12
Topographical Considerations
Flat or gradually sloped land is best. Erecting the transmitting array on steeply sloped land or
uneven terrain might degrade performance. To avoid pattern degradation, antenna elements should
have reasonably similar elevations. It's recommended the maximum ground height difference
between any of the vertical antennas in the array should be less than 20% of the array diameter. For
example, a 64 foot square array should be within 12 feet of level. Every effort should be taken to
make the elements symmetrical. Elements should be very similar or identical in construction and
grounding. Elements should be mounted above any standing water or snow line, but as close to the
ground as possible. In general, the system will not be affected by trees or foliage so long as the
foliage is not near an element. The open ends or tips of the elements are particularly sensitive to
close branches or foliage. There should be a reasonably clear electrical path for at least 1
wavelength in important receiving directions. The site should allow a radial system to be as evenly
distributed around each of the vertical elements as possible, although perfect symmetry isn’t
important so long as the radial connections are good.
Most amateur radio operators in North America will want the
system to point toward Europe as a default (position 1). Therefore
the system will be laid out with vertical antenna elements 1 and 2
along with vertical antenna elements 3 and 4 pointing North.
Note: This array, like all four-squares, has a fairly wide flat forward
lobe. This means exact direction headings are generally not critical.
We should still remember there is a difference between True North
and Magnetic or Compass North. Without going into all of the
details, you want your system aligned to True North. Depending on
your location you can check your position using various geological,
topographical or aviation maps to determine True North.
If your location has more than 10 degrees magnetic declination, you may want to correct for it.
Declinations below ten degrees can be safely ignored.
If you know your longitude and latitude, you can then pinpoint yourself on an aircraft navigation or
geological map. If you don't know your longitude and latitude, you can find that information on
many of the map services available on the internet, or use a GPS.
Site Selection in Relation to Noise Sources
Since the array is generally used for both transmitting and receiving, you should listen to desired
bands and identify any sources of unwanted noise. Elimination of noise sources is required for
optimal receiving results. If noise sources cannot be eliminated, then locate the antenna array as far
away from noise sources as possible.
Since this array is directional diagonally across its corners, locate the array so the rear of the array is
pointing towards the dominant noise source. This ensures the array has maximum suppression of
noise when beaming in the primary listening direction. For example, if you primarily want to work