What's the difference between a helical antenna and a helical coil?

zero_coke

Joined Apr 22, 2009
294
I'm a bit confused and I would appreciate it if someone could explain the theory behind this: Say you have a helical antenna, one end of the antenna is connected to a coax cable and the other end is just let loose right? Where's the ground connection for this antenna?

And my second question is, say you had the exact same helical coil antenna but you applied a + and - voltage at both ends. Is this the same thing? I mean, do these two (helical antenna & helical inductor coil) produce the same EM fields and whatnot?

I'm asking this because I think what the guys at MIT did for wireless power transfer is they they used two coils but I'm not sure if they're antennas or simple LC circuits where those giant coils were inductors...

bertus

Joined Apr 5, 2008
22,233
Last edited:

crutschow

Joined Mar 14, 2008
33,369
I'm a bit confused and I would appreciate it if someone could explain the theory behind this: Say you have a helical antenna, one end of the antenna is connected to a coax cable and the other end is just let loose right? Where's the ground connection for this antenna?

And my second question is, say you had the exact same helical coil antenna but you applied a + and - voltage at both ends. Is this the same thing? I mean, do these two (helical antenna & helical inductor coil) produce the same EM fields and whatnot?

I'm asking this because I think what the guys at MIT did for wireless power transfer is they they used two coils but I'm not sure if they're antennas or simple LC circuits where those giant coils were inductors...
To transfer power I believe only the magnetic field was used, not the EM field.

zero_coke

Joined Apr 22, 2009
294
To transfer power I believe only the magnetic field was used, not the EM field.
Yes, which is what I'm wondering: Should I be using an antenna in this case or just an oscillating LC circuit? I don't understand...wouldn't it be better to use an LC circuit because it can never radiate harmful E-field since it's confined to the plates of the capacitor only?

Why would anyone want to use the helical antenna instead of a helical coil with a capacitor?