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Help designing trap dipole - ARRL Antenna book no help!
The ARRL antenna book describes the inductive effect
of traps on lower freqs and how this physically shortens the antenna. They talk about L/C ratio and give two examples. Problem is they don't give the formula! #$%#%$! Here's my antenna - it's a 75/160 trap dipole. The traps were designed with W8VVM's software. Cutting the 75m portion of the antenna is easy - I need to know how long (as a starting point) to cut the 160 m end pieces! Help! Details: the traps are 8-1/3 turns of rg58 coax wound around a 3-1/2" form. L is 7.211 uH, C is 232.15 pF. X is 176.24 ohms. Design freq on 75 is 3.890. Target freq for 160 is 1.925. I plan on cutting the 75m wires 60.5 feet to start and work up from there but what do I cut the 160m ends to start? Ken KG0WX |
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