Maximum Theoretical Angular Accuracy of Planer arrays

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Discussion Overview

The discussion centers on the maximum theoretical angular accuracy of planar arrays of sensors, particularly in relation to the angle of incidence of incoming rays. Participants explore how this angle affects accuracy and resolution, referencing a specific paper for context.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant questions whether the angle between the incoming ray and the normal direction to the planar array influences accuracy, suggesting that maximum accuracy occurs at a 90-degree angle.
  • Another participant discusses the geometric implications of the angle of incidence, noting that as the angle moves off broadside, the apparent extent of the array decreases, which negatively impacts angular resolution and signal-to-noise ratio (SNR).
  • This participant also mentions that the electrical gain of the array decreases more rapidly than cos(θ) due to mismatches in antenna elements, complicating the relationship between angle and accuracy.
  • A follow-up response seeks to clarify the previous points, proposing that the best accuracy and resolution for a planar array occur when the incidence ray is aligned with the normal direction, and that these metrics vary with different angles of incidence.

Areas of Agreement / Disagreement

Participants express differing views on the impact of the angle of incidence on accuracy and resolution, with some agreeing on the general principle that maximum accuracy occurs at normal incidence, while others elaborate on the complexities involved. The discussion remains unresolved regarding the specific implications of these angles.

Contextual Notes

The discussion references a specific paper for theoretical backing, but participants have not fully explored its content. There are assumptions about the relationship between angle of incidence and accuracy that may require further clarification or validation.

Who May Find This Useful

Researchers and practitioners in sensor technology, antenna design, and related fields may find this discussion relevant, particularly those interested in angular resolution and accuracy in planar sensor arrays.

senmeis
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Hello,in this link http://dtic.mil/dtic/tr/fulltext/u2/a028054.pdf a paper „Maximum Theoretical Angular Accuracy of Planer and Linear Arrays of Sensors“ can be found.The accuracies are given in equations 19 (respect to the x axis) and 20 (respect to the y axis).My question is: Shall the angle between the incoming ray and the normal direction to the planar array also play a role? I mean, the 90 degrees angle (along the normal direction) shall have the greatest accuracy. In example of line array on page 15 this angle (15 degrees there) is considered. Do I understand it correctly?Senmeis
 
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I haven't read your link, but I can make some general comments about angular resolution. As the angle of incidence moves off of broadside, the apparent extent of the array normal to the incoming wave shrinks by cos(θ), due to simple geometry. This has two effects. First, the angular resolution suffers since it varies inversely proportional to the aperture length. Second, the SNR drops for the same reason. In fact, the electrical gain of the array drops more quickly than cos(θ) because the antenna elements become mismatched (no longer 50 ohms, e.g.) due to varying phase shifts in the mutual antenna coupling terms as the angle increases. It is common to approximate the rolloff in antenna gain (hence SNR) as cos(θ)^1.5, though this is just an approximation. Both of these effects will reduce the resolution and accuracy.
 
Thank you. Can I understand what you are saying as following in simple words?1. For a planar array the best accuracy and resolution can only be achieved if the incidence ray is on the normal direction.

2. The accuracy and resolution are different with different directions of incidence (different elevation and azimuth angle).Senmeis
 
I'll need to look at that paper...
 

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