At his request and on his behalf, I am posting an article by my friend Dr. Ulrich Rohde entitled "Electrically Short Antennas". The co-authors for this article are Magdalena Salazar-Palma and Tapan K. Sarkar. 73, Adam VA7OJ/AB4OJ
As the Dr. seems to be a lifelong member of this site, why did he not post this himself? I smell something fishy here.....
The fishy part is that goofed to load it up with a introduction picture so I asked for help rather then make a mistake. Is this considered disorderly conduct ? I hop that explains it. 73 de Ulrich, N1UL
Thanks, Good stuff as always. I like QRZ for this and not for "look at me videos" At some point were going to really miss having true Elmers here.
No apology will be offered considering the amount of effort hackers go to obtaining our information it makes good sense to be suspicious and let's face it, a paper that says its created by a member but posted by another is certainly suspicious. Maybe the better option was to assist the author with posting it under his own identification? All users should be very careful in downloading or opening files (yes including .pdf formated documents] as they may contain malware and other unwanted items.
Thanks and likewise happy holidays, here is a screenshot from a monitoring receiver Pretty good up to 21 MHz, RX 2 MHz to 22 MHz display using an active antenna; 73 de Ulrich N1UL
A very interesting paper and presentation. It highlights the difficult design considerations which especially designers of co-located systems on small platforms face. Former associate Emelie Agnedal wrote a paper "System requirements for co-located equipment on small platforms and cost-effective measures to reduce interference" which was presented at the Nordic HF Conference in 2o13 where many of the questions were addressed. Finally, recall these almost 45 year old spectrum plots? There certainly is a profound difference in HF spectrum occupancy levels between now and "yesteryear". 73/ Karl-Arne SM0AOM
Good morning from the USA, I remember this paper very well. This was measured in the USA and it’s equivalent in Europe was about 15 to 20 dB louder, European Broadcast Stations and “Propaganda “ stations including the Voice of America. Most ham radio stations (RX) on 7 MHz in Europe were totally overloaded and I introduced the PIN diode Attenuator and replaced the Si switching diodes. To a degree i am afraid that when the sun wakes up again, the A/D converters of the SDRs will be totally overwhelmed without an adaptive PIN diode based attenuator and it’s AGC system. This complex system will not be trivial and expensive. My active antenna saw already 60 dBuV around 9 MHz. European broadcast stations. There is more to a good receiver then selectivity and sensitivity! 73 de Ulrich
