| For the antenna design you need two located near to each
other heater pipes. The pipes make a substitute open two wire line.
The line is radiated by itself however if you are lucky and the
substitute open two wire line is terminated on something that can
be an antenna (such case is not rare at all) the WHAS will work
Use an ATU with symmetrical output for the design. Other
versa, if you have an ATU with unbalance output, find from experiments
to which tube need to connect the ATU ground. For better work the
WHAS install ferrite rings (5- 20 ring with any permeability) at
two ends of the coaxial cable going from TX to ATU.
Direct Feed WHAS
Direct feed WHAS has efficiency less the two above described
WHAS but this one is very easy to design.
Use direct feed WHAS if you can not use the two above described
WHAS. Fig. 3 shows the design of direct feed WHAS. Design
of the direct feed WHAS is simple. A clamp, which should provide
good electric connection, put on a pipe at any place. An ATU output
is connected to the clamp. A counterpoise of 5- 10 meters in length
is connected to the Ground of the ATU through known device Artificial