mathamatical furmula for antenna building

[excavator701]

just wanted someone to explain this for me thinking of building a center load coil antenna but wanted to get the correct equation for 26.000 to 28.000 to figure out proper length any help would be great thanks!!!!!!!!!!


</p>

 

[excavator701]

just wanted someone to explain this for me thinking of building a center load coil antenna but wanted to get the correct equation for 26.000 to 28.000 to figure out proper length any help would be great thanks!!!!!!!!!!


</p>

 

[mcjim555]

Hello excavator: the most basic mobil antenna is a quarter-wave vertical for HF-Frequencies (CB-Band) included. The Basic-Formula for a quarter-wave antenna is
( 234 divided by the Frequency in Megahertz) which if your looking for in the middle of 26.000 and 28.000 being 27.000 Megahertz your length will be roughly 8.66 FT. or 103.9 INCHES. BUT you have to take into account the materials your using for the bottom shaft, coil and the top whip. You will also have to take into account your coil diameter, I've built a few of these antennas using wire or tubing for the coil, I usually figure out the total length that I want the antenna to be, then figure the top whip length and bottom shaft length, subtract those from the 103.9 inches and that will give you a rough idea of what your coil length will be. NOW, I "ALWAYS" start out with more material than I figured for the coil length (alot more), it's easier to trim down materials than it is to add some back. Hope this helped, if you have anymore questions you can PM me here on the forum or e-mail me at mcjim555@yahoo.com .....
73 Jim