OH2FFY                    

08/05/08

Stationary Mobile Antenna for 20


This is the story and build log of this antenna project.






One winters day I was out with my field day setup , a 100W Yaesu feeding into a ground mounted 1/4 wave vertical.
This usually works quite well despite its simplicity.

Now I hear another local ham about 20kms away calling CQ - It was Niko OH2LZC.
We chatted for a while and he told me that he was running a fully mobile station with a multiband helical whip of only 1.75 Meters in length on his Ford Ka.




Niko's antenna is small , and I considered it to be a bit of a joke, but I was about to be 'learned a serious lesson'.



We heard a VK3 station , that was quite strong having many good contacts with Europe.
I was listening to the replies and most were from countries a bit south of my location , so the DX path wasn't ideal for us here in Finland.

With my superior and bigger antenna I was located in a car park of a sporting complex near my house about 10km from the ocean on the southern side of Finland.
My ground was not the best , my horizon was a couple of hundred meters away as I was in a dip surrounded by buildings and trees
, but I did get some good contacts during the day , so I felt that I had a good chance of catching this VK3 contact.

Now Niko was in his Ka about 25km away from me , but he was located exactly at the sea shore where he had a conductive ground with a long horizon view to the the south toward VK land.

So Niko was putting out calls , and I was calling too.

The sad end of the story is that Niko got the contact and I didn't. :-(

http://www.youtube.com/watch?v=mfR4h8v3PFs



*** You cant judge a DX'er by the size of his stick ***



Yes , even with his inefficient helical stick antenna he still got a good contact BECAUSE of his location.

Here in Helsinki city there are pretty well no public open spaces suitable for setting up an antenna like what I use and operating at home is likewise impossible for me due to highly restrictive tenant regulations.

A portable station is my only choice , and while I don't mind braving the minus 15 degrees in winter in order to DX , it is not too good when your setup isn't as good as it could be.

What the Niko experience taught me is that a good location is worth more DX miles than the efficiency of your antenna.


I don't intend to retire the full size 1/4 wave vertical just yet , on good soils near the ocean that things screams out well , so my plan is to make a car mounted antenna that I can more easily take with me and use in more suitable TX sites.

One option is just buying a short stick like Niko's , but the fact remains , that short helical whips are poor radiators.


This article will detail the build of a vertical for stationary mobile use that will not compromise efficiency.
.