Attempting to make a balun by coiling coax is a tricky business.
The idea with these baluns is to make an inductor with the coil. Because an inductor has an impedance that increases with frequency, it's hoped they will look like a high impedance to common-mode currents on the coax.
Unfortunately, a real coil also has capacitance between the turns which ...
Having a 50Ω unbalanced output radio feeding a 50Ω unbalanced ground plane antenna through a 50Ω unbalanced coax feeder, there is nothing more you would need to do other than raise the antenna height for improved performance.