Well, why I did a Two- Elements YAGI? Why not Three,
Four or more Elements YAGI? Or, say, so popular 2-5/8 or 3-5/8
Vertical Collinear Antenna?
Okey, at first, just begin from the beginning. From
the theory. As the theory says, multi elements antennas (in the
case, YAGI) have a large near field zone. The more elements the
antenna contains- the more sized near field zone the antenna has.
All subjects that are located inside the near field zone are influenced
to the parameters of the antenna.
Conclusion: So- the more elements an antenna is contained - the more free space should be around the antenna.
was proved by me. For a while I had to use a commercial (from
www.tangenta.ru) made Four and Six Elements
YAGI. The antennas are perfect antennas only the antennas have
enough large free
around, for example, the antennas are installed on the roof. But
I need a balcony antenna. Place at balcony was very limited. I
could install only antenna that goes at 1- 1.5- meters outside
the balcony. Only the limitation makes me to look for an antenna
suitable for such conditions.
Four Elements YAGI works bad at such
close to wall (up to 1-meter) installation. There was so called
"ladder" effect. The effect means that at one frequency
a station is going at 59, step to 25- kHz the station is going
at 58, another step 25-kHz- 59. The more elements have YAGI- the
more the "ladder" effect presents. Where a Two Elements
YAGI is working at 1 meter from a wall there Four Elements YAGI
is required 1.5-meter distance from the wall.
is- why not collinear but YAGI. Collinear works badly at my installation
on the balcony. Lots reflected and spurious signals from nearest
buildings do the reception too noise and unpredictable.