<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body><div>Hi Scott,</div><div><br></div><div>You correctly state that the ionosphere plus the earth's magnetic field split any wave enterig the ionsphere in a left-hand and a right-hand circularly polarized component. </div><div><br></div><div>The advantage of a circularly pola about, but the fading reduction, especially in NVIS propagation.</div><div>There most of the fading is caused by interference of the left-hand and right-hand circularly polarized waves, with minima of -35 dB. They will virually disappear when using circular polarization.</div><div><br></div><div>You can find several scientific publication on this subject on my ResearchGate website (Ben Witvliet). </div><div><br></div><div>73, Ben PE5B</div><div><br></div><div><br></div><div><br></div><div id="composer_signature"><div style="font-size:85%;color:#575757" dir="auto">Sent from my Samsung Galaxy smartphone.</div></div><div><br></div><div style="font-size:100%;color:#000000"><!-- originalMessage --><div>-------- Original message --------</div><div>From: hpsdr-request@lists.openhpsdr.org </div><div>Date: 14/06/2019 22:36 (GMT+01:00) </div><div>To: hpsdr@lists.openhpsdr.org </div><div>Subject: Hpsdr Digest, Vol 160, Issue 5 </div><div><br></div></div>Send Hpsdr mailing list submissions to<br> hpsdr@lists.openhpsdr.org<br><br>To subscribe or unsubscribe via the World Wide Web, visit<br> http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org<br>or, via email, send a message with subject or body 'help' to<br> hpsdr-request@lists.openhpsdr.org<br><br>You can reach the person managing the list at<br> hpsdr-owner@lists.openhpsdr.org<br><br>When replying, please edit your Subject line so it is more specific<br>than "Re: Contents of Hpsdr digest..."<br><br><br>PLEASE change your subject line in any replies to this digest to reflect the actual subject!!! Also please trim quotes of previous messages to a minimum necessary to maintain context. Remember: if you post using fancy rtf or html, it will not be read by Digest recipients without a big effort. We all thank you for this thoughtfullness.<br><br>Today's Topics:<br><br> 1. Scientific publication using HPSDR published (Erik van Maanen)<br> 2. Re: Scientific publication using HPSDR published (Scott Traurig)<br><br><br>----------------------------------------------------------------------<br><br>Message: 1<br>Date: Fri, 14 Jun 2019 13:36:39 +0200<br>From: Erik van Maanen <pa3des@xs4all.nl><br>To: hpsdr@lists.openhpsdr.org<br>Subject: [hpsdr] Scientific publication using HPSDR published<br>Message-ID: <240e86e1-1d94-4584-26ae-b70d06c25f94@xs4all.nl><br>Content-Type: text/plain; charset=utf-8; format=flowed<br><br>Dear all,<br><br><br>Our scientific publication on NVIS research is just published in MDPI <br>Sensors journal.<br>We used a measurement system based on the ANAN200D and powersdr as well <br>as a large amount of self developed hard and software.<br>We specially like to thank Joe K5SO and Doug W5WC for their support and <br>modifications of powersdr.<br>(These modifications are now part of the normal powersdr release.)<br><br>The publication is Open Source, freely downloadable for anyone, and can <br>be found on:<br>https://www.mdpi.com/1424-8220/19/11/2616<br>Besides good reading material for the weekend we also hope it can be <br>used as another example of the value of ham radio.<br><br><br>73' Erik PA3DES and Ben PA5B<br><br><br>------------------------------<br><br>Message: 2<br>Date: Fri, 14 Jun 2019 16:29:11 -0400<br>From: Scott Traurig <scott.traurig@gmail.com><br>To: hpsdr <hpsdr@lists.openhpsdr.org><br>Subject: Re: [hpsdr] Scientific publication using HPSDR published<br>Message-ID:<br> <CAGK9zXpZQFvtH97ioTC53_XMWK6GeAVDOBnQ2vDx=OeB+pDNpw@mail.gmail.com><br>Content-Type: text/plain; charset="utf-8"<br><br>It's probably worth mentioning that if you build an HF turnstile antenna<br>(two crossed dipoles or inverted V's) there are no modifications required<br>to PowerSDR or Thetis to use them as a circularly polarized array on<br>receive. Just feed each dipole to RX1 (ADC0) and RX2 (ADC1) with equal<br>length coaxial cable of the same type. Then use the "Diversity" function to<br>invoke a positive or negative 90 degree phase difference with unity gain.<br>You'll get either left or right hand circular polarization. I've always<br>wanted to try this, but I do not have a way to put up the required antennas.<br><br>Of course you'll have to choose one antenna or the other for transmit. Or<br>you could build a 90 degree phasing harness and do it the old school way<br>but the phasing harness will only be correct at a single frequency.<br><br>This applies to more than just NVIS. All signals reflected off of the<br>ionosphere become circularly polarized. If you can match your polarization<br>you can avoid the polarization loss from circular to linear. However at<br>worst that is only 3dB in theory.<br><br>73,<br><br>Scott<br><br>On Fri, Jun 14, 2019 at 7:36 AM Erik van Maanen <pa3des@xs4all.nl> wrote:<br><br>> Our scientific publication on NVIS research is just published in MDPI<br>> Sensors journal.<br>> We used a measurement system based on the ANAN200D and powersdr as well<br>> as a large amount of self developed hard and software.<br>> We specially like to thank Joe K5SO and Doug W5WC for their support and<br>> modifications of powersdr.<br>> (These modifications are now part of the normal powersdr release.)<br>><br>> The publication is Open Source, freely downloadable for anyone, and can<br>> be found on:<br>> https://www.mdpi.com/1424-8220/19/11/2616<br>> Besides good reading material for the weekend we also hope it can be<br>> used as another example of the value of ham radio.<br>><br>> 73' Erik PA3DES and Ben PA5B<br>><br>><br>-------------- next part --------------<br>An HTML attachment was scrubbed...<br>URL: <http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/attachments/20190614/7809a2e1/attachment-0001.html><br><br>------------------------------<br><br>Subject: Digest Footer<br><br>_______________________________________________<br>HPSDR Discussion List<br>To post msg: hpsdr@openhpsdr.org<br>Subscription help: http://lists.openhpsdr.org/listinfo.cgi/hpsdr-openhpsdr.org<br>HPSDR web page: http://openhpsdr.org<br>Archives: http://lists.openhpsdr.org/pipermail/hpsdr-openhpsdr.org/<br><br>------------------------------<br><br>End of Hpsdr Digest, Vol 160, Issue 5<br>*************************************<br></body></html>