Cb advice

Many Radio Stations use more than 1 tower. One AM station about 5 miles from me has 5 tower in a straight line spaced about 100 yards apart.

As to the length of coax -- I love for some one to explain to me why coax has to be in given lengths.

Leon
kc0iv

 

Many stations have to go directional at night and the towers act as a beam ....

The coax myth has been around since coax was invented if your antenna is matched the coax does not care how long it is ....

 

this is how to phase antennas

 

People who run co-phased are antenna ignorant.

 

I mean you are going directional. Unless that is what you are trying to do, why do it. One antenna ans I talk and hear for miles.

 

FOWARD = FULL SCALE

then go to REFLECTED

What do you read ?

 

The reason for 3 foot lengths of coax is so the over all electrical length of the antenna (which includes the cable) matches the wavelength of the radio. The frequency of the CB signal is 27.4 MHz (somewhere around the middle of the band). The wavelength (in feet) of the CB signal is 36'. A half wavelength is 18' a quarter wavelength is 9' and so on.

 

Some common coax lengths when the freq is 27.4 mhz when you include the VELOCITY FACTOR of the coax.

RG 8 = 23.76 ft - 1/4 wl 8.9 ft
RG-8X = 30.24 ft - 1/4 wl 7.56 ft
RG-58 = 23.76 ft - 1/4 wl 8.9 ft

As you can see the length are way off from the 3,6,9,18, etc. given by the people that make these claims. These people don't include the VF when using these lengths.

A 50 ohm antenna feed by a 50 ohm coax the cable length can be any length.

Leon
kc0iv

 

Don't pay attention to all the coax myths you read online, this coax calculator is all you need to determine the proper length of coax for your setup:

Coax length Calculator ---> Click