# Non-Ionizing Radiation Measurements for Trajectory Radars
## 1 Introduction
### Related Works  
A survey was carried out on the Scopus database, using the following keywords related to the matter: \"radar\" and \"non-ionizing\" and (\"radiation\" or \"NIR\" or \"electromagnetic field\" or \"EMF\" or \"measurement\"), looking in the title, abstract and keywords fields. Considering the last 50 years, 93 publications were found. Among them, 46 publications have no direct relationship with radars; 35 are related to handheld radars mostly used for cancer detection and other health analyses, but they are not related to NIR studies [5; 6; 7]; 9 are radar and NIR related, but measurements were not performed [8; 9; 10]; and only 3 contributions carry out studies on NIR radar measurements (air traffic control and ship-board navigation radars) [11; 12; 13]. One of the reasons for the small number of publications in this area is the restricted access to this type of radar. There were no studies found about measuring non-ionizing radiation due to trajectography radars, evidencing that probably this is the first work to do so. References [11; 13] are focused on radars and clearly describe the setup, so they were chosen to be summarized next. In [11] a measurement campaign is carried out involving 14 types of air traffic control systems, including a Weather Radar (WR) and three types of aircraft tracking radars. Two of them are the Primary Surveillance Radar (PSR) and the Secondary Surveillance Radar (SSR) used together for long-range scans. The third type is the Surface Radar (SR) which is a short-range radar, often placed in a control tower, used to scan the lower layers of the air and the movement of planes on the ground. The PSRs are L-band and S-band; SSRs are L-band; the SRs are X-band and Ku-band; and the WR is C-band. These types of radars continuously rotate their antennas horizontally, so the NIR levels are not constant. For this measurement, a Rohde and Schwarz HF907 OM omnidirectional antenna for large frequency bands (800 MHz-26.5 GHz) was used in combination with a Rohde and Schwarz spectrum analyzer of the FSEM type. The results show that no limits established by ICNIRP were exceeded, both for the general and occupational public. In [13] NIR measurements are performed aboard a marine vessel with seven different transmitters. Two of them are X-band and S-band radars, used for navigation purposes. For that, a NARDA NBM 520 with an EF 1891 probe (frequency range 3 MHz-18 GHz) are used. The probe is an isotropic one, providing non-directional measurements. A method to collect the measured data is proposed, considering the different sources transmitting at different times. Considering ICNIRP specifications, both general and occupational public limits are respected for all measured locations in the ship when the transmitters are operating separately. However, when both radars, satellite communication, automatic identification system navigation and VHF radio are operating at the same time, the limits for the general population are exceeded on the bridge roof. Radar NIR measurements are generally carried out with isotropic probes, as performed in [11; 13]. This is because most radars have antennas that work continuously in rotation or scanning mode, unlike trajectography radar which points the antenna in the chosen direction and at any time. With this type of probe, it is impracticable to measure the power density of signals exclusively from the radar, unless it is in an isolated area and it's the only transmitting source, which is generally not the case for ground radars. CLBI's radars, for example, receive interfering third harmonic signals from mobile communication base stations located in different positions around the radars. To deal with this situation, considering the high directivity of trajectography radar antennas for accurate tracking of unique targets, a specific measurement method for this type of radar is proposed here. This work is organized as follows. Section 2 presents the Anatel Act No. 458 and the national and international established limits regarding human exposure to NIR.