AH-840 Horn Antenna
Theory of Operation
3
This chapter explains the following:
a)
Overview
b)
Theory of Operation
3-1
3.0 Overview
This section describes the theory of operation of the Horn Antenna.
3.1 Theory of Operation
Broadband antennas allow measurement of signals over a wide frequency
range. These antennas do not require any tuning or balun switching during
measurement. Models AH-840 Horn Antennas are broadband antennas that
operate in the frequency range of 18 GHz - 40 GHz.
The model AH-840 can both Receive and Transmit over the frequency
range of operation and is used for susceptibility and emissions testing in
EMC Laboratories.
Before the Horn antennas are used for measurement they have to be
calibrated. Typically antenna calibration is performed in an open field test
site( OATS). During calibration a known field strength (dBV/m) is
generated around the antenna at each frequency at predetermined intervals
between 18 GHz - 40 GHz. The difference between field strength (dBV/m)
received by the antenna and known field strength generated ( dBV/m) is
the antenna factor (dB/m) for that frequency. During EMC testing the
antenna factor for the frequency of interest is added back to reading on
the EMI meter or spectrum analyzer to calculate the field strength
measured by the antenna.
Field strength (dBv/m) = Output measured (dBV) + Antenna Factor (dB/m)
When using the AH-840 antenna for transmitting application, please refer
to Table 1-2 to determine the power requirements to generate the desired
electro magnetic field.
