[Antennaware] Negative Impedance Converter NIC

[Terry Conboy]

  On 2010-09-13 11:38 AM, Andy Ikin wrote:
> Is it possible to use NIC to overcome losses in terminated loop antennas? If so, how would one measure the NIC input impedance with say a Signal Generator and an Oscilloscope to check for correct NIC performance?       Andrew Ikin  G8LUG
Andrew,

It seems like you could put a resistor of the design "-R" value in 
series with the input of the NIC and check for a short circuit.

If you're thinking of using this to cancel the resistive load in a Flag 
or K9AY, it would probably produce the same results as just removing or 
lowering the resistor.  Of course, since the resistor sets the current 
magnitude in the loop, the antenna pattern wouldn't be the same.  But 
knowing how inventive you are, you probably had something more clever in 
mind!

I think those NIC circuits were first used in telephony to counteract 
the losses in copper lines.  Using them as -C generators is a neat 
scheme for making wideband matched antennas.  Years ago, early in my 
engineering career, I designed wideband amplifiers with lots of negative 
feedback for linearization, and they often developed negative input 
resistance that sometimes had strange side effects.

73, Terry N6RY