L. Anglesio

Experimental Setup for the Characterization of Field Probes Performance in Presence of Digitally Modulated Radio Signals

Field probes are widely used for radio-frequency electromagnetic-field exposure assessment. Nevertheless, several authors point out measurement uncertainties when the signal under test is digitally modulated. In this letter, the main drawbacks emerging from the use of probes to measure complex modulations are analyzed and discussed. Consequently, an experimental setup is introduced and investigated to verify probes performance and to allow an easy and usable evaluation of the uncertainty.

Field Probes Performance for the Measurement of Spread-Spectrum Radio Signals

This letter describes results obtained from an experimental evaluation of field probes used to assess digitally modulated electromagnetic fields. Making use of an experimental setup specifically developed, a large number of devices with different characteristics were analyzed in the presence of three different spread-spectrum schemes: wideband code division multiple access [(W)CDMA], direct sequence spread spectrum (DSSS), and orthogonal frequency division multiplexing (OFDM). The measurement error caused by the modulation was investigated as a function of its main parameters: signal power, time variation, and occupied bandwidth.

Measurement of Spread-Spectrum Radio Signals by Means of Wideband Field Probes

Field probes have been widely used, in the literature, for electromagnetic compatibility measurements and electromagnetic interference estimation. In the last two decades, these instruments have been exploited for open-space electric field exposure assessment, thanks to their ergonomics and capability to adapt to any scenario. This paper analyses the behaviour of field probes, in presence of digital spread-spectrum signals: OFDM (802.11a, 802.11g, 802.16x, DVB-x), W-CDMA (UMTS), DSSS (802.11b). The experiment was set-up in controlled environments, and the results were compared to referenced one, measured by means of bolometers or vector signal analysers. Some structural drawbacks were identified. Consequently, some conclusions about calibration needs were introduced.

Radiofrequency measurements for human exposure assessment in indoor environment

Because of reflection and diffraction phenomena, radiofrequency electric field pattern in indoor environment is very complicated showing rapid spatial variations of field strength values. In this context, measurements have to consider the presence of conductive surfaces and objects which can cause effects of coupling with survey meters and antennas. In this paper data about indoor measurements carried out in different indoor sites, both by broad band and narrow band instrumental chains, are shown. Comparison of data obtained with the different measurements methods is discussed and the influence of indoor environment on radiofrequency field human exposure assessment is analyzed.