Dan Zimmerman N3OX wrote:
>>
>> Sure, a parallel LC circuit (trap) will do it but not a coil alone
>
>
> Not true.
>
> An EZNEC model shows that a 110ft dipole 30 feet above ground* resonates at
> 3.64MHz and 7.13MHz when 39uH coils are added 11 feet from each end. The
> 2:1 SWR bandwidths are narrow (100kHz on 80 and 150kHz on 40) even with
> realistic inductors (Q=100). There is no possibility of stray capacitance
> because in the simulation they're mathematically idealized objects.
>
>
Actually, there is some stray C in your NEC model, because even a thin
wire has capacitance (around 10 pF/meter, as I recall..)
BTW, Medhurst's paper is online at princeton
http://www.physics.princeton.edu/~mcdonald/examples/EM/medhurst_we_35,80_47.pdf
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