From tractorb at ihug.co.nz Sat Aug 16 06:22:35 2014 From: tractorb at ihug.co.nz (Dave Brown) Date: Sat, 16 Aug 2014 22:22:35 +1200 Subject: [Microwave] Before the Friis equation Message-ID: <159AC5BA6A9B47FEB6EAC853BBFB4448@athlon3200> Any historians out there? I'm currently looking into some experimental work that was carried out in the 1930s involving long VHF radio paths. Those involved were amateurs but also recent university graduates. It seems that back then, little if anything, was known about calculating free space path loss. This is hardly surprising as most research at that time was based round propagation from VLF up to HF. Any work at higher frequencies was purely experimental with few, if any, practical applications in mind for the frequencies beyond 30 MHz. The Friis equation, published just after WW2 in Proc IRE for May 1946 (pdf here) http://dsc.ufcg.edu.br/~maspohn/adhoc-grad/papers/Friis%20transmission%20equation/01697062.pdf appears to have been the first time that straight forward calculation of free space path loss was brought to the attention of the scientific and engineering community. The early (1930s) texts I've looked at so far fail to mention anything beyond use of what appear to be mainly empirical relationships for estimating field strength at a distance, which was a prime consideration for LF/MF broadcasting. HF communications was then in its infancy and the effect of the ionosphere was barely understood and yet to have a well developed theoretical basis established. I'd like to establish whether or not any published work exists that predates the Friis article in dealing with the calculation of free space path loss or the related concept of the ratio of received and transmitted powers, including the effects of antennas, over the theoretical free space path. Friis, in his 1946 article, notes that his equation has been in use for some years -" Almost seven years of intensive use" - but makes no mention of the concept having been published earlier. This suggests strongly that WW2 (and probably radar related research) provided the impetus to provide a sound theoretical basis for this type of calculation, but if anyone can provide any references to earlier relevant published work for me I would be most grateful. 73 Dave ZL3FJ From geraldj at netins.net Sat Aug 16 08:14:00 2014 From: geraldj at netins.net (Dr. Gerald N. Johnson) Date: Sat, 16 Aug 2014 06:14:00 -0600 Subject: [Microwave] Before the Friis equation In-Reply-To: <159AC5BA6A9B47FEB6EAC853BBFB4448@athlon3200> References: <159AC5BA6A9B47FEB6EAC853BBFB4448@athlon3200> Message-ID: <53EF4B08.3020805@netins.net> Friis was probably involved at MIT or Harvard during WW2. There is some discussion of the radar equation (propagation loss plus reflection loss) in Volume 1, Radar System Engineering, pages 18 to 21. Then volume 13 is on Propagation of Short Radio Waves. By short they meant shorter than a meter or a quarter meter. I don't have time this morning to read in either much, but these were published '47 and '48 but represent the best work of the World War II years. The two volume set from Harvard from the same era is called. "Very High Frequency Techniques." And I'm sure has a chapter on propagation. These being both reports of fundamental theoretical and experimental research do include many references to older work. MIT Rad Lab volumes are available free on line, Very High Frequency Techniques may be harder to find. 73, Jerry, K0CQ On 8/16/2014 4:22 AM, Dave Brown wrote: > > Any historians out there? > I'm currently looking into some experimental work that was carried out > in the 1930s involving long VHF radio paths. Those involved were > amateurs but also recent university graduates. It seems that back then, > little if anything, was known about calculating free space path loss. > This is hardly surprising as most research at that time was based round > propagation from VLF up to HF. Any work at higher frequencies was purely > experimental with few, if any, practical applications in mind for the > frequencies beyond 30 MHz. > > The Friis equation, published just after WW2 in Proc IRE for May 1946 > (pdf here) > http://dsc.ufcg.edu.br/~maspohn/adhoc-grad/papers/Friis%20transmission%20equation/01697062.pdf > > appears to have been the first time that straight forward calculation of > free space path loss was brought to the attention of the scientific and > engineering community. > > The early (1930s) texts I've looked at so far fail to mention anything > beyond use of what appear to be mainly empirical relationships for > estimating field strength at a distance, which was a prime consideration > for LF/MF broadcasting. HF communications was then in its infancy and > the effect of the ionosphere was barely understood and yet to have a > well developed theoretical basis established. > > I'd like to establish whether or not any published work exists that > predates the Friis article in dealing with the calculation of free space > path loss or the related concept of the ratio of received and > transmitted powers, including the effects of antennas, over the > theoretical free space path. > > Friis, in his 1946 article, notes that his equation has been in use for > some years -" Almost seven years of intensive use" - but makes no > mention of the concept having been published earlier. This suggests > strongly that WW2 (and probably radar related research) provided the > impetus to provide a sound theoretical basis for this type of > calculation, but if anyone can provide any references to earlier > relevant published work for me I would be most grateful. > > 73 > Dave > ZL3FJ > ______________________________________________________________ > Microwave mailing list > Home: http://mailman.qth.net/mailman/listinfo/microwave > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Microwave at mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > From scott at nx7u.net Sat Aug 16 13:58:39 2014 From: scott at nx7u.net (scott at nx7u.net) Date: Sat, 16 Aug 2014 12:58:39 -0500 Subject: [Microwave] Before the Friis equation In-Reply-To: <159AC5BA6A9B47FEB6EAC853BBFB4448@athlon3200> References: <159AC5BA6A9B47FEB6EAC853BBFB4448@athlon3200> Message-ID: May have been too new to make it to textbook. Are these along the lines of what you're looking for? K. A. Norton, "The Calculation of Ground-Wave Field Intensities over a Finitely Conducting Spherical Earth", Proc IRE v29 p623 Dec 1941 Burrows and Gray, "The Effect of the Earth's Curvature on Ground-Wave Propagation", Proc IRE v29, p16, Jan 1941 Eckersley, "Ultra-short-wave Refraction and Diffraction", Jour IEE, v80, p286, Mar 1937 K. A. Norton, "The Propagation of Radio Waves over a Plane Earth", Nature, v125, p954, June 1935 ...and if not these articles, then their citations may be useful. Terman's "Radio Engineers Handbook" has some of the 1930's developments in Section 10. It appears to me that the initial formulation of the problem was to consider the "ground-wave", which is the combination of a direct ray (what we'd call Free Space today) and a ground reflected ray. Then consideration was given of antennas high enough above the surface of the earth that the "ground reflected ray" was negligible compared to the direct ray. And as such, the study of propagation was not uncoupled from the study of antennas. I looked in Kerr, "Propagation of Short Radio Waves", MIT Rad. Lab. but it's mostly meteorological. Perhaps Silver's MIT Rad. Lab. on Antennas has some early citations of the problem. My copy is in storage. On 2014-08-16 05:22, Dave Brown wrote: > Any historians out there? > I'm currently looking into some experimental work that was carried out > in the 1930s involving long VHF radio paths. Those involved were > amateurs but also recent university graduates. It seems that back > then, little if anything, was known about calculating free space path > loss. This is hardly surprising as most research at that time was > based round propagation from VLF up to HF. Any work at higher > frequencies was purely experimental with few, if any, practical > applications in mind for the frequencies beyond 30 MHz. > > The Friis equation, published just after WW2 in Proc IRE for May 1946 > (pdf here) > http://dsc.ufcg.edu.br/~maspohn/adhoc-grad/papers/Friis%20transmission%20equation/01697062.pdf > appears to have been the first time that straight forward calculation > of free space path loss was brought to the attention of the scientific > and engineering community. > > The early (1930s) texts I've looked at so far fail to mention anything > beyond use of what appear to be mainly empirical relationships for > estimating field strength at a distance, which was a prime > consideration for LF/MF broadcasting. HF communications was then in > its infancy and the effect of the ionosphere was barely understood and > yet to have a well developed theoretical basis established. > > I'd like to establish whether or not any published work exists that > predates the Friis article in dealing with the calculation of free > space path loss or the related concept of the ratio of received and > transmitted powers, including the effects of antennas, over the > theoretical free space path. > > Friis, in his 1946 article, notes that his equation has been in use > for some years -" Almost seven years of intensive use" - but makes no > mention of the concept having been published earlier. This suggests > strongly that WW2 (and probably radar related research) provided the > impetus to provide a sound theoretical basis for this type of > calculation, but if anyone can provide any references to earlier > relevant published work for me I would be most grateful. > > 73 > Dave > ZL3FJ > > ______________________________________________________________ > Microwave mailing list > Home: http://mailman.qth.net/mailman/listinfo/microwave > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Microwave at mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html From tractorb at ihug.co.nz Sun Aug 17 18:07:50 2014 From: tractorb at ihug.co.nz (Dave Brown) Date: Mon, 18 Aug 2014 10:07:50 +1200 Subject: [Microwave] Before the Friis equation References: <159AC5BA6A9B47FEB6EAC853BBFB4448@athlon3200> Message-ID: <13A93B93D04F497AB9D71908F6EADD35@athlon3200> Thanks for the suggestions guys- Jerry, I have done a brief search in Rad Lab Vol 1 but need to check it out in more detail. Vol 13 I have not searched, so thats on the to do list now. Scott mentiond Silver- Hadn't got to Silver yet but will look there as well. I may have one of the volumes of VHF Techniques-name sounds familiar- need to dig in the 'library'.(misc boxes and double depth stacked bookshelves!) Else will try the local Engineering Library where they are used to my odd requests by now, I think! Tks for those refs, Scott- a couple sound familiar but will check again. Terman "Radio Engineers Handbook' was first published in early WW2 I think- I didn't find anything specific in there but it did note the inverse square relationship, IIRC. His 'Radio Engineering' from 1932 and 1937 does not have anything specific either. I'm in agreement as to your summary of the development of this issue- my main interest is in establishing whether pre-Friis(1946) the concept he so elegantly summarised was actually fully understood and documented anywhere. 73 Dave ZL3FJ ----- Original Message ----- From: To: Sent: Sunday, August 17, 2014 5:58 AM Subject: Re: [Microwave] Before the Friis equation > May have been too new to make it to textbook. > Are these along the lines of what you're looking for? > > K. A. Norton, "The Calculation of Ground-Wave Field Intensities over a > Finitely Conducting Spherical Earth", Proc IRE v29 p623 Dec 1941 > Burrows and Gray, "The Effect of the Earth's Curvature on Ground-Wave > Propagation", Proc IRE v29, p16, Jan 1941 > Eckersley, "Ultra-short-wave Refraction and Diffraction", Jour IEE, v80, > p286, Mar 1937 > K. A. Norton, "The Propagation of Radio Waves over a Plane Earth", Nature, > v125, p954, June 1935 > ...and if not these articles, then their citations may be useful. > > Terman's "Radio Engineers Handbook" has some of the 1930's developments in > Section 10. > > It appears to me that the initial formulation of the problem was to > consider the "ground-wave", which is the combination of a direct ray (what > we'd call Free Space today) and a ground reflected ray. Then > consideration was given of antennas high enough above the surface of the > earth that the "ground reflected ray" was negligible compared to the > direct ray. And as such, the study of propagation was not uncoupled from > the study of antennas. > > I looked in Kerr, "Propagation of Short Radio Waves", MIT Rad. Lab. but > it's mostly meteorological. > Perhaps Silver's MIT Rad. Lab. on Antennas has some early citations of the > problem. My copy is in storage. > > On 2014-08-16 05:22, Dave Brown wrote: >> Any historians out there? >> I'm currently looking into some experimental work that was carried out >> in the 1930s involving long VHF radio paths. Those involved were >> amateurs but also recent university graduates. It seems that back >> then, little if anything, was known about calculating free space path >> loss. This is hardly surprising as most research at that time was >> based round propagation from VLF up to HF. Any work at higher >> frequencies was purely experimental with few, if any, practical >> applications in mind for the frequencies beyond 30 MHz. >> >> The Friis equation, published just after WW2 in Proc IRE for May 1946 >> (pdf here) >> http://dsc.ufcg.edu.br/~maspohn/adhoc-grad/papers/Friis%20transmission%20equation/01697062.pdf >> appears to have been the first time that straight forward calculation >> of free space path loss was brought to the attention of the scientific >> and engineering community. >> >> The early (1930s) texts I've looked at so far fail to mention anything >> beyond use of what appear to be mainly empirical relationships for >> estimating field strength at a distance, which was a prime >> consideration for LF/MF broadcasting. HF communications was then in >> its infancy and the effect of the ionosphere was barely understood and >> yet to have a well developed theoretical basis established. >> >> I'd like to establish whether or not any published work exists that >> predates the Friis article in dealing with the calculation of free >> space path loss or the related concept of the ratio of received and >> transmitted powers, including the effects of antennas, over the >> theoretical free space path. >> >> Friis, in his 1946 article, notes that his equation has been in use >> for some years -" Almost seven years of intensive use" - but makes no >> mention of the concept having been published earlier. This suggests >> strongly that WW2 (and probably radar related research) provided the >> impetus to provide a sound theoretical basis for this type of >> calculation, but if anyone can provide any references to earlier >> relevant published work for me I would be most grateful. >> >> 73 >> Dave >> ZL3FJ >> >> ______________________________________________________________ >> Microwave mailing list >> Home: http://mailman.qth.net/mailman/listinfo/microwave >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Microwave at mailman.qth.net >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ > Microwave mailing list > Home: http://mailman.qth.net/mailman/listinfo/microwave > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Microwave at mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html From microwave at mailman.qth.net Mon Aug 4 11:50:42 2014 From: microwave at mailman.qth.net (Walter Treftz via Microwave) Date: Mon, 4 Aug 2014 08:50:42 -0700 Subject: [Microwave] FS: HP-5328A Counters Parts Message-ID: <1407167442.98846.YahooMailNeo@web125602.mail.ne1.yahoo.com> Two (2) HP-5328A freq counters from an estate. One totally dead (yeah, checked the fuse) and the other pilot light comes on but nothing else. Unmodified and complete. $15 cash or $25 for both plus shipping from central Florida. 73 Walt (N4GL) (352) 637-1755