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14.8 Fresnel Zone
Radio Frequency (RF) line of sight is required to achieve maximum range with the
Spectra radios used with the Jerome 451/651 instruments. RF line of sight differs from
visual line of sight as shown in the figures below. The Fresnel Zone is an elliptical
volume of space between the two antennas. Any objects within this space block a
portion of the signal, and the radios are not able to transmit to their maximum range.
If the antennas are low enough, the ground itself blocks part of the signal.
Placing the antennas higher up will prevent the ground from entering the Fresnel zone
and improve the radio signal.