> Consider the case of a conventional T network matching an
> impedance lower than the lowest obtainable surge impedance of
> the network. With 220pF capacitors, that would be about 3000
> ohms on 160 (1500 ohms on 80 meters, 750 ohms on 40 meters,
> and so on).
Woops, the results are correct but I described the impedance
wrong.
In this case the surge impedance of the network would be the
geometric mean of the input and output impedance. Phase shift
would be 90-degrees, and the network would appear as the
electrical equiv of a transmission line 90 degrees long with an
impedance of the square root of 50*3000, or 387 ohms in the 160
meter example I posted.
In this example, all components are adjusted to have the same
reactance. This is the lowest possible operating Q matching
system between a source and load resistance.
73, Tom W8JI
W8JI@contesting.com
List Sponsored by AN Wireless: AN Wireless handles Rohn tower systems,
Trylon Titan towers, coax, hardline and more. Also check out our self
supporting towers up to 100 feet for under $1500!! http://www.anwireless.com
-----
FAQ on WWW: http://www.contesting.com/FAQ/towertalk
Submissions: towertalk@contesting.com
Administrative requests: towertalk-REQUEST@contesting.com
Problems: owner-towertalk@contesting.com
|