Changes

== From Near Fields to Far Fields ==

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== One System for Both Near & Far Field Characterization ==

[[NeoScan]]'s non-invasive electro-optic probes have made it possible to directly measure and map the aperture-level fields of a radiating antenna. When dealing with radiating systems, mapping the near fields can have two different purposes. For the purpose of far-field radiation pattern estimation, you don't want to get too close to the surface of the antenna to avoid picking up all the reactive fields and evanescent modes. If you do so, you will need a rather high spatial resolution to capture the field variations with very precise details. On the other hand, for the purpose of diagnostic near-field mapping, you do need a very high spatial resolution and you want to maintain the field probe as close as possible to the surface of the antenna under test. [[NeoScan]] does both jobs for you and meets both sets of requirements with one system and the same probes.

In short, with [[NeoScan]], you get a compact portable self-contained system that characterizes your antenna system from the very near fields to the very far fields without requiring considerable real estate.

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As the video shows, the low-resolution near-field maps at a higher height above the array surface provide a good estimate of the far-field radiation patterns, but they do not reveal much about the field distribution of the individual radiating elements. To accomplish the latter, you have to bring the probe down much closer to the radiating aperture. From the figures below, you can easily see that a large portion of the supplied RF power is trapped in the feeding transmission lines, and some patch elements receive much lower power levels than the others.

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== A Perfect Solution for Characterizing Ultra-wideband Antenna Systems ==

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.

[[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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== A Perfect Solution for Characterizing High-Power Antenna Systems ==

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.

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