev:youtube|https://www.youtube.com/watch?v=l5KjauYge5o|480550|left|<b>VIDEO</b>: Mapping the near-fields of a 64-element X-band patch antenna array with a corporate feed network.|frame}}
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For instance, you can examine the inter-element coupling effects in passive and active phased arrays. The figure below shows a 64-element fixed-beam X-band patch antenna array with an elaborate micostrip corporate feed network operating at 10.65GHz. The array was designed with a uniform amplitude distribution, <i>i.e.</i>, it should supply equal powers to all the 64 patch radiators.
== A Perfect Solution for Characterizing Ultra-wideband Antenna Systems ==
[[Image:NEOWEB28.png|thumb|360px|Measuring the fields at the aperture of an ultra-wideband ridge horn antenna at 5GHz.]]
Far-field characterization of ultra-wideband antenna systems is a very challenging task. Whether you use an anechoic chamber or a conventional near-field scanning system for this task, you have to utilize different types of metallic antennas with different sizes at different frequency bands in both cases. [[NeoScan]] is inherently an ultra-wideband field measurement system. Its EO field probes have cutoff frequencies well within the terahertz region. It is primarily the RF processing back end of [[NeoScan]] that currently limits its operational bandwidth.
<table><tr><td>[[NeoScan]] field probes can measure Image:NEOWEB28.png|thumb|left|420px|Measuring the fields at the aperture field distribution of a wideband antenna over a very large frequency range. However, far-field radiation patterns are frequency domain data by nature. They are measured and visualized at a specified frequency. Several radiation pattern plots are typically generated at different frequency bands to characterize an ultra-wideband ridge horn antenna systemat 5GHz. Using a [[NeoScan]] system for this purpose provides the ultimate convenience of using the same measurement setup, the same AUT positioning and the same field probes to perform near-field scanning at multiple frequency bands. All you need to do is vary the frequency of the RF signal generator that feed the antenna under test. </td></tr></table>
[[NeoScan]] field probes can measure the aperture field distribution of a wideband antenna over a very large frequency range. However, far-field radiation patterns are frequency domain data by nature. They are measured and visualized at a specified frequency. Several radiation pattern plots are typically generated at different frequency bands to characterize an ultra-wideband antenna system. Using a [[NeoScan]] system for this purpose provides the ultimate convenience of using the same measurement setup, the same AUT positioning and the same field probes to perform near-field scanning at multiple frequency bands. All you need to do is vary the frequency of the RF signal generator that feed the antenna under test.
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[[Image:NEOWEB29.png|thumb|left|375px|The aperture field distribution of the ridge horn antenna.]]
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[[Image:NEOWEB30.png|thumb|left|345px|The far-field radiation pattern of the ridge horn antenna.]]
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== A Perfect Solution for Characterizing High-Power Antenna Systems ==
{{#ev:youtube|https://www.youtube.com/watch?v=oAa-XqE9H1g|380|right|<b>VIDEO</b>: Characterizing an X-band slotted waveguide array.| frame}}
Test and evaluation of high-power antenna systems or active phased arrays is a daunting process. Special considerations must be taken into account when measuring high-power radiating systems in an anechoic chamber including operator's safety and fire hazards. The problems are multiplied when using a near-field scanning system whose metallic receiver probe has to be positioned at a far enough distance from the transmitting antenna under test. In contrast, [[NeoScan]] probes can handle field intensities as large as 2MV/m and can even withstand higher radiated power levels. The non-invasive EO probes can be placed very close to the surface of the high-power radiating aperture, while the optical mainframe and RF processing back end reside much farther at a reliable distance from the aperture.
You can use [[NeoScan]] for measurement of different types of antenna structures and array topologies<table><tr><td>{{#ev:youtube|https://www. In certain cases, prior physical knowledge of field distributions may facilitate and expedite the scanning processyoutube. For example, the figure below shows com/watch?v=oAa-XqE9H1g|550|left|<b>VIDEO</b>: Characterizing an X-band slotted waveguide array operating at 9.4GHz. From the physics of such structures, you know that the fields are highly localized close to the centerline of the waveguide array. In addition, the tangential field component parallel to the direction of the slots is zero. Therefore, if the goal of near-field scanning is to compute the far-field radiation patterns, only one tangential field component needs to be mapped. For a complete near-field characterization, however, you may want to measure the normal field maps, too. | frame}}</td></tr></table>
You can use [[NeoScan]] for measurement of different types of antenna structures and array topologies. In certain cases, prior physical knowledge of field distributions may facilitate and expedite the scanning process. For example, the figure below shows an X-band slotted waveguide array operating at 9.42GHz. From the physics of such structures, you know that the fields are highly localized close to the centerline of the waveguide array. In addition, the tangential field component parallel to the direction of the slots is zero. Therefore, if the goal of near-field scanning is to compute the far-field radiation patterns, only one tangential field component needs to be mapped. For a complete near-field characterization, however, you may want to measure the normal field maps, too.
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[[Image:NEOWEB15.png|thumb|left|550px|Measuring the fields at the aperture of an X-band slotted waveguide antenna array at 9.4GHz42GHz.]]
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[[Image:NEOWEB8.png|thumb|left|240px|The aperture field distribution of the slotted waveguide array.]]
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[[Image:NEOWEB16.png|thumb|left|240px|The far-field radiation pattern of the slotted waveguide array.]]
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