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[2E0SVE]

I am still quite a bit of. newbie.  I have a quesiton about LW and MW.  I was told that LW relies a lot on ground wave propogation long back when I did the my radio course.  Yet most LW adn MW radios have simple ferrite wound antennas.  If LW is ground propogation why do we not have antenna pointing or in the ground.  Secondly what attenuates the gignal is a particuar land form more attenuating or less.  I have had many people they for example often ger BBC Radio 4 on LW 198 kHz in Germany, but recent trip to Denmark and Sweden I could get very little at all.  On a good day with tropospheric reflection I got Absolute radio before it switched off its AM recently, but, I am perplexed at no LW at all.  I am wondering if it all the igenious rock attenuates the signal in a way that does not say affect germany or if what I was told is true at all.

Assistance greatly received.

Regards

[W1VT]

http://radio-timetraveller.blogspot.com/2011/01/unassuming-antenna-ferrite-loopstick.html
Here is a good presentation that doesn't get overly complex.

A loopstick is a very practical antenna for receiving vertically polarized LW and MW antennas.
It has a very sharp null which may be used to get rid of interference by rotating the radio for best reception.

[VR2AX]

Ground wave signals follow the ground for short distance compared to sky wave. Usually sent by comparative short verticals and big power to make up the ground loss.

Droitwich was the standard in UK, 1500 metres, about 200kHz, there were also one or two close EU stations. The site I think now dismantled was in the west Midlands around Worcestershire.

Am as in US usually refers to MW. That usually gave added skyway in the night, Radio Caroline, Luxembourg..

I think the ferrite rod antennas capture the magnetic field of the wave rather than the electric field but others may comment

[WA3SKN]

OK, there is ground wave, direct wave, and sky wave propagations.  However, first... what time of day (or night) are you listening?

-Mike.

[2E0SVE]

OK, there is ground wave, direct wave, and sky wave propagations.  However, first... what time of day (or night) are you listening?

-Mike.

I am interested in the principle of ground wave and whether what I was told is correct.  Generally I listen in the evening.  I had assume this is not to do with troposphic propogation.  I was focusing on the ground wave element and in particular why my experience was as it was.  So the question can be for all hours of the day.

73

[W1VT]

https://www.bbceng.info/additions/2016/No.%2010%20-%20Long-Wave%20And%20Medium-Wave%20Propogation.pdf

I don't do LW listening, but 80M ground wave does seem to be enhanced by traveling along rivers, as opposed to dry ground.
You may be seeing the effect of some long distance listeners having all water paths, while it may take relatively little dry ground to block a path.
Those on the CT shoreline have much better propagation than those inland from effects like these.

[WB6BYU]

Ground wave (or "surface wave") attenuation with distance
is a function of soil conductivity, because the radio wave
induces currents in the ground.

Looking at the CCIR tables for ground wave propagation,
a 1 kW transmitter at 200 kHz gives a signal strength of
1uV/m at 2000 km over sea water vs. 800 km over poor
ground.  (Assuming my eyes could read the graphs
properly.)


Why don't we point the antenna at the ground?  The
"surface wave" signal is confined in the space between
the surface of the earth and a height of roughly one
wavelength above it.  We're not picking it up from the
ground, but rather the wave travels along the earth/
air boundary.  A vertically polarized antenna is optimum
for both transmitting and receiving.

There may be other factors, including the orientation of
the loop antenna, or local noise levels, that affect the
received signal strength, but the intervening ground
between you and the transmitter certainly makes a
difference.