# Calculation of antenna factor and gain

## The calculation equation useful for mutual conversion of an antenna factor and gain is presented.

### ［Application］

Connection block diagram

### ［Solution］

- When measuring the electric field strength by com bining a spectrum analyzer with an antenna, calcul ating an antenna gain from an antenna factor, or the contrary may be needed. The calculation equation is shown below. In MSA438 , the electric field strength can be read directly by registering the antenna gain in it.
- The following equation is used to calculate the ant enna factor Af (dB/m) from the antenna gain Ga (dBi) in a 50-ohm system.

- Similarly, the following equation is used to calcula te the antenna gain Ga (dBi) from the antenna facto r Af (dB/m) in a 50-ohm system.
- The following table is a calculation example.

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Frequency [MHz] | 30 | 50 | 100 | 200 | 500 | 1000 | 1500 | 2000 | 3000 |
---|---|---|---|---|---|---|---|---|---|

Antenna factor [dB/m] | 38.5 | 32.5 | 27.8 | 22.6 | 23.3 | 29.5 | 40.2 | 47.3 | 50.5 |

Antenna factor [dB/m] | -38.7 | -28.3 | -17.6 | -6.4 | 0.9 | 0.7 | -6.4 | -11.1 | -10.7 |

### ［System configuration］

Spectrum Analyzer MSA438 |

MSA438 calibration set |

Biconical Antenna［MAN150] |

*MICRONIX Corporation reserves the right to make changes in design, specification and other information without prior notice.

### ［Products introduction］

2013/3