Path Loss Calculation; Positioning The Dut (Device Under Test); Figure 1: Anechoic Chamber - Sierra Wireless MC5720 Hardware Integration Manual

R F I n t e g r a t i o n

Figure 1: Anechoic chamber

Agilent 8960
call box
Approx . 1 m

Path loss calculation

The chamber is calibrated for path loss using a reference antenna with known
gain that is feeding a spectrum analyzer or power meter. This makes it possible to
determine the radiated power available to the receiving antenna, which is equal to
the measured received power, plus any cable losses, minus the gain of the
reference receive antenna. Path loss is then determined by subtracting the input
power. It is not necessary to know the gain of the transmitting antenna; it is
included in the path loss.

Positioning the DUT (Device Under Test)

To achieve meaningful results, the device must be positioned such that the peak
of the receive antenna pattern is pointed toward the source antenna.
Theoretically, the best way to accomplish this is to modify the DUT so that
antenna output is through coaxial cable. The device is then rotated until the
receive power is maximized.
Path loss can also be calculated without modifying the DUT by using the
transmit capabilities of the unit. This method of calculation is possible because
the position that maximizes transmitter power provides a sufficiently accurate
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