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Aurora Dx Communication High in the North

Volker Grassmann, DF5AI

Febuary 17, 2003

Introduction

Jussi, OH5LK, is sceptical about Auroral backscatter predictions in the far north, see the below email. I have very much respect for our colleagues from Scandinavia because the Aurora is an everyday experience high in the north. Thus, if a fellow ham from Finland tells you there is perhaps something wrong with all this Aurora predictions, you better go and check your routines again. This is what I did...

Jussi's email from Febuary 10, 2003:

Dear Volker! I read your article in DUBUS with much interest. I think there is some kind of a basic fault in all predictions on how the Aurora situation is very high in the north.

On a normal (weak) aurora (on which I do not hear any DX stations at all, for example no OZ/DL stations), I can work stations up to the arctic circle on Aurora. For example SM2CEW or even stations that are one square north of him (for example OH9 stations in Rovaniemi, KP26VM). According to the theory I guess it should not be possible at all to work Aurora up that high in the north. I have also worked on Aurora UA1ZCL from KP78TX and the northernmost station I have ever worked on 144 MHz aurora has been UA1ZCG in KP59JK. And I am now talking about normal aurora tone signals, not about Auroral-E.

...

KP30ONFAIAurora dx range from the KP30 grid square

Using the BeamFinder analysis software [1], the dx range in Aurora communication was calculated as a function of the aspect angle. The figure shows the results for the KP30 grid square, i.e. Jussi's home location.

The yellow area displays the dx range at an aspect angle of 90 degree which corresponds to the ideal geometry in Auroral backscatter (see e.g. [2]). However, in the so-called unusual Aurora QSOs [2] the aspect angle is smaller and the corresponding dx range is longer. The green and blue area displays the results for 85 and 80 degree, respectively. Note that the aspect angle was 77.5 degree in [2] and 70 degree in [3], i.e. we might say the figure displays the dx range on the edge between ordinary and unusal Aurora QSOs.

Analysing Jussi's dx observation

Dx QSOs to the Polar circle, SM2 and Rovaniemi correspond to an aspect angle between 90 and 85 degree, see the map. Thus, it is no surprise that this type of QSO is available even in minor openings.

Jussi's QSO with UA1ZCL (KP78) is just inside the blue area, the UA1ZCG QSO (KP59) however exceeds that area. In the later case we may estimate an aspect angle between 80 and 75 degree similiar to unusual Aurora QSOs observed by others.

Conclusions

There is currently no evidence that Jussi's observations cannot be explained within the theoretical framework implemented in the BeamFinder software. I am grateful to Jussi for providing this very interesting details from to far north of Scandinavia. It is indeed very important to test the software as much as possible by analysing real examples in Aurora dx communication.

Thanks for the email, Jussi.

References

[1]

BeamFinder Analysis Software

Grassmann, V., DF5AI, http://www.df5ai.net/BeamFinder/bfintro.html

[2]

Unusual Aurora Observations in the 144 MHz Band

Grassmann, V., DF5AI, Dubus 4, p. 39-41, 2002

see also: http://www.df5ai.net/ArticlesDL/ONScatter/ONScatter.html

[3]

Unusual Aurora QSO Between DK3UZ and UA1ZCL

Grassmann, V., DF5AI, http://www.df5ai.net/ArticlesDL/DK3UZ-UA1ZCL/dk3uz_ua1zcl.html

From: http://www.df5ai.net

Copyright (C) of Volker Grassmann. All rights reserved. The material, or parts thereof, may not be reproduced in any form without prior written permission of the author.