Tektronix 2706 Instruction Manual page 28

Applications
Radiated EMI Testing
Susceptibility Testing
Benchtop Analysis
4–2
The Preselector, with appropriate antennas and other equipment, can help your
spectrum analyzer measure EMI radiated from a particular device. The Preselec-
tor attenuates radio and television transmissions and other RF interference
outside the range of interest. Test setups use one of three basic antenna types:
H tuned dipole: used to measure radiated EMI in the 30 MHz to 1000 MHz
range. Different balums and adjustable dipole elements cover the entire
frequency range.
H biconical: used to measure horizontal and vertical polarization of radiated
EMI in the 30 MHz to 300 MHz range. Use a biconical antenna (Tektronix
part number 119–4148–00 or equivalent).
H log periodic: used to measure horizontal and vertical polarization of radiated
EMI in the 200 MHz to 1000 MHz range. Use a log periodic antenna
(Tektronix part number 119–4142–00 or equivalent).
Once you determine the frequency and strength of the radiated EMI, you can
take appropriate corrective action or note the results for specifications.
A spectrum analyzer, with the Preselector, can monitor field strengths during
susceptibility testing.
CAUTION. To avoid damage to the Preselector and your spectrum analyzer, do
not connect signals higher than +20 dBm or 50 VDC to the Preselector.
The Preselector can improve the frequency response measurement of a circuit or
devices such as cables, mixers, amplifiers, and IF bandwidth chains by passing
only the frequencies you want to the spectrum analyzer. (This is especially useful
if you are using a broad-band noise source.)
2706 RF Preselector