Hi folks,
This is just a comment. I recently wrote a short story
for the Finnish SRAL magazine about Field strength
measurements - which we have been doing for over 40 yrs.
We have been flight measuring most Finnish NDB/Locator
beacons and all Finnish and Swedish DGPS beacons.
Most powerful I've ever seen in N. Europe is Tallinn
"LK" 386 kHz radiating abt 30 W. Of 105 Finnish NDB
/Locators most (Tx=500W) radiate between 8-12 W,
some even 15 W, using a 14 m high top loaded monopole.
I made some EMRP calculations for OH1TN who is located
152 km from my place. Can hear him daily as ground wave.
For 136 kHz sigma I use 0.5 mS/m, for 300 kHz 1 mS/m.
Reino's EMRP can be anything between 10 mW and 50 mW.
Hope some day we can make some real field measurements.
I have at home an old Anritsu Field strength meter but
its sensitivity / selectivity is not good enough.
Can only estimate that his real Fs is less than 10 dBuV/m.
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GROUND WAVE FIELD-STRENGHT, MILLINGTON METHOD
OH1TN -> OH2LX, Ground distance = 152 km
FIELD-STRENGTH DB ABOVE 1 MICROVOLT/METER
EPS =10.0 SIGMA = .5 mS/m FREQ = 136. kHz POWER = .05 W
DIST. (KM) F-S (DBU)
1.0 66.3
2.0 60.2
3.0 56.5
4.0 53.9
5.0 51.9
6.0 50.2
7.0 48.8
8.0 47.5
9.0 46.4
10.0 45.4
30.0 33.9
50.0 27.2
70.0 22.6
90.0 18.8
110.0 15.7
130.0 12.8
150.0 10.2
170.0 7.8
190.0 5.6
210.0 3.5
END OF CIRCUIT
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V.K.Lehtoranta, OH2LX, POBox 50, FIN-05401 Jokela, Finland
------ Tel: +358-9-4173965 ---- Fax: +358-9-4173961 ------
E-mail: [email protected] - alias: [email protected] & [email protected]
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