city to use a separate receiving antenna may be only one variant
to be on the Air. Interferences from nearest electronics devices
could force it. Below here it is described receiving antenna from
far 70-s that may solve the hard modern situation.
works at 80-, 40-, 20-, 15- and 10- meter Bands. Antenna receives
mostly radio waves having horizontal polarisation. Industrial
electrical interferences as usual has vertical polarisation. Commercial
and ham radio- stations as rule have antennas with vertical polarisation.
So, the antenna allows decrease at receiving input both as interferences
and signals from nearest radio- stations. At right installation
the antenna reduces unwanted signals with vertical polarization
up to 20- 30- dB. However the antenna would effectively work
for receiving DX station because the stations have as vertical
as horizontal components.
circle diagram directivity in horizontal plane and 8- shape diagram
directivity in vertical plane. It is horizontal loop antenna that
feed by transmission line in standing wave mode.
1 shows design of the antenna. Loop antenna made
from two length of the same coaxial cable (item P/2). Feeder L
made from the same coaxial cable as loop of the antenna. It is
possible use any coaxial cable- 50 or 75- Ohm.
Front Cover Radio # 12, 1977
electrical length lambda/2 at 80- meter Band, lambda at 40- meter
Band, two lambda at 20- meter Band, three lambda at 15- meter
band and four lambda at 10- meter Band. Receiving part of the
antenna is only loop. When the loop made symmetrically relative
to the axis AB the part L cannot participate in receiving. Antenna
has input impedance in several Ohms. The antenna may be matched
with receiver by some known methods. Antenna has efficiency in
several percent at 80- meter Band to several tens at 10- meter
It is possible
to increase the efficiency of the antenna at low bands by increasing
of the diameter of the antenna loop.
Title of the Article
the antenna lost circular diagram directivity at P more the 0.35