Testing some home made antennas
I started my first month of hamradio activity being busy with some homebrewed antennas, here at home. Typical for several hams, no way to install any antennas on the roof, at the moment. Waiting for a new location, I appreciate so much my 20-meters-off-the-ground balcony! 
My first experiment was to build a buddipole-like antenna and I actually have built a prototype, using aluminum and PVC pipes, according to some schematics available on the internet. I've used 16 mm diameter PVC pipe for the inner radials, supporting copper wires and tuning coils. Outer radials were made by 6 mm diameter aluminum pipes, about 150 cm long each.
As expected, searching for a good tuning point has been very difficult and required long time. Also, the fixed length of radials was another relevant constraint. I only tried on 40m and 20m bands and I could find a good configuration on 40m, but a narrow acceptable bandwith (less than 100 kHz). On the other hand I planned the mechanical structure to be able to by-pass inner radial, for a possible use on 6m band, and in this band SWR is good (about 1.2:1 in the lower part of the spectrum). The 6m configuration is stable and light.
What I've learnt: if you want a light and effective antenna for field operation, buy yourself a true Buddipole and spend a little time to find your optimal settings. Or ask some good trees to support your half wave dipole.
However, I planned another vertical short antenna for 20m and 17m band in order to reuse one aluminum radial and a magnetic base (16 cm diameter) with SO-239 connector. The idea was to mount the vertical antenna on the balcony rail. The vertical available space was about 200 cm. So I've built a short PVC support for the aluminum radial (about 40 cm long), including a PL-259 connector, a 20 cm long coil and a 20 cm long copper wire. In this case, finding a good configuration has been easier than the previous attempt. Moreover, I get a good 1.3:1 - 1.5:1 SWR. Not only: the 17m configuration works great on 15m too!
Another test I've made was to try my old 8.5 m long fishing rod antenna and 4:1 un-un that I used last year during my 11m band activity. Of course, I cannot install this antenna on my balcony, so I've been testing it on the field. I've a good response on 40m, 17m, 15m, 12m and 10m bands, getting SWR from 1.2:1 to 1.6:1 (depending on the band). RX is very good too, not very noisy (I clearly receive stations from USA and Japan when conditions are good).
My last antenna for HF (at the moment) is the old boomerang I used for 11m band activity. I've shortened it in order to get a good SWR in the lower part of 10m band.
Another antenna I've built is a J-pole for 2m band using 6 mm diameter aluminum pipe. Very good antenna, it works fine.
Waiting for a VHF/UHF dual band antenna, I also have built a ground plane for 70cm band, using an SO-239 connector as a support and some 17 cm long 2 mm diameter copper wire. Once more, good RX and TX: I can activate some repeaters (distance is about 100 km and more) using a couple of watts only!
For more photos about my hamradio activity, please check my Radio set on Picasa Web Albums.
