From: lars@beagle-ears.com   
      
   On 11/12/2025 21:18, Carlos E.R. wrote:   
   >>>> Home made with a box of Pringles. just google for "pringles wifi antenna".   
      
   On 2025-12-24, mm0fmf  wrote:   
   >>> Also Google cutoff frequency and see that the Pringle tube is too small   
   >>> in diameter to be effective at 2.4GHz.   
   >>> Of course, designs on the internet do not have to follow the laws of   
   >>> physics! :-)   
      
   On 25.12.2025 0.53, Lars Poulsen wrote:   
   >> As a wireless applications engineer, I have always shaken my head   
   >> at the pringles can antenna, which if well made can have a gain up   
   >> to at most 8 dBi or so. For less than $50, you can buy a professinally   
   >> made flat patch antenna with 8 dBi gain at L-com.com. Apparently, you   
   >> can find used ones on eBay for under $30, but why take the risk?   
   >> If you need circular polarization, it will be closer to $75.   
      
   On 2025-12-25, Tauno Voipio  wrote:   
   > The range of license-free WiFi is intentionally limited by limiting   
   > the transmit radiation power to any direction to 100 mW EIRP, effective   
   > isotropic radiative power.   
   >   
   > Luckily, in practice, the feedline and active radiator matching losses   
   > take care of EIRP limiting, so the Pringles can stays out of radio   
   > regulation violations.   
      
   As a law-abiding Finn, you are working with EU/ETSI regulations.   
   I work in the US, where the rules are a bit looser, are typically   
   enforced only if someone reports a problem.   
      
   In the US, the maixumum EIRP is 30 dBm (rather than your 20), and   
   if your beam is narrow, it can often be allowed to go to 36 dBm.   
      
   In many 3rd world countries, they may advertize that they follow the   
   US/FCC rules, but they may be no enforcement, so some of our clients   
   have asked us to fit 2 W or 4 W external power amplifiers.   
      
   That said, the benefit of a higher gain antenna is not only that as   
   the beam is focused, you also cut out a lot of the noise in your   
   environment. And the gain applies to the received signal as well   
   as to the transmitted signal. The downside is that you have to do a   
   better job in aiming the antenna, and a windstorm may knock your   
   antenna out of alignment.   
      
   In my professional practice, we have worked with clients in many   
   different environments, from a sewage pumping station in Saudi   
   Arabia to a neutrino detector embedded in the antarctic ice.   
   A white, powder coated aluminum enclosure mounted next to the   
   antenna atop a pole helped keep the radio cool. Our clients in   
   the Antarctic mounted the radio in a heavily isolated box with   
   heater to keep the radio and the lead-acid battery work in the   
   environment where the summer temperature might be -60 degrees   
   Celsius. They got power from solar panels and wind turbines in   
   the summer, and wind turbines in the winter, but everything   
   still went offline for several months every winter, once the   
   storms killed the wind turbines.   
   --   
   Lars Poulsen - an old geek in Santa Barbara, California   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)