ALP-100 Log Periodic Antenna
Theory of Operation
3
This chapter explains the following:
a)
Overview
b)
Theory of Operation
Functional Block Diagram
3-1
3.0 Overview
This section describes the theory of operation of the ALC-100 Log Peri-
odic 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. It is very useful for sweep measurement over the
frequency range of operation. Model ALC-100 Log Periodic Antenna is
a broadband antenna that operate in the frequency range of 300 MHz to
1000 MHz.
antenna is a receive only antenna. It cannot transmit signals. However,
Model ALC-100 antenna can both receive and transmit signals over the
frequency range of operation. Model ALC-100 antennas are used for
susceptibility and emissions testing in EMC Laboratories.
Before the Log Periodic Antennas are used for measurement they have to
be calibrated. Typically antenna calibration is performed in an open fi eld
test site( OATS). During calibration a known fi eld strength (dBuV/m) is
generated around the antenna at each frequency (300 -1000 MHz). The
difference between fi eld strength (dBuV) received by the antenna and
known fi eld strength generated ( dBuV) is the antenna factor (dB) 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 measure fi eld strength.
dBuV/m
(fi eld strength) = dBuV (output measured) + Antenna Factor
