2 Operating Positions For Testing
....... "Typical Portable Site"...... and ...... "Worst Case Site" .......
POSITION #1: Typical Portable Site:
- Home Owner Association rule and regulations make it impractical or even impossible for many OM and YL to even get on the air from home.
- Many hams live in appatment buildings with no possibility of installing an outdoor antenna.
- The table is positioned directly next to the pole.
- The ground stake is right beside the pole.
- The coax is run straight down the pole which keeps it equal distance from the two legs of a symmetrical dipole.
- This is only 100% symmetrical when nothing is influencing eather side of the dipole more than the other side (e.g., a garage, a parked car, another antenna, etc.).
The length of the coax depends on the height of the antenna's feedpoint on the pole.
For my tests I used 11m for the dipoles and 12m for the OCFD antennas.
In theory the extra meter of coax will skew the measured results slightly, but in practice, assuming CMC is much worse on the fundamental frequency than on the harmonic frequencies, 1m of coax on 40m will not make a significant difference.
POSITION #2: Worst Case Operating Position
I can't find the pictures I took.
This position was located just inside of the door to the house, about 5m away from and 6m underneath of the end of the OCFD antenna.