Hi Roger,

 

calculating ERP...

 

Using 1/r^3 from 10 m to the radiation field boundary at 0.8 km, we get

 +72 - 3 * 38 dBuA/m = -42 dBuA/m,

then proceeding with 1/r to 1 km and multiplying by 377 ohms

 H = -42 - 2 = -44 dBuA/m, E = 7.5 dBuV/m,

deriving radiated power and ERP

 EMRP = 7.5 - 49.5 = -42 dBm = 63 nW,

 ERP = 115 nanowatts.

 

... not much is it?

 

Anyhow using very slow modes, you might be able to make several tens or even 100 kilometers on daytime groundwave.

 

Best 73,

Markus (DF6NM)

 

 

-----Ursprüngliche Mitteilung-----
Von: Roger Lapthorn <[email protected]>
An: rsgb_lf_group <[email protected]>; rsgb_lf_group <[email protected]>
Verschickt: Di, 28 Jan 2014 12:28 pm
Betreff: LF: 73kHz in the UK?

Is my reading of the UK frequency allocation chart right?

One can operate without a licence in the old 73kHz band using licence-exempt inductive devices rules as long as the output is less than 72dBuA at 10m? Not sure what sort of ERP this equates to. A few uW I assume?

Perhaps someone can advise/confirm.

73s

Roger G3XBM