MSGID:  34be015c   
   REPLY: <10igrsj$vpf9$1@dont-email.me> c88cc326   
   PID: PyGate 1.5.2   
   TID: PyGate/Linux 1.5.2   
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   REPLYADDR lars@beagle-ears.com   
   REPLYTO 3:633/10 UUCP   
   [See also my previous followup - also shifting to alt.   
      
   On 2025-12-24, John R Walliker  wrote:   
   > On 24/12/2025 12:16, The Natural Philosopher wrote:   
   >> On 24/12/2025 07:58, mm0fmf wrote:   
   >>> On 11/12/2025 21:18, Carlos E.R. wrote:   
   >>>> Home made with a box of Pringles. just google for "pringles wifi    
   >>>> antenna".   
   >>>   
   >>> Also Google cutoff frequency and see that the Pringle tube is too    
   >>> small in diameter to be effective at 2.4GHz.   
   >>>   
   >> Assuming that is a relevant issue.   
   >>    
   >> Shouting down a pipe whose diameter is way less than the wavlength of    
   >> voice frequencies, still works....   
   >>    
   >>> Of course, designs on the internet do not have to follow the laws of    
   >>> physics! :-)   
   >>>   
   >>    
   >> ..especially for people who don't fully understand them...   
   >   
   > Indeed.  And I'm sure you are perfectly well aware of the difference   
   > between longitudinal sound waves propagating down a narrow pipe and   
   > transverse electromagnetic waves in a waveguide.   
   > If a Pringles can were highly conductive it would have a cutoff   
   > frequency of close to 2.4GHz so the attenuation would be very high.   
   > However, a very thin layer of aluminium on the inside of a cardboard   
   > tube will be so resistive that it will not make a lot of difference.   
   > For many purposes a well made half-wave dipole or quarter-wave   
   > monopole gives excellent results which are far better than anything   
   > that can be achieved with small pcb antennas.   
   >   
   > A quarter wave monopole made from relatively thick wire or rod can   
   > be an excellent match to 50 ohm coax so long as the ground plane   
   > is at least a few wavelengths across.   
   >   
   > A half-wave dipole combined with a coaxial balun can also be a very   
   > good match but has a slightly narrower bandwidth due to the   
   > frequency dependency of the coax balun.  The choice of which one to   
   > use depends mostly on how the antenna is to be mounted.   
   >   
   > An almost omnidirectional antenna with very low losses can be   
   > more effective than a lossy directional one.   
   >   
   > John   
   >   
      
      
   --    
   Lars Poulsen - an old geek in Santa Barbara, California   
      
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