In p7jpc05ugaf983cn5th32r7rd99cgvbh71@2355323778, Lancer
wrote:

snip
Wrong, the coil has very little radiation. The open air coil has less
loss because the losses are less in an open air coil.
(resistive losses, capacitive coupling losses, form loss)
Do a search on coil Q

Care to argue that point?


I would. What happens when you bring a solid sheet of conductive
material close to the end of a coil? Eddy currents -- it has
tremendous losses, the Q drops like a rock, and it's inductance is
unpredictable. It's a royal bitch to design a shielded IF/RF coil or
transformer to be used for high frequencies, and shielding is almost
-never- used for power RF coils and transformers unless there is some
serious space between the inductor and shield, hence the popularity of
toroid cores for those applications. And since a bigger coil makes a
bigger field, you need much more 'free space' to maintain a high-Q.
Vertically mounting a big coil above the sheet metal of a vehicle
results in a very lossy coil.



4) A stainless steel antenna is less efficient than a copper antenna
of the same length.

not if its electrically shorter than the stainless one

Electrically shorter? You meant physically shorter. I can take a 18
foot antenna and make it electrically shorter than 9 feet while still
keeping it 18 feet long. dumbass


The difference between copper and stainless steel is not very
significant at 27 MHz. What -is- significant is that bare copper will
quickly form a layer of corrosion (visible or not) which will render
an excellent conductor useless for RF. So unless you are willing to
polish and degrease the antenna every day, I'll take the stainless.






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