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ANTENTOP- 01- 2005, # 007  

Building Antennas



Figure 1   WHAS used gamma matching


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 very efficiently.


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 Ground.’




Figure 2  Two Wire Line WHAS

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August 3, 2016 16:43

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