Math Q. cuz I'm bored...

Discussion in 'Math' started by mbohuntr, Jun 25, 2009.

1. mbohuntr Thread Starter Senior Member

Apr 6, 2009
430
32
I'm trying to calculate dipole lengths, and I need the calc for wavelength. isn't it 186000(light speed)/frequency?

2. KL7AJ AAC Fanatic!

Nov 4, 2008
2,178
407
yes...but that will give you the antenna length in miles.

A better rule of thumb

1/2 wave dipole= 468/frequency(MHz)

ERic

3. Wendy Moderator

Mar 24, 2008
21,424
2,951
Is the lag included in that number? I thought there was a 95% (or so) difference in the speed of light in a vacumn vs. a wire.

4. beenthere Retired Moderator

Apr 20, 2004
15,808
293
Maybe closer to 96%. The antenna should be 4% shorter (I seem to recall) than the math indicates.

5. ELECTRONERD AAC Fanatic!

May 26, 2009
1,146
16
Or you can do 300/f (in MHz), to find the distance in meters. Yes you are correct, I'm not sure what percentage it really is but we tend to use an antenna analyzer to read the SWR and impedance of the antenna and then usually clip the ends a bit to adjust it.

6. KL7AJ AAC Fanatic!

Nov 4, 2008
2,178
407
yes it is.....in free space it woud be 492

eric

7. mbohuntr Thread Starter Senior Member

Apr 6, 2009
430
32
Awsome! thanks!