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User manual
Antenna model: AT3000
Rev 6.0 – September 2014
Clampco Sistemi is a registered trademark of
Calzavara SpA
– via Corecian, 60 – 33031 – Basiliano (Italy) http://www.clampco-sistemi.com/
3.3. Antenna impedance
The diagram below represents the typical return loss coefficient of the receiving antenna AT3000 measured at the
antenna port with all available axis selection.
Figure 8
: AT3000 return loss at the antenna port (typical)
As one can see it is low enough to get negligible error due to stationary waves in the RF cable, provided that the
receiving instrument has an acceptable impedance match. Generally this is not necessary but, in order to verify the
possible presence of stationary waves in the coaxial cable used, it is possible to set a minimum value for the
internal attenuator of the spectrum analyzer , typically 5 or 10 dB, and compare the result.
3.4. Sensitivity
Selective field measurements normally rely on a “display” instrument with a wide range of setting possibilities: the
spectrum analyzer (SA). It is therefore better to take into consideration the entire measuring system, including the
SA.
Usually, the minimum detectable signal is limited by the noise. Thermal noise has a uniform spectrum distribution
with a value of about –174 dBm/Hz at ambient temperature. Furthermore, the contribution of the SA which
depends on the processing chain of the signal from the sensor input (attenuators, IF amplifiers, sampling
method…) must be also considered. This varies as the state of the analyzer varies (input attenuation, reference
level, sampling method, display filtering, display averages…). Finally, the parameter RBW (resolution bandwidth)
defines the integration interval of the spectral power density. It is usually expressed in terms of dBHz, i.e.,
10log
10
(RBW), where RBW is the resolution bandwidth in Hz.
Summary of Contents for AT3000
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