antennas related projects and information.
at 3.5 MHz
We have a horizontal loop of 4 wires of 20m each at 15m
This antenna will resonate normally at 3.82 MHz using F MHz = 306
/ Lenght of loop in m.
The project looks like this:
CM Horizontal loop
CM also known as "Sky warmer"
CM very good for local at low heights
Over Ground 13 5 (Diel. - Cond. mS)
GW 0 10 0.000 0.000 0.000 0.000 20.000 0.000 0.002
GW 1 10 0.000 20.000 0.000 20.000 20.000 0.000 0.002
GW 2 10 20.000 20.000 0.000 20.000 0.000 0.000 0.002
GW 3 10 20.000 0.000 0.000 0.000 0.000 0.000 0.002
S 1 5 100 0
How do we plot gain patterns?
- Open the Far Field pattern window using Plot
- We click first on ZEN
to plot the Zenith or elevation pattern
Angle should be 0 which means we are plotting an elevation
pattern in the direction of the 0 deg. Azimuth (horizontal)
- We get a pattern with some lobes. The angles
for the lobes are printed on the left side of the plot. By
clicking on Angle with the LEFT mouse button we will load the
best elevation angle in Angle. This means that any
horizontal pattern we plot will be at this elevation.
- Click with left mouse button on Angle
- Click on Az to plot the horizontal
pattern at the elevation displayed in Angle.
- Click on Angle with the RIGHT mouse to load
best Azimuth if not zero.
- A click on Zen will now plot the BEST gain in
horizontal and vertical.
Gain and Patterns for this loop
At 3.5MHz the gain is 7.85 dBi at 90
degrees which explains the "could warmer denomination". No
need to plot horizontal pattern at 90 degrees.
At 7 MHz we have two lobes of 5.6dBi at 39 deg
elevation. Note how horizontal pattern has four lobes at 90
At 14MHz we have now three lobes but two are 7.05
dBi at 20 deg. The horizontal pattern plotted at an elevation
of 20 degrees show multiple lobes in horizontal plane.
At 28 MHz we get a lot of lobes because we are too high
from the ground
At 10 degrees elevation we have a butterfly pattern with
max lobes at 23 deg azimuth (and 156, 204, 337 deg)
If we click with right mouse on angle to load 336 then
plot a ZEN pattern we get the vertical pattern in the direction of
the 337/154 lobes. We see that the lowest lobe is 11.17 dBi at 10
We can try to left click and plot a horizontal pattern
at the 10 degrees elevation but will just get the pattern above
which means that we found the maximum gain for that band.
If you have questions, comments, critics, suggestions: