As previously annnounced, enhancement of
the Roomcap Antenna continues.
This
week I tested successfully an interesting new feature:
The
Remote Frequency Adjustment RFA does no longer require a separate
control
line. The control voltage is now sent over the coax by inserting
a rf-dc-
separator,
one on the transmitter side, and one on the antenna side.
The
idea was developed with the magnetic loop antenna, and now adapted to
the
specific
requirements of the Roomcap antenna.
This
week the field test was performed with a 70m long coax line between
transmitter and
antenna.
Insertion
of the two devices produced no detectable attenuation of the system,
with
the advantage that the separate control line could be eliminated;
and very
important: The short distance of the control line to the antenna
created an rf
current on the control line, which had to be filtered.
This
problem is now eliminated, as this line is no longer existent.
The
next update of the construction guide will contain this new enhancement.
Here
are the pictures:
The
black box is the 50 ohm rf/dc separator on the transmitter side (1.8 -
30 MHz)
The white box is the 50 ohm rf/dc separator on the antenna side (1.8 -
30 MHz)