The Vertical 1-1/4th Wave Ground Plane antenna has a gain of 8dbi over isotropic source. The center conductor goes to vertical element and the outer conductor (braided wire) goes to the horizontal element.
The Vertical Ground Plane antenna impedance averages 50 ohms, and can range from 36 ohms to 84 ohms depending upon the transmission line used. Separation of the center and outer conductor where the coax or other feedline connect should not extend beyond 1" inch.
Vertical antenna's ground elements are always 1/4 wavelength as compared to the driven vertical element. Always mount the Vertical Ground Plane antenna at least it's total length, or greater height above the ground or building for best results.
Note: The 1-1/4th wave vertical ground plane does not need any matching system.
The Formula for a 5/4 wavelength antenna is 1170/frequency in MHz.
The formula for 1/4 ground plane elements is 234/frequency in MHz.
To get the inches instead of a decimal point, just subtract the feet, and multiply 12 times the decimal point left over.
