Tests are taken from my roof top in Burbank,
When I conduct tests, they are done very quickly. I have a receiving
receptacle above my rotator that allows me to switch antennas with no tools.
This is very important as reception/weather conditions can change quickly.
Local stations are picked up from Mount
Wilson, about 15 miles away at a
3200'-3600' elevation. Attempting to pickup stations from Mt. Wilson can be a good test for multi-path
interference from this location.
About 5 miles away is a large mountain peak that rises about 1000' above my line
of sight with the transmitters. Signals must travel either over or around this peak.
My receiver must differentiate between the good signals and the bad. The
direction of my antenna indicates that strongest
signals are traveling directly over the peak. The signal either bends over the mountain (knife
edge effect) or reflects off the atmosphere to reach
my antenna. For this condition, a medium gain antenna with good multi-path rejection
(high F/B ratio) performs best.
Long distance stations are picked up from San Diego, about 130 miles away at
a 700'-1800' elevation. There are no significant mountain peaks in my
line of sight. Due to the distance, the line of sight is actually being blocked
by the curvature of the earth. San Diego is a coastal town, most of the path
the signal travels is along the coastline. Because of this, weather becomes a
critical factor in signal reception. In favorable weather conditions, signal
levels can be very high with the help of tropospheric
ducting. In bad weather conditions, the moisture and fog in
the air can create a "wall of water". The lack of the
"ducting" causes the signal to completely disappear. A high gain antenna is
required to pick up these distant stations, but you will still need favorable weather
conditions to get reliable reception.
|Set Top Box -Tuner
||RG-11, 50' antenna to receiver
|Antenna Height above ground
||30' = 17' house + 13' mast
||1.375" diameter, telescopic 30-48", 3"
||(2) 1.250" diameter x 4-1/2' length, tempered steel, interlocking