Aerospace and Electronic Systems Magazine June 2017 - 50

Early History of Polish Radars
the operator of the interfaced NYSA-B height finder. The whole
radar equipment required ca. 11 kW of prime power.
The maximum range of the NYSA-C radar was reported as
reaching 300 km on a 10 m2 target when in slow scanning mode.
The maximum height of detection was 15 km. Again, the way the
range performance in the "slow scanning" mode was defined undoubtedly added some extra kilometres to the true range available
in normal operation mode. No doubt this radar, much like its predecessor, suffered from too low transmitter power or, more generally,
energetic potential. Indeed, the average transmitter power was only
200 W per antenna; with the available noise figure of 11 dB, not
very much range performance could be obtained.
Calculations show that with a scan rate of only 3 rpm, a maximum free-space range of about 160 km on a 10 m2 target, or some
120 km for a 3 m2 target, could be reached, assuming the rigorous detection performance required today (detection probability of
80% and false alarm rate 10-6). However, at the very beginning
of radar development radar operators were not so demanding regarding the quality of the radar picture, and none of them would
have even dreamed about a false alarm rate as low as 10-6, so the
reported ranges could be comparatively longer.
As the first Polish military warning radars came into being,
the problem of identification "friend or foe" (IFF) arose as well.
The Soviet KREMNI-1 system was in use at that time in its first
version, originating very probably from an earlier design of German origin. Operating at around 170 MHz, the IFF equipment was
too bulky (with primary radar equipment itself bulky enough) to
fit into the radar cabin. The NYSA-C radar therefore used selfcontained IFF equipment deployed on another truck, with a Yagi
antenna on the cabin roof. A photograph of that equipment is given
here (Figure 6, bottom).

NYSA-B HEIGHT FINDER

Figure 6.

Top. NYSA-C warning radar. Bottom. KREMNI-1 IFF interrogator to
accompany NYSA-C radar.

use of a parabolic cylinder (instead of fully paraboloidal reflector)
simplified the mechanical design of the reflector itself, but complicated the illumination system; to form a beam with suitably low
side lobes, the weighting coefficients of the power divider supplying the dipole radiators had to be carefully chosen. On the other
hand, the requirements concerning the side lobe level were not
very exacting at that time; a relative side lobe level of -15 dB was
an acceptable figure. Azimuth scanning was provided by rotating
the whole cabin with the antennas and the transmit/receive system
inside. The scan rate could be adjusted from 0.5 to 6 rpm.
Apart from the antenna-transmit-receive cabin, the radar included a truck based operation shelter, where a PPI, an A-scope,
a plotting board, and a working station for a radio and telephone
operator were placed, as well as a range-height (R-H) display for
50

The NYSA-B was dedicated as complementary to the NYSA-C warning radar, providing the height of detected targets. This height finder
could detect an IL-28 aircraft (its RCS estimated as 6 m2) at a range
of 100 km, with the accuracy of height measurement around 700 m.
The NYSA-B operated in the S-band, with a magnetron transmitter of 1 MW peak power, pulse width of 1 μs and pulse repetition frequency (PRF) of 200 Hz. Modulating pulses were produced
in a line-type modulator with a rotary spark gap. The paraboloidal
reflector antenna produced a pencil beam of 4.3° in azimuth and
1.3° in elevation. The antenna mechanically scanned the elevation
sector from -2° to +30° with an adjustable rate of up to 10 nods per
minute, while the whole cabin was slewed in azimuth according to
the requests coming from the NYSA-C search radar. There was no
operator in the height finder cabin, the height measuring process
being controlled by the operator sitting in front of the R-H indicator in the NYSA-C surveillance radar shelter (Figure 7).
The R-H display featured a cathode ray tube (CRT) 7 inches in
diameter. The R-H picture was produced using fixed deflection coils.
Vertical deflection followed the sine of the antenna elevation angle
by means of a special sinusoidal potentiometer whose shaft was
geared with the nodding antenna. The use of a sinusoidal potentiometer simplified the process of producing the R-H picture (Figure 12).

IEEE A&E SYSTEMS MAGAZINE

JUNE 2017

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