Mar 11, 2011

ANY antenna beats NO antenna

Stop modeling and get on the air; NOW.
After having moved, a couple of years ago, I wanted to launch my 160m activities at this new QTH. But the list of opportunities was quickly overtaken by the local challenges. The few attempts were marred either by public exposure (neighbors included), safety issues (see nov 1 2009)and lack of real estate. Next, work and other activities shifted priorities such that I kept stuck at the stage of computer aided antenna modeling.
I had to lower my ambitions as advancing plans to the next season again and again, did not get me anywhere and certainly not the pleasure of simply making QSO's on Topband.

The stealth Topband Antenna
An unobtrusive wire up in the air as high as possible, plus a few radials on the ground resembling some sort of basic Groundplane Antenna are my major goals.
I already tried getting different wires up a large tree, but the launching velocity power of my legal sling shot wasn't sufficient.
A friend offered help by supplying a special tinned copper wire having teflon isolation. At only 0.2mm diameter this stuff is both unobtrusive and extremely light.
With help of the slingshot it is quickly launched in a large tree using a 40g weight at the end.

It's the white wire, routed along branches of a small dead tree in the back garden. The horizontal wire is a short wideband horizontal antenna.
From here it goes upwards to a large tree some 15m away, ending at a height of >22m and then some length horizontal tangled up in the branches. In total I guess, about 26mtrs. Unimportant really, since there are plenty of opportunities to match it on 160m.

A copper ground rod and some 6 attached radials varying from 6 to 9mtr (20-30ft) in length are covering the west-to-northwest quadrant. Minor detail; since the vertical wire rises up in the southeast direction, none of these few radials cover the area under this sloped GP.
The white box is a True Balance type
remote controlled ATU, which was not used for 7 years already. Together with some common mode supressor #31 FT240 ferrite core and already available coax from earlier experiments, I'm connected.

The final picture already shows the current situation where I have added another 10 radials in this small quadrant. The Yagi is my next priority for the summers Es season on 6m. And yes, that door in the upper right does need some maintenance attention.

So how does it play, QSO-wise?
Let's summarize this: a lossy 0.2mm dia wire, an even less-than-poor man's RF ground, a quick&dirty matching unit and 100W input power for that 'Sloped 160m GP'. Good points: it's at least 1/8 wave up and free in the air.
Within the hour I work stations on Topband within a 2000 km range including an UA2, but some later an Asian UA9.
The next morning at 05:54 UTC I work Dave, W5UN. Wow! Was that perhaps a special moment of extraordinary propagation? Later that evening I meet and work another well known Magic Band operator UK9AA. Two more US stations from PA and TX are worked in the next few days. It's no magic, using only 100W this antenna exceeds my expectations.
In between I have added some 10 more radials in by tiny 8x7m backyard. It requires a different setting on the remote ATU.
Using my short RX vertical I can hear many of the active dx'ers and dx-peditions on 160m. Most have large pile ups and are gone before I can make the contact. That is fully acceptable; this must not be too easy right?
New continents are entered in my log soon; JA7NI and today FM5CD. Both take some time before they are able to dig out my puny Little Pistol signal. Slow speed and perseverance while riding the QSB waves proves successfully.
Now how cool is this ???

What's next?
In the next weeks I will try to arrange:
  • Replace the ATU for a Low loss matching unit using a Heavy Duty Coil
  • Detune the TX antenna to lower (induced noise) coupling to my RX antennas
  • Add a PTT controlled RX antenna sequencing
  • Make more QSO's, have fun operating Topband


Mark, PA5MW said...

My CQ-DX has been picked up by RBN's as well:

SM6FMB PA5MW 1814.4 CQ 3 dB 20 wpm 0546z 09 Mar

G0KTN PA5MW 1814.4 CQ 35 dB 20 wpm
0545z 09 Mar

W3LPL PA5MW 1814.4 CQ 17 dB 20 wpm 0545z 09 Mar

K3MM PA5MW 1814.4 CQ 11 dB 20 wpm
0545z 09 Mar

73 Mark, PA5MW

Claudia said...

Congrats on your new and cool QSO's - sometimes a "puny pistol" is all you need :D
But ehh, what some colour [+ plants] in the garden - to compensate the dead tree and broken pottery? :):)