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Re: Terry's New Plane Wave Antenna



Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

Hi,

At 11:25 AM 12/21/2005, you wrote:
Hello Terry,

>The antenna's ground plane is grounded through the cable to
>the scope chassis

I understand this, but - if the scope is grounded directly?

You can ground the scope anyway you want. There should not be a high potential difference between the scope's ground and the coil's secondary ground. Voltage appearing there could foul the readings if it were too high.


And - you wrote:

"If smaller input impedances are available, the frequency response can be extended further"

Pretend a situation - we take, say, an 1M input scope, put the T-connector to its input, 50-ohm terminator and antena to the free side. We`ll lost some sensibility, but I wonder - how much times
would the bandwidth increase? 1000000/50=20000 times?

Yes! If you terminate into 50 ohms, the lower frequency will be devastated. Instead of going to less than say 100Hz you might have a lower cutoff of 2MHz at 50 ohms. It is just a small capacitor and you are loading it heavily, so only very high frequencies will get through.

Cheers,

        Terry



> Original poster: Terry Fritz <vardin@xxxxxxxxxxxxxxxxxxxxxxx>

> Hi,

> The files you mention are up to date.  The antenna will work with any
> scope.  The antenna's ground plane is grounded through the cable to
> the scope chassis.

> Cheers,

>          Terry
.........