Hi Steve

Many years ago I use to do early morning exercise walks in the mountain
range immediately to the west of Sydney's metro area. As soon as I
dropped off the western mountain edge all rptr sigs were still audible
on my IC2A but they couldnt hear me.

I made up a 2M jpole out of 10mm aluminium and tied it to my backpack
with rope and/or rubber straps. The thing wobbled a bit but stayed more
or less vertical. The backpack was very floppy, a more rigid one would
have been better. There was about a 1/2 metre metal extension from the
base of the matching section to faciltate the rope binding. The thing
was about 1.3 metres max height above my head.

I also built a 10W PA running off 12 D cell NiCd's. Worked very well
until the constant battery pack flexing shorted something and the hot
wiring melted a hole through the backpack pocket it was sitting in!

If the extra matching section length is an issue you might find other
ways of end/voltage feeding the 1/2 wave. Lots of possibilities here.
You could also use a fibreglass rod with 300 ohm ribbon tied to it in a
jpole or slim jim form. Handy in a region of low flying trees.

Height on LOS frequencies is everything . Getting the antenna above your
head will make a huge difference. Everyone thinks you are a
extraterrestrial visitor too!

Your present mobile antenna will need a counterpoise. (aka groundplane)
I suggest you discard the idea of using it unless you can get use to the
trailing 1/4 wave wire(s). Maybe it would work by mounting the antenna
on an extension so its base is about head height, then wrapping three
ground radials down the sides of the backpack. You could make it more
permanent by weaving the wire into the backpack itself.

Cheers Bob VK2YQA (in W5)

Steve - www.ukspeedtraps.co.uk wrote:
Hi All

I want to construct a backpack antenna that can be left on my rucksack and
used when walking.