Well I learnt how to do Bessel functions 40 years ago!
But today, who knows, I think Lipitor took some brain cells.
Go ahead with the complex variables..
I could be the lost son of the square root of minus one!
73
hank wd5jfr

"John Smith" wrote in message
...

"Henry Kolesnik" wrote in message
...
In the Feb. 2004 QST there's an article by AD5X for a mobile antenna
using
a
Hamstick or Bugcatcher with shunt capacitor feed or an L match. Can
someone
please explain, including the math, on how a ~500pf capacitor transforms
10
ohms to 50 ohms for 40 meters? I get no understand from reading either
my
ARRL Handbook or ARRL Antenna Handbook. There are no stupid questions,
only
stupid people asking!
tnx
hank wd5jfr


Hi, Hank -

If you have a low value resistor and you want to make it appear to your
source to be a higher value resistor, you can add a series resistor or
reactance. If you add a resistor, it will use up some of the available
power
which you intended for the original resistor. So, you use a series
reactance
instead. The only problem is that you now have some (usually) undesirable
reactance to contend with. But, you can get rid of the series reactance by
adding a shunt reactance of the opposite type. That is, if you added a
series capacitor, you can put in a shunt inductor to compensate. Note that
you could have added a series inductor and compensated with a shunt
capacitor. Which one you use is a matter of convenience sometimes.

Before I go into the math, I should ask if you are comfortable with
complex
variables. You know, complex conjugate, R+jX and all that stuff? Besides,
the delay will give someone else an opportunity to put in something I've
missed or messed up. There are a lot of very knowledgeable guys on this
group, you know.

John