What is the minimum beam width achievable at 50GHz microwave frequency?

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    Beam Microwave Width
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Discussion Overview

The discussion revolves around the minimum beam width achievable at a microwave frequency of 50GHz, exploring the relationship between frequency, beam shape, and antenna characteristics. Participants examine concepts related to beam width in the context of microwave frequencies and antenna design.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant questions the nature of microwave beams, suggesting that they may not have a defined shape and that their shape is inferred from power cutoff values.
  • Another participant confirms that beams are cone-shaped rather than cylindrical and notes that even well-collimated laser beams spread out over distance, with radio signals spreading even more.
  • A participant provides a beamwidth calculator link, indicating that beamwidth is influenced by frequency and antenna type and size, specifically mentioning dish antennas.
  • One participant shares a specific example of a 24GHz signal from a 1-meter diameter dish, stating a -3dB beamwidth of about 4 degrees, illustrating the dependence of beamwidth on frequency and antenna gain.

Areas of Agreement / Disagreement

Participants generally agree on the cone shape of beams and the dependence of beamwidth on frequency and antenna characteristics. However, there are differing views on the conceptual understanding of beam shape and its implications.

Contextual Notes

The discussion does not resolve the assumptions regarding beam shape and the interpretation of beamwidth measurements. The relationship between frequency, antenna design, and beamwidth remains complex and context-dependent.

Delta2
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I guess we all know laser beams. I wonder if we can make beams in the microwave frequency range and how the beam width relates to the frequency, e.g what is the minimum beam width we can achieve with a frequeny of 50Ghz.
 
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I can see beam width is expressed in degrees of an angle and not in units of length. So beams have cone shape and not cylindrical shape afterall? Or (I believe that's the case) is it that they have no shape at all, we just "make up" their shape by considering cutoff values in the power of the field?
 
So beams have cone shape and not cylindrical shape afterall?

yes that's correct. Even a well colluminated laser beam will spread out over a distance
a radio signal even more so

a radio signal beamwidth is usually given ( as you saw) in degrees and to its -3dB ( half power) points either side of the beam centreline. Beamwidth is very dependent on frequency and antenna gain
My 24GHz signal from a 1 metre diameter dish has a -3dB beamwidth of about 4 degrees ( ~ 2 deg either side of the centreline)Dave
 

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