Authors
Barellini A, Bogi L, Licitra G, Silvi AM, Zari A. (2009). Measurement of electromagnetic fields generated by air traffic control radar systems with spectrum analysers. Radiat Prot Dosimetry. 137(3-4):210-3.
Introduction

Air traffic control (ATC) radar ground station includes two radar systems; a primary surveillance radar (PSR) and a secondary surveillance radar (SSR). Peak power transmitted by secondary surveillance radars is usually less than one thousandth than irradiated by primary surveillance radars. Air traffic control primary radars use radiofrequency (RF) pulses from aircraft to locate it. Long-range primary surveillance radars use a frequency band between 1 and 2 GHz. High-power pulses radiated from primary surveillance radar antennas may produce high electromagnetic field (EMF) levels in the vicinity.

Objectives
The objective of the study was to measure EMF produced by RF-pulsed radar by means of a swept-tuned spectrum analyser method.

Methods
In the study, the authors used a method called spectrum analyser (SA) or a vector signal analyser connected to an antenna by means of a coaxial cable. These analysers allowed measurement of radar parameters both in the frequency and time domain. These instruments allowed measurement of field strength but are not able to measure radar parameters such as pulse width and repetition time. In this study, measurements through a narrow band instrumental chain supplied with a swept-tuned spectrum analyser were assessed. Laboratory measurements have been carried out by means of an spectrum analyser “Agilent ESA mod”. In situ measurements have been carried out near an air traffic control primary surveillance radar. The radar transmits in L band with a carrier frequency of about 1.3 GHz, a pulse width t of 2.8 ms and a PRT of 2.2 ms.

Results
Results indicate a deviation up to 0.5 dB in the laboratory and 0.7 dB in situ in both in line spectrum and pulse spectrum modalities.

Interpretation
Measurements were conducted both in the laboratory and in situ on radar signals produced by primary surveillance radar for air traffic control. Results showed deviations up to 0.5 dB in the laboratory and 0.7 dB in situ in both modalities, except for RBW values in the range 0.2/t, RBW, 1/t and for RBW ¼ PRF. Obtained deviations could be reduced even more using experimental parameters for the calculation of desensitising factors rather than the factory data or data provided by radar manager, such as pulse width and pulse repetition rate.

Conclusion
Results confirm that a good accuracy may be achieved both in line spectrum and pulse spectrum modalities.

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