Doing some fall antenna work ahead of the winter weather. After testing the 6/10/15 fans one at the top of the hill and one just up behind the house become quite apparent to me just how much better the antenna performs at the top of the hill , 1 to 2 S units .... huge! I currently have 6 IFL runs to the top of the hill. The original has been there 20 years and no longer test good. There is 2 connection in the 500' IFL so I am going to isolate which section is bad. There is one IFL that goes from the 4X1 switch that ends about 100' from the top of the hill. Its has been protected from the weather and is probably good for future use. There are 2 in use that test well , the 160m inverted L and the 15/10/6 Fan. The other 3 terminate at the old 80m Vertical ( not in use IFL bad), then one IFL that ends to the left of the old 80m then another that terminates where the 6/10/15 is located. I have a 80/40/20 fan just up behind the house that I would like to recreate at the top of the hill. It will be really interesting to see if I get the same sort of improvement with it there. Depending on when the weather closes in am going to first get 1 or two of the existing IFLs to the top. They are all put together in chunks so its just a matter of isolating the bad bits. If I don't get there this fall then it will be next years project.
Thursday, September 22, 2022
Friday, August 26, 2022
Fan vs Fan
Built another 6/10/15 fan more or less the same as the one at th etop of the hil. New fan is just up behind the house about 35' above the ground and somewhere around 50' lower in overall elevation compared to the one at the top of the hill. I had both antenna on the same 4 X 1 switch. All of my signal reports on both antennas seemed to always come up about 10 db less then what I was reporting. Propagation has a a lot to do with it however I was suspicious of the IFL run between the house and the switch 100+' of a good diameter hardline.
First thing I did was to move the new antenna to my other 4X1 switch but it didn't seem too make any difference still was getting on the magnitude of -10 db over the reports I was handing out. I terminated the IFL to the "hill" switch with a 50 ohm load and swept the IFL with the Nano. I had a "spare " line of the same IFL and swept it too and compared both .
IFL feeding the "hill" 4X1 switch
Spare IFL
So ya , both IFLs are good...phew. Going from the house to the hill the IFL is burried , about 30' and its a pin to replace it.
This morning I flipped between the new fan and the old one on top of the hill over a 1 hour period. 15m propagation came into play from time to time but flipping back and forth keeping the transmission numbers about the same should take propagation out of the equation.
Existing 15/10/6 Fan on the top of the hill. VA3IMI
New fan just up behind the house . VE3LDP
I was really expecting the new 6/10/15 to outperform the old one just simply because the IFL was so much shorter but that isn't what happened. The antenna on top of the hill has a 360 degree clear LOS vs the one behind the house that has LOS blockage from about 350 deg through 120 deg.
So the new antenna is coming down and I am going to beef up the antenna on the hill and do a once over on the IFL to ensure its protected against the weather.
Saturday, August 6, 2022
Thursday, August 4, 2022
15/10/6 Fans Testing ...Round 2
Waited until early eve then repeated the same test as this morning CQing every other minute each antenna for 30 minutes. Once again the fan on the hill wins. I had Oman and Italy answer my CQ using the old fan on top of the hill.
VA3IMI , fan on top of hill
VE3LDP, new fan.
New 15/10/6 Fan Dipole
Last antenna season I put a 15/10/6/2 Fan Dipole at the top of the hill. I was suspecting some losses in the 500' of mostly LDF4 but it seemed to work well but I seemed to always get signal reports that were 10 db less then what I was reporting..ie IFL loss.
I just cranked out a 15/10/6 Fan Dipole the same build more or less as the one on the top of the hill. I have mounted it about half way up the hill with about a 300'shorter IFL. This new antenna is pretty high at around 30ft maybe a wee bit higher above ground then the top of the hill. As a test I did alternating CQs between the 2 Antennas using my two call signs. I did this alternating between antennas every 90 seconds to 2 minutes over a 30 minute period. Should be enough to take propagation out of the equation.
VE3LDP the new fan is broadside 30 / 210 ( not quite running NNE / SSW ) where IMI the old fan broadside is 0 /180 ( runs east west ) . Not hugely significant!
VE3LDP is the new Fan ( shorter IFL, 200' and lower on the hill )
EU
VA3IMI is the old Fan ( top of hill 500' IFL )
EU
Clearly there is an advantage to the fan at the top of the hill , a bit of a surprise to me I was expecting less loss so better TX not thinking the position on the hill would make that much of a difference.
Swept both fans on 15 m.
VE3LDP is the new Fan ( shorter IFL, 200' and lower on the hill )
VA3IMI is the old Fan ( top of hill 500' IFL )
Return loss is an important number to look at in terms of the efficency of the antenna. The way I thinks about return loss is .
If the return loss is 10 dB, 10% of the power is returned. While different systems have different acceptable return loss limits, 15 dB or better is a common system limit for a cable and antenna system.
Both antennas range from 19 to 28 db return loss the new one is slightly better but the are both very close to each other.
Next up is to sweep both IFLs into load.