On Fri, 31 Dec 2004 18:41:48 -0500, wrote:

I'm basically a lurker in the newsgroup but I've forgotten what the
term as used with an antenna impedance like 30 +J200 or 25 -J150 etc
means. I remember studying it about 10 years ago when I took my extra
test and I had it in tech school at about the same time from a Jr.
College during one 4 credit hour "communications" course that covered
everything from TV's to SSB and FM. I believe it's one way of
expressing an impedance with some reactance thrown in and I recall
converting between polar and rectangular methods of expressing the
same term ( I would really need the book for that now ! ) But I don't
think I have the books from the school days around anymore. Any one
care to give me a short refresher course or post a URL ? I've got a
bad case of CRS ( Can't Remeber Stuff ;-) )

Happy New Year !


Dear Sir,

Try the program "Vectors" at either of the following Web sites. By
plugging a few examples into the program, you will again understand
complex arithmetic.
http://zaffora.f2o.org/W9DMK/W9dmk.html
http://www.qsl.net/w9dmk/

The program does not run under an NT based system, such as Windows XP
or Windows 2000 but it will run fine in DOS under Windows 9x or
Windows ME.

Here is the short tutorial on complex arithmetic:

a1 + jb1 + a2 + jb2 = (a1 + a2) + j(b1 + b2)
The rule for subtraction follows the obvious complement to the above
example of addition.

In order to do complex multiplication and division it is easier to
convert first to polar form, as follows:

Magnitude of a + jb is sqrt(a^2 + b^2) and the Angle is arctan(b/a)

In Polar form the product of two vectors is the product of their
magnitues and the angle on the product is the arithmetic sum of the
two angles.

In Polar form the quotient of two vectors is the quotient of their
magnitudes with an angle that is the difference between the
numerator's angle and divisor's angle.

Example: 5@35 * 6@40 = 30@75

5@35 / 6@40 = 0.8333@-40
where @ means "at an angle of"


Bob, W9DMK, Dahlgren, VA
http://www.qsl.net/w9dmk