Jeff Posted February 20, 2022 Share Posted February 20, 2022 Hello So, I'll see if anyone here has a great guess for the question(s) of mine . My friend and I are both amateur radio operators and we discuss propagation daily . About how much it sucks in our locations lol . So whats the scoop ? I do understand it changes from geographic locations but I do not understand how one area can be so radically different than one thats 2 kilometers away ! Is it that selective that this is an actual thing ? Example : My friend lives a couple km's from his friend , my buddy gets pretty subpar propagation at his house while his friend a couple km's away is already having qso's with op's on the east coast ( we all live in the Pac NW ) . They basically run the same equipment as well . Is it D absorption floating around certain areas and they dont move and thats the way it is ? I have similar experiences where I live ( I'm 300 km east of my friend ) , I hear a friend 20 km south of me getting into locations I can never get into at the same time as him . So , what controls these areas in such a tight space ( like km's away ) ? Cheers Jeff VE7GMX BC Canada Link to comment Share on other sites More sharing options...
3gMike Posted February 21, 2022 Share Posted February 21, 2022 What frequency bands do you all operate on? 1 Link to comment Share on other sites More sharing options...
Jeff Posted February 21, 2022 Author Share Posted February 21, 2022 4 hours ago, 3gMike said: What frequency bands do you all operate on? What I'm describing mostly occurs on 10 meters but have also noted this on 20 meters as well . Link to comment Share on other sites More sharing options...
3gMike Posted February 21, 2022 Share Posted February 21, 2022 (edited) I'm more than a little rusty on the theory of RF propagation, since I trained as a telecommunications technician in the early '70s, and have worked in other fields of electronics in the intervening period, so please forgive me if my questions/ comments miss the point. Since you refer to D absorption I assume that you are referring to daytime transmission, but of course that needs clarification given the signal path length. Presumably if only one end of the link is in daylight you theoretically have better propagation than when both are in daylight, and better again if both ends are in darkness ? But your original question is considering differences in propagation in your immediate locality, so you are suggesting local non-homogeneity in the D layer as a possible cause. It seems reasonable to ask if this effect is present at all times, or is it just that your near-neighbour makes contacts a little sooner than you? Wouldn't you expect the 10m band to perform better than the 20m band? Edit: And is the effect seasonal in any way? Edited February 21, 2022 by 3gMike Additional question 2 Link to comment Share on other sites More sharing options...
helios Posted February 21, 2022 Share Posted February 21, 2022 (edited) 2 km distance shouldn't make a difference on shortwave propagation, except if one of the operators lives next to high mountains, which block low angle radiation. On the 10m band Sporadic-E propagation plays a major role, which is a bit unpredictable and can be very local. But even during sporadic-E I don't notice a significant difference within a 50 km radius. I assume you know the tools to use for empirical propagation measurements. Otherwise I could write a book about that too 😁 If there is a significant difference within 2 km distance, I would assume it is only because of a difference in antennas and/or local noise floor. Edited February 21, 2022 by helios 3 Link to comment Share on other sites More sharing options...
Drax Spacex Posted February 21, 2022 Share Posted February 21, 2022 On 2/20/2022 at 4:50 PM, Jeff said: I do not understand how one area can be so radically different than one thats 2 kilometers away ! Is it that selective that this is an actual thing ? Local noise sources from man-made RF is the most likely reason for high noise and consequently low signal-to-noise ratio at some locations. It could be within your own house - noisy switching power supplies or TV. A frequently-cited external culprit are plant growing lamps. They can produce high levels of broadband noise from several blocks away. 3 Link to comment Share on other sites More sharing options...
Jeff Posted February 22, 2022 Author Share Posted February 22, 2022 Appreciate all the replies . My friend has better antennas then the person who gets the better reception , they both have about nothing for noise . We've discussed the mountains before , many times and he figures thats the cause of all this . Last night we were discussing this and I asked what angle is propagation coming back down at ? If its say 15 degrees , then I could surely see the mountains as an issue , but if the angle is say 60 degrees that probably wouldnt be the reason . 15 would be low enough for his mountains to knock off waves of propagation ? One person asked about night time skip , we only work daytime stuff so this all relates to daylight propagation . Jeff Link to comment Share on other sites More sharing options...
Drax Spacex Posted February 22, 2022 Share Posted February 22, 2022 You could compare the S-meter values at each station for the same time, frequency, and receiver settings (mode, bandwidth, AGC, filters, etc.). This would provide a basis for comparing the overall strength of the S+N being received by each station. Antenna gain, antenna direction, antenna height above ground, antenna polarization (vertical, horizontal, or elliptical), and how well each antenna is tuned for a given operating frequency (low SWR desired) could also account for the differences. 3 Link to comment Share on other sites More sharing options...
hamateur 1953 Posted February 23, 2022 Share Posted February 23, 2022 I have observed this phenomenon as well particularly on 10 meters. Its been quite awhile and to be perfectly candid we couldn’t figure out why. our stations nearly identical etc. You are not alone in your observation of anomalies that seem to make little sense. This was more pronounced during es vs f two for certain, If this helps. mike N7ORL. 73 Link to comment Share on other sites More sharing options...
hamateur 1953 Posted February 23, 2022 Share Posted February 23, 2022 Jeff, since you mentioned night skip. You might really appreciate ten meters during the summer there are patches of e layer ionization that are easily overlooked and the band can be dead quiet because ten isn’t supposed to be open at night, right?? At times it follows an intense auroral display and ssb signals will jump out of nowhere. However we have had other incidents where propagation should not have been possible yet both of us worked three canadian provinces at 3 am pdt!!! no aurora and near solar minimum too!! If you get qst magazine check out pg 65 jan 2022 for more information on the ionosphere than i’ve seen in decades. cu. 73. mike N7ORL 1 Link to comment Share on other sites More sharing options...
helios Posted February 23, 2022 Share Posted February 23, 2022 @JeffWhat antennas are used at both stations? What's the noise floor? (S-level or better dBm/Hz) A "bad" antenna can be better than a "good" antenna, if the good antenna is pointing in the wrong direction ... I have mountains up to 40° elevation, which have a significant effect. 1 Link to comment Share on other sites More sharing options...
Jeff Posted February 24, 2022 Author Share Posted February 24, 2022 18 hours ago, hamateur 1953 said: Jeff, since you mentioned night skip. You might really appreciate ten meters during the summer there are patches of e layer ionization that are easily overlooked and the band can be dead quiet because ten isn’t supposed to be open at night, right?? At times it follows an intense auroral display and ssb signals will jump out of nowhere. However we have had other incidents where propagation should not have been possible yet both of us worked three canadian provinces at 3 am pdt!!! no aurora and near solar minimum too!! If you get qst magazine check out pg 65 jan 2022 for more information on the ionosphere than i’ve seen in decades. cu. 73. mike N7ORL I will be paying close attn to 10 this summer . I'm setup quite well for that band now . 18 hours ago, helios said: @JeffWhat antennas are used at both stations? What's the noise floor? (S-level or better dBm/Hz) A "bad" antenna can be better than a "good" antenna, if the good antenna is pointing in the wrong direction ... I have mountains up to 40° elevation, which have a significant effect. One uses a Delta loop and the other is using a vertical . The delta loop guy is the one having the poorer reception issues. The guys are about 2 or 3 km apart . I'm beginning to believe its the mountains too . Link to comment Share on other sites More sharing options...
3gMike Posted February 24, 2022 Share Posted February 24, 2022 1 hour ago, Jeff said: One uses a Delta loop and the other is using a vertical . The delta loop guy is the one having the poorer reception issues. The guys are about 2 or 3 km apart . I'm beginning to believe its the mountains too . I found this article on choice of antenna, which you may find interesting https://www.eham.net/article/23758 1 Link to comment Share on other sites More sharing options...
JayM Posted July 22, 2022 Share Posted July 22, 2022 (edited) They say vertical HF antennas radiate equally poorly in all directions. Loop antennas are directional with nulls on the broad sides of the antenna, i.e. when facing the triangle. Comparing the two is kind of like comparing apples to oranges, so your two stations aren't at all nearly identical. Now that solar cycle 25 is waxing, do you two experience the same differences which you're attributing to propagation? Edited July 22, 2022 by JayM Added a question for the OP 1 Link to comment Share on other sites More sharing options...
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