[BC] Overcrowding & noise floor on AM

[Mark Humphrey]

On 3/19/07, Robert Meuser <Robertm at broadcast.net> wrote:
> That being said,
> to a degree bandwidth can be traded for efficiency. I have done some
> experimentation with 'resistive matching' . It can make a pretty bad
> looking antenna look at lot better. Of course this is at the cost of
> efficiency. This is still somewhat about getting what you pay for.\

How about using a frequency-compensating L-network, with a series LC
in each leg to "track" the base impedance curve?

Grant Bingeman wrote a paper about this technique way back in 1977; he
called it a "bandwidth flattener".  It's a bit more complicated than a
conventional T-network, but offers the transmitter a much flatter
load.  See also his article in the June 78 edition of BM/E.

I was once involved in building an AM station with this type of ATU,
which allowed the transmitter to see a VSWR better than 1.03 across a
20 kHz bandwidth.

Mark