Aerospace and Electronic Systems Magazine June 2017 - 54

Early History of Polish Radars
The built-in IFF equipment was the
well-known Soviet made KREMNI-2, which served afterwards,
practically unchanged, in several
generations of radars used in the
Warsaw Treaty countries until the
early 1990s when the Treaty collapsed.

BOGOTA HEIGHT FINDER
The BOGOTA was developed at
the RAWAR factory, with its acceptance trials being accomplished
in 1963. It was actually an upgrade
of the NYSA-B; the replacement
of the rotary spark gap with a hydrogen thyratron in the magnetron
modulator was the main improvement, but it came with some troubles; as the available thyratrons
could not pass enough current, they
were connected in parallel, which
naturally required their careful selection in terms of electrical characteristics.
The transmitter peak power and
pulse width remained practically
unchanged in comparison with the
NYSA-B, but the PRF was conFigure 12.
siderably higher. A travelling wave
Top left. BOGOTA height finder. Top right. Sinusoidal potentiometer used in the NYSA-B and BOGOTA
tube (TWT) was employed in the
height finders. Bottom left. Mechanical height indicator of the BOGOTA height finder. Bottom right.
receiver front end, improving the
JAWOR-M air defence radar-entirely new appearance and improved range performance: 180 km on
MIG-17 fighter and 250 km on IL-28 bomber.
noise figure by ca. 3 dB. With such
improvements, the range performance obtained in the acceptance
trials was 185 km on an IL-28 aircraft. The R-H scope remained
noticed in the photographs (Figures 12-14), and a much improved
with its mechanically driven height marker line. Importantly the
performance. It had a new, 9 m wide antenna with an azimuth
azimuth drive performance was improved, so the antenna could be
beam width of 1.8° and the side lobe level reduced to -20 dB acslewed to the opposite azimuth in only 7 seconds (compared with
cording to the technical specification. The antenna rotated at 3, 6,
20 s for the NYSA-B). The antenna with its vertical drive and the
or 9 rpm. The element visible at the end of the reflector is a beacon
whole cabin remained unchanged, so the BOGOTA and NYSA-B
receiving antenna. Along with the IFF system, a beacon system
looked outwardly the same (Figure 12, top left).
was in use at that time. In the beacon system, unlike in the IFF,
The JAWOR and BOGOTA radar sets were manufactured over
aircraft were interrogated with primary radar radiated pulses, and
the period 1963-66 at RAWAR, with a total of 66 sets supplied to
airborne transponders responded at another fixed frequency. By
the Polish Air Force.
these means, the effective range of locating friendly aircraft could
be extended far beyond the primary radar range.
The JAWOR-M transmitted 1.2 MW of peak power with
IMPROVED VERSIONS OF THE JAWOR AND BOGOTA
pulse width of 3 μs or 1.5 μs and the PRF lower or higher, respectively. The receiver noise figure was 7 dB. Two systems of
When the JAWOR and BOGOTA sets were in series production,
automatic gain control (AGC) were implemented: noise sensiimproved versions of both radars were in development, resulting
tive AGC and the so called immediate AGC, the latter reacting
in the JAWOR-M search radar and BOGOTA-M height finder, the
to instantaneous signal amplitude rather than the noise level,
production of which started in 1967. The improvements in both
preventing receiver overdriving by strong echoes. The MTI
cases were significant. When compared with its predecessor, the
system was totally upgraded through the use of storing tubes
JAWOR-M (a common development project of PIT and RAWAR)
instead of mercury delay lines. Storing tubes played a very imfeatured a distinctly more modern appearance which can be easily
54

IEEE A&E SYSTEMS MAGAZINE

JUNE 2017

Table of Contents for the Digital Edition of Aerospace and Electronic Systems Magazine June 2017