Last Revision: 26 May 2008
On 17 May 2008 Ulli, DL3YEL, came visiting me and brought the long awaited 6 element for 50 MHz. What a big antenna ... The day before I had taken down the tower, mounted the vertical rotator and the 2x9 element antennas for 70cm I had built in April. I had rewired everything and we only had to mount the antenna. Unfortunately it began raining, the only rain within weeks. We got the antenna tuned to 50,1 MHz and finally raised the tower again. All antennas have a very good match and work as expected now.
A view of the DF9CY Antennas for 40m, 6m, 2m and 70cm
The antennas are mounted in a way that the capture area of the single antenna is disturbed as little as possible. The capture area is about half of the stacking distance of each antenna. For the 6m antenna this would mean about 2m to either side of the antenna. For the 2m antenna this would be about 1,5m and for the 70 cm antenna I suppose the capture area is about 70cm to either direction. Best of all seems to be the 2m antenna. No big structure is close to the antenna. The 6m antenna will suffer from some influence from the tower. There is still the 40m dipole, which is resonant on 49 MHz on the 7th harmonic and is close to the 6m antenna too. I can well see influence of the 40m antenna to the 6m beam. I will remove it for the time of the 6m Sporadic-E season.
Another view of the antenna
The 50 MHz antenna is a big improvement over the older 4 element I have used for 3 years. In my eyes it performs extremely well. I wound up the spare coaxial cable (low-loss H2000) to form a choke. No more influencing the automatic light switches (this happened even at low power levels) and the 6m has become very calm concerning birdies. The 40m antenna below is doing better than before because it has about 3m more space to the walls of the building.
The 144 MHz antenna can be elevated for moonbounce or satellite work. The 2m antenna on top works as I had it before, eventually a bit better, because it is ca 1m higher than before. Even though the reflector element is close to the 6m antenna at over 60° elevation, I do not see an influence to the SWR of the 2m antenna. EZNEC indicates a peformance loss of about 0,1dB.
The new homemade antennas for 432 MHz. A preamplifier is mounted at the power divider. This 70cm antenna is doing very well and performs as expected from the antenna diagrams.