ARRL

0006005968H80

 Joined: Sat, Apr 4th 1998, 00:00 Roles: N/A Moderates: N/A

Latest Topics

Topic Created Posts Views Last Activity
Calculating Impedance Dec 9th 2013, 23:56 7 6,786 on 11/12/13

Latest Posts

Topic Author Posted On
Calculating Impedance 0006005968H80 on 11/12/13
This is what creates the uncertainty. It would be worthwhile to eliminate the forbidden lengths, but the side effects might create worse problems than are solved. I hoped there was a formula, graph or table that might give some insight.

Unfortunately, although I have EZNEC by virtue of having the 22d Edition of Antenna Book, I do not have enough familiarity to use it..... one of the projects on my list once I get this antenna up and on the air.
Calculating Impedance 0006005968H80 on 11/12/13
In the process of putting up a ~31' vertical over 36 radials, and in the process of understanding the remote tuner situation, I think I would like to be able to know what the matching impedances the tuner is going to face on different bands.

I have the AH-4 auto tuner which reputedly has a range of ~4 to ~5000 ohms. Is this enough? Icom says to avoid half wave wires, but DX Engineering sells a magic box that likely is a transformer to reduce the impedance to within an acceptable range.

If you have this ~31' wire, it seems to me it has one impedance at 7.1 Mhz, another at 14.2 or so, yet another at 21.3 etc. Is there a formula or table to ascertain what it is likely to be?
Calculating Impedance 0006005968H80 on 9/12/13
Is there a formula for calculating the expected impedance of a wire of a given length at a given frequency?

Example: with a 45' wire at 7.1 Mhz one would expect the impedance to be matched of what?