Updated 18/8 2010, recent information about ASPECT added 1/4

Small target detection from the Next Generation SCANTER 5000 and 6000 Series of radars from Terma A/S

By Jens Chr. Pedersen, Director, Product Portfolio & Innovation, Radar Systems, Terma A/S

The SCANTER 5000 series comprises a new generation of Fully Coherent, Frequency Diversity and Time Diversity, Solid State Radars with Software Defined Functionality for professional applications such as VTS, Coastal Surveillance and Airport Surface Move-ment Radars (SMR). Similar technology is employed in the SCANTER 6000 series of radars for Ship-borne applications.

Several tests with targets of opportunity as well as controlled tests were made during the development. This was complemented with a repeated series of trials made during re-lease for operational use of the SCANTER 5102 transceiver in June 2010.

Furthermore, the performance was compared to a SCANTER 2001 FD transceiver in-stalled next to the SCANTER 5102, utilising the same 21’HP-F-38 antenna. Both trans-ceivers were configured for stationary surface surveillance applications. The SCANTER 2001 includes two 25 KW magnetron amplifiers. The SCANTER 5102 is fitted with a 50 W Solid State Power amplifier.

The tests were made at the Terma HQ test range, and with targets sailing in the bay of Aarhus.

Figure 1: Radar image from the SCANTER 5102 at the Terma test site

A 5.2 meter zodiac with outboard motor was used for verification test of the perform-ance. The Radar Cross section was measured to 1.4 square meters and the estimated

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center of gravidity for the RCS is 0.5 m ASL, with the boat driver sitting up. Speed during the tests was varying between 0 and 30 knots, without significant influence on the re-sults. A floating, calibrated reference reflector was placed in the test area at a distance of approximately 4 nautical miles.

Figure 2 Target used for controlled tests.

Figure 3 2 m2 reference reflector used for measurement of target Radar Cross Section during the tests.

The CARPET program from TNO was used to calculate expected range performance, taking actual weather into consideration. Very different weather situations appeared.

� On 07/06/2010 it was very dense rainfall; approximately 50 millimeters of rainfall were recorded during daytime on nearby meteorological stations. The rainfall during the test was estimated to 5 mm/hour, fairly uniform over the entire area.

� On 10/06/2010 it was less dense rainfall; approximately 20-25 millimeters of rain-fall were recorded during daytime on nearby meteorological stations. The rainfall during the test was estimated to 2 mm/hour, not as uniform as on the first day and with cells of dense shower like rain.

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� On 16/06/2010 it was clear sunny weather with a mild breeze.

The rain during the first 2 days was completely removed by processing resulting in an as clear image as on the day with clear weather.

Most of the range between the radar and the test area is over land. Evaporation ducting will in such case only have marginal effect on the propagation and standard atmospheric conditions.

Antenna height at the Terma test site is approximately 50 meters ASL and the waveguide length between the antenna and the transceivers is 22 meters

Calculation and test results are summarized in Table 1.

Table 1 Calculation and test results.

SCANTER

2001 FD

SCANTER

5102

SCANTER

5202

SCANTER

2001 FD

SCANTER

5102

SCANTER

5202

07/06/2010

Aproximately 5

mm/h rain, Sea

state 1-23.7 nmi 4.0 nmi 4.2 nmi 4 nmi 5.7 nmi

10/06/2010

Aproximately 2

mm/h rain, Sea

state 1-24.2 nmi 4.4 nmi 4.7 nmi 5.6 nmi 6.5 nmi

16/06/2010Clear, light breeze,

Sea state 26.0 nmi 5.6 nmi 6.2 nmi 6.5 nmi 7.8 nmi

Calculated detection range with

used Radar setup, 99% Pd

Not

included

in test

Date of test Conditions

Measured detection range @ first

loss of detection

The difference between calculated and measured results for the SCANTER 2001 is in accordance with typical experience, the CARPET calculations are a bit pessimistic.

We have by now observed that the Next Generation radar technology is performing sub-stantially better than expected. The main reason for that is most likely that the empiric models behind the CARPET tools are insufficient in respect to modeling of the new se-ries of SCANTER radars. Looking at the radar screen, target fluctuations are much re-duced with the new technology and this does explain most of the excess performance.

Furthermore, the differences seem to appear in all weather conditions. However, tests with high sea clutter conditions are yet to be completed. In the meantime, evidence is sufficient to allow use of CARPET with SCANTER 2001 FD parameters to determine performance for the 50 W versions, SCANTER 5102 and 5502, of the Next Generation radars in respect to surface target detection.

In respect to the 200W versions, SCANTER 5202, 5602 and 6002, it is OK to calculate with 5% increased range (20% increased volume) when compared to SCANTER 2001. However, BE CAREFULL, the horizon (lowest lobe) may be the limiting factor, in which cases the range performance is identical. This counts especially for low antenna eleva-tions and in clear weather without ducting.

It is in any case better to use the new Terma performance evaluation Tool, ASPECT, it does include better modeling of the new radars and it is being further refined as experi-ence with the new products is gained.

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Figure 4 Test target at 6.1 and 7.4 Nautical Miles respectively