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Technical Topics => Equipment => Topic started by: OgreVorbis on July 13, 2020, 0817 UTC

Title: Higher highs and lower lows on MW TX antenna
Post by: OgreVorbis on July 13, 2020, 0817 UTC
Compared with a MW broadcasting station, my antenna produces higher peaks and lower troughs at all times and all listening locations. Why is this? Does this have to do with angle of radiation? It is interesting that during the peaks, it's actually better than a number of MW stations at the same distance, but it dips so deep that it can't be heard sometimes. Would making the vertical section longer improve this? I always thought that angle of radiation simply has to do with the distance covered, but maybe it's more than that. If it's not angle of radiation then what is it?
Title: Re: Higher highs and lower lows on MW TX antenna
Post by: Stretchyman on July 13, 2020, 1140 UTC
Via Groundwave or Skywave? Day or night? What antenna type and dimensions?

Str.
Title: Re: Higher highs and lower lows on MW TX antenna
Post by: Brian on July 13, 2020, 1238 UTC
Too little information.
Are you comparing SW with MW?
Title: Re: Higher highs and lower lows on MW TX antenna
Post by: OgreVorbis on July 13, 2020, 2019 UTC
Via Groundwave or Skywave? Day or night? What antenna type and dimensions?

Str.

Skywave only. Night. Antenna is 1/4 wave inverted L 60-70 ft tall, the rest horizontal.

Too little information.
Are you comparing SW with MW?

No, I'm comparing MW with MW. I wouldn't compare with SW cause that would be different.

Either way, it's not really a problem, but I find it very interesting. It's not what I would expect.
Title: Re: Higher highs and lower lows on MW TX antenna
Post by: Josh on July 14, 2020, 1723 UTC
Perhaps modulation schemes are different per station?
Title: Re: Higher highs and lower lows on MW TX antenna
Post by: Stretchyman on July 15, 2020, 0618 UTC
As the fades are due to fluctuations in the D layer I'm surmising that a shallower angle of inclination may help as the signal is going to spend less time in the layer? Just guessing but a worthwhile experiment. This is what those online SDRs are for! Maybe try NVIS to see the difference too...

I now have a local SDR at 30 miles to the west on the far side of a hill and want to see how I can improve my ground wave on 1.5 MHz. Fortunately no ionosphere to deal with!

What kind of distance are you getting on  a single hop at night? What's your power?

Str.