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IEEE Std 1502-2020 pdf free download
IEEE Std 1502-2020 pdf free download.IEEE Recommended Practice for Radar Cross-Section Test Procedures.
To approximate the desired free-space. far-field conditions in an outdoor environment, it is common to separate the source radar physically from the targets with “sufficient separation” in a measurement environment that is free of unnecessary monostatic and bistatic radar clutter. The approximation to a plane wave is obtained by the range length and the approximation to free space by the absence of spurious signals originating from clutter multipath that eventually propagates to the desired test zone as an undesired interference term. The amplitude field taper in the test zone is determined by the radiation pattern of the instrumentation radar; the phase taper is determined by the distance between the radar and the test zone; and the amplitude ripple is determined by interference with the direct signal caused by spurious reflections. In the special case of the ground plane range, which is described in 5.2.2, the amplitude taper in the vertical direction is also determined by the ground-bounce geometry. Givcn surrounding areas that arc free of obstacles, the principal source of contamination to the incident field is the reflection from the ground surface. Consequently, the control of signal reflections from the ground surface constitutes the principal design objective of the range.
Several techniques are used for the control or mitigation of ground reflections. These techniques include utilizing reflecting or absorbing fences to shield the signal path directed to the ground bounce region, elevating the receiving and transmitting antennas sufficiently so that the ground bounce is outside the main lobe of the antenna, using shaped bcrms running the length of the range to deflect the ground reflection away from the test zone, and exploiting the ground bounce by combining with the direct signal in a constructive manner. Each technique is reviewed in 5.2.3 through 5.2.5. In addition to controlling the detrimental effects of ground reflections, significant range-geometry parameters that drive the performance of outdoor ground-plane ranges arc phase and amplitude tapers in the test zone and range clutter, both of which are summarized in the following paragraphs.
For an outdoor range. the rule of thumb that the far field starts at a distance R of 2D 2/A from the transmitting antenna, where D is the maximum dimension of the antenna and A is the corresponding wavelength of the radiated signal. is not universally valid. Abdallah et al. [Bi] and Hansen, Bailin [B27J show that this rule of thumb is only valid for antennas in free space where D>> A and consequently is not applicable for antennas if D is comparable to A. For this condition (D>> A), the antenna pattern in free space closely resembles that of an omni-directional antenna if R< 0.62 (D3/A)’/2 (reactive near field) and begins to take shape if 0.62 (D312)1/2 ≤ R≤ 2D2/2 (radiative near field). Then, when R> 2D2/2. one is in the far field, and the antenna radiation pattern is generated.IEEE Std 1502-2020 pdf free download.
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