The antenna
is experimental variant of small directional antenna. Antenna
is easy to do and for tuning, require a small room for installation,
therefore provide good directivity.
Antenna
is made from two aluminum Hula- Hoops. The sport circles
are light to weight, easy to find and there are not expensive.
As usual Hula- Hoop has diameter near one meter (here are used
such Hula- Hoops). Figure 1 shows design of the antenna.
Hula-
Hoop is cut at the jointing, one side of the circle is feed-point
0f the antenna to another side of the circle an aluminum stripe
with dimensions 200 x 25- mm is connected.
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Antenna
is fed through a transformer 50/200 Ohm. Design of the transformer
is shown on the Figure 1.
Antenna
was installed on the wooden mast in 7.5- meter high. In practice
the antenna shows plus 7.5- dB in bidirectional side and minus
26- dB forward- back ratio. Antenna should feed through coaxial
cable with length that does not multiple to 0.625 lambda because
that length may transform antenna impedance to unappreciative
way. Antenna is tuned to minimum SWR by bending the aluminum stripe
inside the Hula- Hoop.
73! de RX3AX
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