Sporadic-E signal levels

The Sporadic-E is the strongest available propagation mode. An ionized “cloud” acts like a metal reflector, that allows signal to skip over a huge distance. It is possible to receive many stations with just a small portable radio and a telescopic antenna. With better equipment, when the frequency is clear, it is also possible to receive stations that transmit at extremely low power, like 50W, with full RDS and stereo! So, the signal level must be really strong, but how strong?

Today during a massive Sporadic-E opening BBC Radio 2 peaked once to 72dBf signal on Körner 19.3 (114m asl + 10m agl).

Körner 19.3 has 9dBd gain on 89 MHz. Assuming that BBC Radio 2 came from the Holme Moss TX with 250kW ERP, we can calculate the following values:

ERP Signal (Körner 19.3)  Signal (dipole)
250 kW 72 dBf 63 dBf
100 kW 68 dBf 59 dBf
10 kW 58 dBf 49 dBf
1 kW  48 dBf 39 dBf
100 W 38 dBf 29 dBf
10 W 28 dBf 19 dBf
1 W 18 dBf 9 dBf
100 mW 8 dBf -1 dBf

Yup. With high gain antenna, like Körner 19.3, 1W can still produce RDS level via Sporadic-E propagation, depending on the subcarrier injection level. 100mW ERP at 8dBf is audible quite well above the noise floor at peak!

One thought on “Sporadic-E signal levels

  1. Akurat wczoraj udało mi się złapać kilka stacji z GB, Francji i 1 z Włoch. Na żadnej nie udało mi się znaleźć ID stacji.

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