XPost: comp.os.linux.misc   
   From: jrwalliker@gmail.com   
      
   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   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)