To calculate the length of wire needed for a 11 meter loop antenna, we must use a formula. Divide 1005 by Frequency in Mhz will give you length in feet.
For example, if we wanted our loop to receive on 27.555 Mhz we would divide 1005 / 27.555 = 36.47 feet or 36 feet, 6 inches.
Before we attach this loop to our 50 ohm coax we need to put a matching section in between the loop of wire and the 50 ohm coax.
This matching section is a section of 75 ohm coax.
(Same as cable tv coax. If you are unsure of the coax's velocity factor, go online and look up the codes printed on the side of that coax first.)
To figure the length of this 75 ohm coax matching section:
This 75 ohm section will be a quarter wavelength of the operating frequency.
To get this we calculate 246 Divided by frequency.
In this case it's 246 / 27.555 = 8.93 feet or approximately 9ft.
Now we need to figure the "Velocity Factor" before we cut this 75 ohm piece.
The velocity factor of your coax is either .66 or .80.
Most RG-59u is .66 so we will use that.
Now take that 8.93 feet from above and multiply that by .66.
For this the answer is 5.89; or 5 feet 10 inches.
If you have .80 velocity factor coax, just multiply 8.93 by .80.
For this the answer is 7.14; or 7 feet 2 inches.