MSGID: <10igrsj$vpf9$1@dont-email.me> c88cc326
REPLY: <10iglir$1086g$2@dont-email.me> 80d8987d
PID: PyGate 1.5.2
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TZUTC: 0000
REPLYADDR jrwalliker@gmail.com
REPLYTO 3:633/10 UUCP
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


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