Do you know How to Measure Gain?

Measuring gain:
The gain of an antenna is measured in relation to the gain of another further specified antenna through a comparison measurement.

The latter antenna is called a reference antenna and the reference antenna is different, irrespective of whether base station antennas, mobile antennas or portable antennas are considered.

EIA RS-329-1 Standard for Base Station and Mobile Antennas:
EIA RS-329-1 is an internationally valid standard for measuring gain for base station and mobile antennas.

According to this standard the gain of base station antennas is specified compared to a ½ wave dipole and the gain of mobile antennas is specified compared to a ¼ wave whip in the centre of the car roof.

No international standard for portable antennas.

No international standard for measuring gain of portable antennas is available. Normal practice is, however, to apply a ”¼ wave antenna on same device” as a reference antenna.

Owing to the indefinable ground plane, which a hand-held radio constitutes, it is necessary to perform statistical average value calculations for a large number of measurements in order to be able to state the gain of a portable antenna rather precisely.

CCIR 368.3 Standard for Medium and short Wave Antennas:
Medium wave and partly short wave maritime antennas are measured in accordance with the international standard CCIR 368.3. The reference antenna is in this respect a ¼ wave monopoly antenna above water, as for which calculated field strength is determined as function of the distance from the antenna when applied with a certain power.

Measuring and Calculating:
By measuring the gain of an antenna, a signal of a known size is applied and the field strength is measured at a certain distance. By calculating back it can be figured out to which degree the antenna has (generally) a poorer performance compared to the reference antenna. Gain will in such cases be specified as an efficiency.

Antennas for maritime VHF are measured like base station antennas.