From: news@cct-net.co.uk   
      
   On 24/12/2025 23:01, Lars Poulsen wrote:   
   > [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.   
      
      
   Why all this cross-posting?   
      
   --   
   Chris   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)