Introduction: I desperately need in rx/tx antenna that could be work at HF- UHF bands without any
tuning. The antenna should be work at any conditional and should
be simple in design. Below you find description of my design of
Lavrushov , UA6HJQ
From some time I used to an FT857D. This transceiver
has not an internal ATU, so, I have to use only matched antenna
with this rig. At first I tried a length of a wire in 14- meter
going from a window of my balcony to the ground at angle of 50
degree. This wire was matched well at all HF- Bands and allowed
me did operation in the Air.
soon I understood that the antenna had some disadvantages.
when band has changed I have to go to the next with the balcony
room to tune up the antenna, secondly, the antenna was too noisy. Figure
1 shows the antenna.
I decided to design antenna that do not require any tuning and
that has no so much noise. It would be possible if the resonance
antenna was converted to aperiodic antenna like a T2FD. However
I have no place for original T2FD, and I already have installed
the 14- meters length of wire, that is why conversation to be
applied only to the wire. Figure 2 shows schematic of the
antenna. Resistor for 50- Ohm is old surplus dummy load. Counterpoise
is a 5- meters length of wire that is placed around perimeter
of my balcony. Coaxial cable 50- Ohm from the antenna to FT857D
has the 7- meter length.
Figure 2 Aperiodic
antenna for FT857D