Antenna gain measurement by standard antenna method

Introducing the antenna gain measurement method by the standard antenna method using the radio anechoic box

Application

Evaluating antenna gain usually requires a calibrated standard antenna or anechoic chamber, but it can be simply evaluated using a spectrum analyzer with a tracking generator and a radio anechoic box.

Obtain the EUT gain by comparing it with the reference antenna (antenna with a known gain).
As for the measurement environment, the measurement is performed in the anechoic chamber (anechoic box) as in the case of radiation pattern measurement.
Mainly, dipoles and log periodic antennas are used in the MHz band, and horn antennas are used in the GHz band.

Solution

Measurement procedure

Set the spectrum analyzer center frequency and span according to the band you want to measure.
The tracking generator output is measured at the reference antenna end.【Fig.1】
The result is "A (dBm)"
Prepare a receiving antenna and a reference antenna (Tx), and install them in the anechoic box at a certain distance.
Close the door of the anechoic box and perform the measurement.【Fig.2】
The result is "X (dBm)".
Take out the reference antenna (Tx) and install the EUT in the same position.
Close the door of the anechoic box and perform the measurement.【Fig.3】
If you do not know the maximum radiation direction of the EUT, rotate the turn table and look for the peak gain.
The result is ""Y (dBm)"".
Calculate EIRP EUT (dBm) from the following formula.
EIRP Tx(dBm)＝A(dBm)＋Gain Tx(dBi)
EIRP EUT(dBm)＝Y(dBm)－X(dBm)＋EIRP Tx(dBm)
Obtain the EUT gain from the following formula.
Gain EUT(dBi)＝EIRP EUT(dBm)－EUT transmit power(dBm)

※EIRP：Equivalent Isotropically Radiated Power
※If the EUT transmission power and gain cannot be separated, such as when the EUT antenna is integrated, EIRP will be the final result.