ladderline and antenna mast separation distance

[KJ4ZFJ]

I'm putting up a 10 meter yagi on a mast but while doing this, I want to move my G5RV to the mast with a horizontal support to improve access.  How much separation do I need between the G5 and the metal antenna mast, i.e. length of horizontal support to hang G5 from? Thanks! 

[K3MRI]

Hi Tim. I 'think' I can visualize what you mean. The antenna mast may not be your main, or at least only, problem. How high off the ground is the Yagi and how far below the Yagi will be the G5RV. Also, I'm trying to visualize what you mean by a horizontal support.

Thx

73

Jim

[KJ4ZFJ]

The yagi will be about 35' high and the G5 at some point at least about 5' below the yagi. I plan to clamp a length of a fiberglass rod extending out 90 degrees from the mast (parallel with the ground).

[K3MRI]

Got it. So, what you're really interested in is how far horizontally do you have to be from the G5RV and or the redline. Regardless of whether you use 300 or 450 ohm ladder line, you literally only need inches. The common practice is twice the width of the ladder line. So if, hypothetically, the ladder line is 1-inch wide, you need to be two inches away from metal. So as long as the antenna and feedline are a few inches away, you're good to go. Will the tower have a pattern impact? Same answer as the next paragraph.

As far as interference between the Yagi and the G5RV, I have not modeled it but the five foot spacing is ample. Of course, two antennas will always affect each other's pattern, but a wire antenna sitting five feet under a Yagi will have insanely negligible effect.

[KJ4ZFJ]

Thanks for the response on this.  Exactly what I needed!