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.
The antenna 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.
Antenna has 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