Text 46177, 53 rader
Skriven 2008-05-24 11:28:00 av MARTIN ATKINS (1:123/140)
     Kommentar till en text av TOM WALKER
Ärende: Broadband.
==================
-=> TOM WALKER wrote to MARTIN ATKINS <=-


 MA>Example Channel 6 midrange = 2437000000 Hz

 MA>4.8432 Inch

 MA>1/4 wave = 4.8432/4 = 1.21" inch.

 MA>Also gives wave in centimeters (cm). :-)
 
TW> That sounds like the typical WiFi stub antenna is a 5/8 wave then.

Oh what a tangled web we weave when radio waves we seek to send and
receive.

My apologies to Sir Walter Scott, author & novelist (1771 - 1832)

I was working on a hotel network that had trouble sending and receiving 
signal to the upper rooms. I suggested they set the router antenna to the 
vertical plain. Most people think that aerials work best in the horizontal
possition. 

A total waste of time. :(

Every time they had drop out I would find that some dumb schmuck
had moved the antenna to the horizontal plain.

Anyway you might find this site useful as it dissects a typical stub router
antenna.

http://martybugs.net/wireless/rubberducky.cgi

It says in part.

The centre core of the coax extends through this crimped join, and becomes
the whip at the top of the antenna.

Each half of the dipole is a 1/4 wavelength, with the length corrected based
on the velocity of the coax being used. Assuming a centre frequency for 
802.11b of 2.441GHz, a 1/4 wavelength in free space is 30.7mm.

However, with this rubber ducky having a 1/4 dipole length of 26mm, we can 
deduce that the velocity factor of the coax used is approximately 0.85 
(ie, the same velocity factor as LMR400 coax, and also confirmed by 
other people's test results). 

Things are never as simple as we would like. ;-) 


 
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