and Undeground Antennas are widely used
at Stationary Radio Communication Bases of Russian military. Some
of such old antennas were described at Reference 1.
article is described another Russian military
Spreading Antennas- BAZA- 500D and BAZA- 1500D.
The antennas are used until recent days. Article is published
with unimportant cutting.
References: I. Grigorov. Antenny. Gorodskie Konstrukcii. M.: RadioSoft, 2003. ISBN: 5-93037- 109-1. In Russian
Insignia of communication troops
Practice shows that after both or nature disasters
(hurricane, snowstorm, etc.) either just a planned turn off of
stationary antennas (repair work or
preventive inspection) it is possible very fast
restore the radio communication using Spreading Antennas (SA).
The antennas can provide communication coverage near and far distances.
Here it is necessary to note here, that design for
SA used for ionosphere radio communication is defined by the necessary
frequencies band and distance.
The longer is the distance the lower should be antenna
lobe. For close distances (up to 500-600 km) use NVI (Near Vertical
Incident) which is radiated at 65- 90°. Interesting, that the
antennas may have low G (gain).
Antennas radiated at 20- 65° are suitable for middle
distances up to 2000 km. Far
distances (more the 2000 km) require antennas radiated at 5- 20°.
However, the more is distance the more gain should be antenna
have to compensate losses at propagation. Receiving SA should
have good directivity and gain (although the requirements for
gain are not so tie as to transmitting SA).
that SA intended for ionosphere communication should be made broadband
(low directivity at 1,5- 12 MHz (i.e. NVI, I. G.),
high directivity at 3- 30 MHz) and the SA should have good match
with feeder and good efficiency (travelling-wave factor must be
lower the 0.3).
SA can provide communication at day and night on any period solar
activity (high and low).
Russian SA BAZA- 500D, BAZA 1500D, BAZA – MD (several phasing BAZA 1500D) meet the above writing
requirements. The SA has been working for years at Soviet Radio
Bases and these ones are very reliable in operation. These SA
are described below. Spreading Antenna BAZA 500D is a low directivity
one. It is NVI antenna for 2- 10 MHz. The antenna described at
Voennyj Vestnik # 9, 1993 (Russian military magazine). Design of
the SA is shown at Figure
BAZA – 500D:
implemented from four in pairs reciprocally orthogonal flat shunt
radiators (so called Square Radiated Vibrator (SRV) item 1. Each SRV has sides equal to
3 meters. SRV made from metal tape having 1 mm thickness and 20
mm wide. SRV connected each other by shunt item
One pair parallel vibrators of the module is fed at
points a- a by lengths of a 75- Ohm coaxial item
3, the lengths connected to main feeder
item 7 (hts
eats in points and - and " with the help of distributive
pieces 3 êàáåëÿ ÐÊ-75, which
incorporate with ôèäåðîì
7 (75- Ohm coaxial ) through a matching
length of 50- Ohm coaxial, item
5. Other pair SRV is feed at point b- b
with help items
4, 6, 8 (similar to 3, 5, 7).