ARLA/CLUSTER: Episódio 143 da série "Foundations of Amateur Radio"

[João Costa > CT1FBF]

 Foundations of Amateur Radio #143

*What improbable antenna solution works?*

There is some truth in simplicity. I've mentioned in the past that "suck it
and see" is a perfectly valid solution to figuring out if something is
going to work or not.

I've moved into my new home, my new QTH. The roof is colour bond, that's
basically a corrugated iron roof, painted in some random colour. I think
it's grey, but don't quote me on that, could be green.

Inside is a mezzanine floor, essentially carving out a space within the
roof area. It's going to be my office and radio shack, so after setting up
technology, I had a spare 15 minutes and came across a box that had my
radio bits inside it. After setting up power I went and combed through some
more crates to locate a magnetic mount and the vertical I use on 2m and
70cm in my car.

The roof beam is held up by a steel post which forms part of the railing
that surrounds the mezzanine floor.

All conventional wisdom tells me that this is a poor place for an antenna.

So, undeterred with little else in the way of simple options, I stuck my
magnetic mount to the steel post with my vertical attached. Of course this
doesn't mean that I have my vertical actually mounted vertically, in fact
it's not, it's horizontal.

So, there's one of two steel posts that holds up the steel roof, a magnetic
mount stuck to the side of the post with a vertical, running horizontally.

It keyed up the local repeater the first time. Made some contacts, spoke to
three local amateurs to confirm that they could in fact hear me, swapped
sides on the post, from parallel to the roof line to 90 degrees off the
side with some improvement.

Now as I said, on paper this shouldn't work. The roof beam runs
north-south, the repeater is off to the east of the pitched roof, so the
signal isn't making its way off the ends, it's going through the roof, or
I've managed to use the roof post as an antenna, or the roof, or both, or
the signal is bouncing down, over a metal fence, who knows.

The point is, it works when anyone you'd have asked about this would have
rightly told you that it won't.

When I asked recently what the ideal shack should look like, one person who
travelled a lot pointed out that just enough shack is a good place to
start. Right now, I'm a power supply, radio and a horizontally mounted
vertical into the minimal shack.

I was asked if I'd tested HF yet. Seriously, the radio is 15 minutes out of
the box. But in a word, yes. I put on a 10m vertical, also mounted
horizontally, same magnetic mount and I can hear the local beacon on 10m,
12m and 15m, a vast improvement on my previous HF experiences at home.
Overall the noise on the bands seems less than it was in my old house -
this could be because of shielding of the roof, or it could just be less
actual noise, or because my antenna is mounted horizontally. Previously I
had S9 noise, now it peaks at S5, but on average it's around S2-3. This is
not a proper test by any stretch of my imagination and while initial
indicators are better, this is by no means a definitive test of the HF band.

For my next trick I'll be taking a closer look at the railing that
surrounds my office, It's made from stainless steel stranded wire, the
stuff you find on a boat, with seven strands to choose from, in three
separate orientations, so plenty of room for experimentation and more if I
dare to use the strands on the staircase, seriously, I won't be.

One thing I will do before I start keying up for the next HF contact is do
some electro magnetic radiation research to learn if I'm in the danger
zone, or if my family might be exposed to unsafe levels of RF radiation.
Normally this isn't an issue with 5 watts when the antenna is on a roof,
but now I have it indoors I'll spend some time making sure.

I still have a magnetic loop on loan from a friend, packed away in a box
that I'll unearth in the next couple of days to see what it has to say
about the new RF environment.

As I said this is just the beginning and I've not yet been calling CQ or
checking out the local HF nets.

What crazy set-ups do you admit to, that actually worked, even though they
shouldn't have?

I'm *Onno VK6FLAB*



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