Microwave performance evaluated by signals received from the
beacons at Shiphol Airport PI7EHG :
Measurements done on a nice "dry" day 20010421
| PA5DD (JO22IC22) | 2320 MHz | 3400 MHz | 5760 MHz | 10368 MHz | 24192 MHz |
| PI7EHG/B (JO22JH14) EIRP | +40 dBm | +39 dBm | +49 dBm | +32 dBm | +26 dBm |
| Path gain (25km) | -99 dB | -99 dB | -99 dB | -99 dB | -99 dB |
| = | |||||
| Power density at RX antenna | - 59 dBm/m² | - 60 dBm/m² | - 50 dBm/m² | - 67 dBm/m² | - 73 dBm/m² |
| RX antenna aperture (ideal) | - 4 dB/m² | - 4 dB/m² | - 4 dB/m² | - 4 dB/m² | - 7.5 dB/m² |
| = | |||||
| Power at RX input | -63 dBm | -64 dBm | -54 dBm | -71 dBm | -80.5 dBm |
| Noisefloor @3kHz,290K,NF=0dB | -139 dBm | -139 dBm | -139 dBm | -139 dBm | -139 dBm |
| <> | |||||
| Ideal free space S/N@3kHz | 76 dB | 75 dB | 85 dB | 68 dB | 58.5 dB |
| Measured S/N@3kHz | 60 dB | 60 dB | 55 dB | 56 dB | 39 dB |
| <> | |||||
| Difference ideal to measured | 16 dB | 15 dB | 30 dB | 12 dB | 19.5 dB |
| Calculations | Unit | |
| PI7EHG Beacon EIRP | 10 * Log [power in mW] + TX antenna gain (dBi) | dBm |
| Path gain | -10 * Log (4 * pi * [distance in meters]²) | dB |
| = | ||
| Power density at RX antenna | dBm/m² | |
| RX antenna aperture (ideal) | 10 * Log (pi * [parabol radius in meters]²) | dB/m² |
| RX antenna gain | [aperture in dB/m²] + 10 * Log ((4 * pi) / [wavelength in meters]²) | dBi |
| = | ||
| Power at RX input | dBm | |
| Noisefloor@3kHz,290K,NF=0dB | 10 * Log [bandwidth in Hz] - 174 dBm/Hz | dBm |
| <> | ||
| Ideal free space S/N@3kHz | dB | |
| Measured S/N@3kHz | dB | |
| <> | ||
| Difference ideal to measured | dB |
Note: The values for ideal free space propagation assumes no losses by refraction, reflection or atmospheric losses. It also assumes ideal illumination of the receive antenna, no transmission loss between antenna and receiver, and finally assumes a receiver noise figure of 0dB. The values are only relevant for a relative comparision with the measured values.