```Hello Jim & group, ```G3NYK (6m high, 30m long inv. L): Rloss = 4733/f^0.86 (for points below 600kHz only) ```M0BMU(8m high, 40m long inv. L): Rloss = 1550/f^0.75 ZL2CA(Don't know, but must be quite big!): Rloss = 142/f^0.50 ``````While doing research for my LF antenna webpage I came across a formula the gave the pentration depth of an E-field in the soil as : ``` D = 509/(S^0.5*F^0.5) where D = depth in m, S = soil conductiviy in S/m and F = frequency in Hz ```Assuming the the ground loss is proportional to the distance 'traveled' through the soil the results of Bob (ZL2CA) seemed really a textbook case compared to the measurements of Jim (MBMU) and Alan (G3NYK), so I wonder if the 2 last do suffer more from additional losses (buildings and greenery close to the antenna) compared to Bob ? BTW : The emperical equations are a bit dependent on the frequency range you take. For Jim's measurements I get R = 1555*F^-0.75 for the whole range but then I took only the points between 100 and 300 kHz (to have the same range as Bob) and got R = 1830*F^-0.79. 73, Rik ON7YD ```