je me souviens d,avoir entendu des gars (il y a des années) qui justement utilisais ici au Quebec une DDRR en hf mais qui,,,,,,,,,,la je sais plus.
Hé bien, voici un indice. C'est tiré du même eBook dans le chapitre 27 à la page 239:
The DDRR (Direct Driven Ring Radiator) was invented by Dr. Boyer from Northrop, for military applications in the 50s.
VE2DLJ and VE2AMT found some ten years ago an old copy of the 73 Magazine article and decided to build a prototype. They contacted Dr. Boyer and have numerous discussions with him. He warned them and told them “not to cut corners”. His recommendations were:
• Use big tubing: 4 inches or more for 75m.
• Do not use automotive exhaust pipe. It will rust and contacts losses will transform the antenna into a dummy load.
• All contacts and connections must be A1. Solder corners if you make it square, use Penetrox everywhere.
• Use very high voltage vacuum capacitors, and high quality isolators to support the rings.
• No chicken wire. Dr Boyer was horrified by some description of DDRRs using chicken wire. He explained that the Northrop engineers measurements showed that the near field in made of concentric rings in the one ring DDRR and that chicken wire could add losses.
Our two explorers decided to build the antenna following scrupulously all recommendations. Some years ago, Alex, VE2AMT, made a square DDRR for 75m, with special machined metal brackets in the corners so that it could be disassembled if necessary. He adjusted it and worked twoVK and a ZL the first day he used it on the air using 100W.
He explained that listening on this antenna was a real experience. He could hear no noise at all and the DX was Q5 all the time, even when other stations couldn’t copy the DX. The antenna was at that time sitting on the side of his house on wooden blocks 2 feet above the ground.
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