<VV> Formula for antenna length

Barry Johnson barry.johnson at activant.com
Wed Sep 2 08:50:46 EDT 2009


> ... how does the speed of light come into play?  What's the formula -
if you happen to know.

The wavelength is the distance between "peaks" of the radio waves.  The
waves are travelling at the speed of light, and the frequency of a radio
station is effectively the number of waves that hit the antenna each
second.

So take the speed of light in inches per second, and divide by the
frequency in cycles per second:

   (186,212 miles/hour * 5280 feet/mile * 12 inches/mile)  /  98 million
cycles/second = 120.4 inches

So the distance between waves for a 98 MHz FM radio station is a hair
over 10 feet.  Your best FM reception would come with an antenna that's
about ten feet long.  But because that's impractical, antenna lengths of
either 1/2 or 1/4 the wavelength are used.

That's where the 30.1 inches for 98 MHz comes in.  (94.7 MHz = about
31.15 inches, btw)

baj
 
 
Notice: This transmission is for the sole use of the intended recipient(s) and may contain information that is confidential and/or privileged.  If you are not the intended recipient, please delete this transmission and any attachments and notify the sender by return email immediately.  Any unauthorized review, use, disclosure or distribution is prohibited.



More information about the VirtualVairs mailing list