John,
Very impressive looking antenna. One question...
Why did you connect the 4-conductor cable wires in parallel? I assume
to resonate the loop.
I am thinking of something similar but series connected and untuned.
73,
'Bear' NH7SR
--- In loopantennas@..., "John Nelson"
<jnelson123_us@y...> wrote:
I just posted a picture of my long wave and middle wave loop in the
pictures section. The actual antenna was made entirely of salvaged
materials for the exception of the brass bolts and nuts in the
center
section. The outer loop is made of 4 wire flat telephone cable
with
all sections paralleled. This section is a spiral loop on just one
side of the support sections. The next section is the MW loop and
is
made of 14 ga. conduit wire and is wound in a basket fashion so as
to
hold down capacitance. The coupling loop is on the inside and is
two
turns of two conductors in parallel. I thought originally that I
could use the same loop for both bands using taps but the
capacitance
of the wire made tuing up high enough for MW impossible. Using
Varicap diodes in series it is possible to tune _nearly_ all the
bands but not all. I finally put in a switch to switch one pair of
diodes in and out and can easily cover more than half of each band
with the high or low setting. The metal box contains a FET
preamplifier, in/out switches, and the voltage for the diodes. It
certainly is easier to tune the diodes remotely than to bend over
and
adjust a variable cap. BTW the support section is not near strong
enough-that wire in the LW section is really heavy. On the 175-525
KHZ band, I have yet to detect anything but non-directional beacons
but I'm still looking.
