Hi,

If EZNEC reports a source impedance for a balanced antenna, such as
a loop, of R+-jX ohms, and I am trying to match the antenna to the
line: I am using a Smith Chart program that is unbalanced i.e.
everything is respect to ground. Question is, what impedance do I
enter into the program such that I will get the correct matching
solution for the balanced antenna? I have used this program numerous
times and it works well for verticals, mobiles, and other unbalanced
antennas. Thanks.

Gary N4AST

wrote in message
oups.com...
Hi,

If EZNEC reports a source impedance for a balanced antenna, such as
a loop, of R+-jX ohms, and I am trying to match the antenna to the
line: I am using a Smith Chart program that is unbalanced i.e.
everything is respect to ground. Question is, what impedance do I
enter into the program such that I will get the correct matching
solution for the balanced antenna? I have used this program numerous
times and it works well for verticals, mobiles, and other unbalanced
antennas. Thanks.

Gary N4AST


Hi Gary

Is it practical for you to use a Smith Chart rather than a "Smith Chart
program"? A Smith Chart doesnt concern itself with ground. It is mearly
a plot of all possible R+/-jX with real R.

Jerry

wrote in news:1177712640.116329.181210
@o40g2000prh.googlegroups.com:

Hi,

If EZNEC reports a source impedance for a balanced antenna, such as
a loop, of R+-jX ohms, and I am trying to match the antenna to the
line: I am using a Smith Chart program that is unbalanced i.e.
everything is respect to ground. Question is, what impedance do I
enter into the program such that I will get the correct matching
solution for the balanced antenna? I have used this program numerous
times and it works well for verticals, mobiles, and other unbalanced
antennas. Thanks.

Gary,

The impedance transformation is unaffected by whether the load is
balanced or unbalanced. The Smith chart solution does not depend on
balance or not, nor does the underlying maths.

Having said that, if you intend including a balun, you could treat it
simply as an ideal n:1 impedance ratio transformer, dividing the load
impedance at the appropriate point by n... though that may splitting your
Smith chart solution into two parts each side of the transformer (if n!=
1). Some Smith chart software allows specification of a transformer as a
system element, so it is real easy and all displayed on one map.

If you don't want to treat the balun as ideal, my view is that you really
need to include the balun and a path for common mode currents in your NEC
model, because they are actually couped to the radiator and form part of
the system load.

Owen

On Apr 27, 3:24 pm, wrote:
Hi,

If EZNEC reports a source impedance for a balanced antenna, such as
a loop, of R+-jX ohms, and I am trying to match the antenna to the
line: I am using a Smith Chart program that is unbalanced i.e.
everything is respect to ground. Question is, what impedance do I
enter into the program such that I will get the correct matching
solution for the balanced antenna? I have used this program numerous
times and it works well for verticals, mobiles, and other unbalanced
antennas. Thanks.

Gary N4AST


The impedances will still be the same. If you want to keep things
balanced, though, split any series elements into two equal parts. For
example, if your program says to use 20pF in series, use 2 40pF caps,
one on each side, to keep things balanced. With an inductance, use
two inductors that are half as large as the single one. The idea is
the two caps in series or the two inductors in series make the
specified net capacitance or inductance. With shunt elements, there's
no need to do that, just don't ground either side---the shunt elements
go across the balanced network from one side to the other.

Cheers,
Tom

On Apr 27, 5:54�pm, K7ITM wrote:
On Apr 27, 3:24 pm, wrote:

Hi,

* If EZNEC reports a source impedance for a balanced antenna, such as
a loop, of R+-jX ohms, and I am trying to match the antenna to the
line: *I am using a Smith Chart program that is unbalanced i.e.
everything is respect to ground. *Question is, what impedance do I
enter into the program such that I will get the correct matching
solution for the balanced antenna? *I have used this program numerous
times and it works well for verticals, mobiles, and other unbalanced
antennas. *Thanks.

Gary N4AST

The impedances will still be the same. *If you want to keep things
balanced, though, split any series elements into two equal parts. *For
example, if your program says to use 20pF in series, use 2 40pF caps,
one on each side, to keep things balanced. *With an inductance, use
two inductors that are half as large as the single one. *The idea is
the two caps in series or the two inductors in series make the
specified net capacitance or inductance. *With shunt elements, there's
no need to do that, just don't ground either side---the shunt elements
go across the balanced network from one side to the other.

Cheers,
Tom

Hi Tom, Thanks, I just wanted to confirm what appeared to be
happening.

Gary N4AST