The ZS6BKW antenna is a better match for our bands than the G5RV. The method of construction and tuning is essentially the same for both antennas but the dimensions are different.
Here is the ZS6BKW antenna installed at AK6R fine tuned for the CW/FT8 frequencies on 40-20-17-12-10 meters. An excellent antenna when installed at 30 feet or higher and no tuner required avoiding the tuner losses and constant retuning. If you want to work all bands from 80-10 install an antenna tuner between the 1:1 balun and the amplifier and ignore the 39/40 switch.
Is this the best FT8 antenna? – I think so as I has made over 70,000 contacts and it still is a proven winner -Good world wide DX, easy to install, no tuner and takes full legal limit.
Here are several different 1:1 baluns you can use depending on power requirements:
Use for 3/8″ Cable – RG-8X, LMR-240, etc
For 3/8” cables use five FSB31-3/8 split beads for 80-10 meters (3-30 mHz) or ten FSB-3/8 split beads for 160-10 (1.8-30 MHz) meters or use 15 FSB31-3/8 for even higher choking for 1-10 MHz.
Typical Impedance per split bead: 10 MHz: 100 ohms, 25 MHz: 163 ohms, 100 MHz: 275 ohms, 250 MHz: 275 ohm
Minimum recommended total impedance is 500 ohms at frequency of interest.
The beads clamp to the cable and may be operated as is for indoor use. However, it is strongly suggested that they be covered to protect the plastic covers from weathering – use electrical tape for best results or heat shrink to ensure longer life. All kits come with instruction manual which covers assembly and application tips.
As you can see from the impedance vs frequency graph, you can very effectively increase the choking impedance by increasing the number of beads on the cable.
Here is the Coax Noise Filter used to suppress coax common mode currents (works for all type of antennas)
PDF of ZS6BKW at AK6R Construction Article HERE: My ZS6BKW Antenna