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An interesting point is being made here concerning the differences between line of sight and sky wave DX propagation. While it is an established fact that a full length linear radiator produces the most field strength on the horizon, I won't be so quick to 100% rule out other possibilities for DX work. Changing polarization and different radiation elevation angles play a significant role in DX. I am reluctant to admit this because I have not done any controlled scientific tests in the area however, I too have seen signs of improved DX performance from some loaded antennas that were still relatively close to 1/4 wavelength physically or from 1/4 waves with larger top hats. The possible advantage only appears in DX and shows slightly less gain on the distant horizon.

It's difficult to determine any small advantages these antennas could have in DX since signals are never stable enough to make a controlled comparison. Instead we are left to make relative generalizations like "I seem to be getting better results with this antenna over another one in DX". I can only theorize why this may be the case. It is my opinion that it has nothing to do with gain since it will be reduced and everything to do with radiation angles. Any horizontal radiation surface including a top hat to some degree, will have entirely different radiation angles then the vertical component since radiation occurs around the conductor. In the case of helically wound coils, they do not produce radiation that is perfectly broadside to their physical orientation. The field can be intense at angles off the ends of the coil. These radiation components may also be reflecting differently off your vehicles groundplane then a straight vertical would.

<blockquote data-quote="Shockwave" data-source="post: 275843" data-attributes="member: 10882">An interesting point is being made here concerning the differences between line of sight and sky wave DX propagation. While it is an established fact that a full length linear radiator produces the most field strength on the horizon, I won&#039;t be so quick to 100% rule out other possibilities for DX work. Changing polarization and different radiation elevation angles play a significant role in DX. I am reluctant to admit this because I have not done any controlled scientific tests in the area however, I too have seen signs of improved DX performance from some loaded antennas that were still relatively close to 1/4 wavelength physically or from 1/4 waves with larger top hats. The possible advantage only appears in DX and shows slightly less gain on the distant horizon.It&#039;s difficult to determine any small advantages these antennas could have in DX since signals are never stable enough to make a controlled comparison. Instead we are left to make relative generalizations like &quot;I seem to be getting better results with this antenna over another one in DX&quot;. I can only theorize why this may be the case. It is my opinion that it has nothing to do with gain since it will be reduced and everything to do with radiation angles. Any horizontal radiation surface including a top hat to some degree, will have entirely different radiation angles then the vertical component since radiation occurs around the conductor. In the case of helically wound coils, they do not produce radiation that is perfectly broadside to their physical orientation. The field can be intense at angles off the ends of the coil. These radiation components may also be reflecting differently off your vehicles groundplane then a straight vertical would.</blockquote>

[QUOTE="Shockwave, post: 275843, member: 10882"] An interesting point is being made here concerning the differences between line of sight and sky wave DX propagation. While it is an established fact that a full length linear radiator produces the most field strength on the horizon, I won't be so quick to 100% rule out other possibilities for DX work. Changing polarization and different radiation elevation angles play a significant role in DX. I am reluctant to admit this because I have not done any controlled scientific tests in the area however, I too have seen signs of improved DX performance from some loaded antennas that were still relatively close to 1/4 wavelength physically or from 1/4 waves with larger top hats. The possible advantage only appears in DX and shows slightly less gain on the distant horizon. It's difficult to determine any small advantages these antennas could have in DX since signals are never stable enough to make a controlled comparison. Instead we are left to make relative generalizations like "I seem to be getting better results with this antenna over another one in DX". I can only theorize why this may be the case. It is my opinion that it has nothing to do with gain since it will be reduced and everything to do with radiation angles. Any horizontal radiation surface including a top hat to some degree, will have entirely different radiation angles then the vertical component since radiation occurs around the conductor. In the case of helically wound coils, they do not produce radiation that is perfectly broadside to their physical orientation. The field can be intense at angles off the ends of the coil. These radiation components may also be reflecting differently off your vehicles groundplane then a straight vertical would. [/QUOTE]

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