On 9/28/2021 4:51 PM, John Larkin wrote:> On Tue, 28 Sep 2021 16:32:54 -0400, bitrex <user@example.net> wrote: > >> On 9/28/2021 3:30 PM, John Larkin wrote: >>> On Tue, 28 Sep 2021 11:04:15 -0700, John Robertson <spam@flippers.com> >>> wrote: >>> >>>> On 2021/09/28 9:18 a.m., jlarkin@highlandsniptechnology.com wrote: >>>>> Everything that conducts is a lossy transmission line. >>>>> >>>>> A solenoid inductor. >>>>> >>>>> https://www.dropbox.com/s/b5eae1jwsdscw4k/PC_3.jpg?raw=1 >>>>> >>>> ... >>>>> >>>>> >>>> >>>> Do you mind showing your test setup to get that trace? You must have a >>>> back-emf diode on the coil, but that diminishing slope looks wrong... >>> >>> >>> The setup is in the picture. The inductor goes between an SMA >>> connector and ground. The scope trace is 50 ohm TDR. >>> >>> Closeup: >>> >>> https://www.dropbox.com/s/6kzbwo87olh8am3/PC_1.jpg?raw=1 >>> >>> Given a voltage step from a 50 ohm source, one would expect an >>> inductor to have a spike of the applied step voltage, and an >>> exponential decay towards ground with time constant L/50. What's cool >>> is the initial flat, with the winding acting like a transmission line >>> roughly 800 ps round-trip. >>> >>> I think. >>> >> >> If I remember correctly at one time before it was known whether fiber >> optics would be feasible, the telcos were going to use helix microwave >> wave-guides for "broadband" data transmission > > There were trials done using light, in a pipe guided by thermal > gradients. > > I remember when hills had giant sugar-scoop microwave antennas. Now > they have cell towers. If we get gen5 or 6 cellular, all that will be > gone. >Used to be a hill near me with some of that stuff on it as my father told it, all ripped down before my time I guess, but there are still a few former sites standing in New England I think, probably used for cell service now. With respect to the circuit the back-EMF can't show up until it "knows" it's a finite inductor and not some fashion of infinite helical transmission line, 400 ps is ~4.7 inches at the speed of light, how long would the helix be if you stretched it out
txlines
Started by ●September 28, 2021
Reply by ●September 28, 20212021-09-28
Reply by ●September 28, 20212021-09-28
On 2021/09/28 1:51 p.m., John Larkin wrote:> On Tue, 28 Sep 2021 16:32:54 -0400, bitrex <user@example.net> wrote: > >> On 9/28/2021 3:30 PM, John Larkin wrote: >>> On Tue, 28 Sep 2021 11:04:15 -0700, John Robertson <spam@flippers.com> >>> wrote: >>> >>>> On 2021/09/28 9:18 a.m., jlarkin@highlandsniptechnology.com wrote: >>>>> Everything that conducts is a lossy transmission line. >>>>> >>>>> A solenoid inductor. >>>>> >>>>> https://www.dropbox.com/s/b5eae1jwsdscw4k/PC_3.jpg?raw=1 >>>>> >>>> ... >>>>> >>>>> >>>> >>>> Do you mind showing your test setup to get that trace? You must have a >>>> back-emf diode on the coil, but that diminishing slope looks wrong... >>> >>> >>> The setup is in the picture. The inductor goes between an SMA >>> connector and ground. The scope trace is 50 ohm TDR. >>> >>> Closeup: >>> >>> https://www.dropbox.com/s/6kzbwo87olh8am3/PC_1.jpg?raw=1 >>> >>> Given a voltage step from a 50 ohm source, one would expect an >>> inductor to have a spike of the applied step voltage, and an >>> exponential decay towards ground with time constant L/50. What's cool >>> is the initial flat, with the winding acting like a transmission line >>> roughly 800 ps round-trip. >>> >>> I think. >>> >> >> If I remember correctly at one time before it was known whether fiber >> optics would be feasible, the telcos were going to use helix microwave >> wave-guides for "broadband" data transmission > > There were trials done using light, in a pipe guided by thermal > gradients. > > I remember when hills had giant sugar-scoop microwave antennas. Now > they have cell towers. If we get gen5 or 6 cellular, all that will be > gone. >We still have scoops on our telco (Telus) building here in Vancouver at Boundary and Kingsway. There is an obvious missing connection to the building from the bottom of each scoop: https://goo.gl/maps/cYVDeKiqzPu13zGu5 John :-#)#
Reply by ●September 28, 20212021-09-28
On Tue, 28 Sep 2021 17:01:28 -0400, bitrex <user@example.net> wrote:>On 9/28/2021 4:51 PM, John Larkin wrote: >> On Tue, 28 Sep 2021 16:32:54 -0400, bitrex <user@example.net> wrote: >> >>> On 9/28/2021 3:30 PM, John Larkin wrote: >>>> On Tue, 28 Sep 2021 11:04:15 -0700, John Robertson <spam@flippers.com> >>>> wrote: >>>> >>>>> On 2021/09/28 9:18 a.m., jlarkin@highlandsniptechnology.com wrote: >>>>>> Everything that conducts is a lossy transmission line. >>>>>> >>>>>> A solenoid inductor. >>>>>> >>>>>> https://www.dropbox.com/s/b5eae1jwsdscw4k/PC_3.jpg?raw=1 >>>>>> >>>>> ... >>>>>> >>>>>> >>>>> >>>>> Do you mind showing your test setup to get that trace? You must have a >>>>> back-emf diode on the coil, but that diminishing slope looks wrong... >>>> >>>> >>>> The setup is in the picture. The inductor goes between an SMA >>>> connector and ground. The scope trace is 50 ohm TDR. >>>> >>>> Closeup: >>>> >>>> https://www.dropbox.com/s/6kzbwo87olh8am3/PC_1.jpg?raw=1 >>>> >>>> Given a voltage step from a 50 ohm source, one would expect an >>>> inductor to have a spike of the applied step voltage, and an >>>> exponential decay towards ground with time constant L/50. What's cool >>>> is the initial flat, with the winding acting like a transmission line >>>> roughly 800 ps round-trip. >>>> >>>> I think. >>>> >>> >>> If I remember correctly at one time before it was known whether fiber >>> optics would be feasible, the telcos were going to use helix microwave >>> wave-guides for "broadband" data transmission >> >> There were trials done using light, in a pipe guided by thermal >> gradients. >> >> I remember when hills had giant sugar-scoop microwave antennas. Now >> they have cell towers. If we get gen5 or 6 cellular, all that will be >> gone. >> > >Used to be a hill near me with some of that stuff on it as my father >told it, all ripped down before my time I guess, but there are still a >few former sites standing in New England I think, probably used for cell >service now. > >With respect to the circuit the back-EMF can't show up until it "knows" >it's a finite inductor and not some fashion of infinite helical >transmission line, 400 ps is ~4.7 inches at the speed of light, how long >would the helix be if you stretched it outThat inductor is 15 turns of about 0.1" diameter, so the wire length is about 4.7". Good grief, right on! Of course, the dielectric is plastic, so the prop velocity is less than c. And there is coupling between the loops. Yeah, it doesn't realize that it's actually a solenoid inductor until the incident wave makes the round trip. Sort of. -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon
Reply by ●September 28, 20212021-09-28
On Tue, 28 Sep 2021 15:21:42 -0700, John Robertson <spam@flippers.com> wrote:> >On 2021/09/28 1:51 p.m., John Larkin wrote: >> On Tue, 28 Sep 2021 16:32:54 -0400, bitrex <user@example.net> wrote: >> >>> On 9/28/2021 3:30 PM, John Larkin wrote: >>>> On Tue, 28 Sep 2021 11:04:15 -0700, John Robertson <spam@flippers.com> >>>> wrote: >>>> >>>>> On 2021/09/28 9:18 a.m., jlarkin@highlandsniptechnology.com wrote: >>>>>> Everything that conducts is a lossy transmission line. >>>>>> >>>>>> A solenoid inductor. >>>>>> >>>>>> https://www.dropbox.com/s/b5eae1jwsdscw4k/PC_3.jpg?raw=1 >>>>>> >>>>> ... >>>>>> >>>>>> >>>>> >>>>> Do you mind showing your test setup to get that trace? You must have a >>>>> back-emf diode on the coil, but that diminishing slope looks wrong... >>>> >>>> >>>> The setup is in the picture. The inductor goes between an SMA >>>> connector and ground. The scope trace is 50 ohm TDR. >>>> >>>> Closeup: >>>> >>>> https://www.dropbox.com/s/6kzbwo87olh8am3/PC_1.jpg?raw=1 >>>> >>>> Given a voltage step from a 50 ohm source, one would expect an >>>> inductor to have a spike of the applied step voltage, and an >>>> exponential decay towards ground with time constant L/50. What's cool >>>> is the initial flat, with the winding acting like a transmission line >>>> roughly 800 ps round-trip. >>>> >>>> I think. >>>> >>> >>> If I remember correctly at one time before it was known whether fiber >>> optics would be feasible, the telcos were going to use helix microwave >>> wave-guides for "broadband" data transmission >> >> There were trials done using light, in a pipe guided by thermal >> gradients. >> >> I remember when hills had giant sugar-scoop microwave antennas. Now >> they have cell towers. If we get gen5 or 6 cellular, all that will be >> gone. >> > >We still have scoops on our telco (Telus) building here in Vancouver at >Boundary and Kingsway. There is an obvious missing connection to the >building from the bottom of each scoop: > >https://goo.gl/maps/cYVDeKiqzPu13zGu5 > >John :-#)#Some guys at Bell Labs discovered the universe's background radiation with a big scoop antenna. The initial noise figure was unaccountably high until they evicted some pigeons from inside. -- If a man will begin with certainties, he shall end with doubts, but if he will be content to begin with doubts he shall end in certainties. Francis Bacon
Reply by ●September 28, 20212021-09-28
On 29/9/21 2:18 am, jlarkin@highlandsniptechnology.com wrote:> Everything that conducts is a lossy transmission line. > > A solenoid inductor. > > https://www.dropbox.com/s/b5eae1jwsdscw4k/PC_3.jpg?raw=1 > > A series string of surface-mount resistors. > > A ground plane or power pour. > > A wound-foil capacitor. > > A wirewound resistor. > > A piece of wire in free air. > > A via. > > A pcb trace, of course.and everything that conducts is an antenna. A tree, for example. Ask any foxhunter what happens to signals in a forest, depending on the wavelength in use and the relative size of the branches and leaves. 70cm in a pine forest is a real doozy - the signal just vanishes. New definitions: * a conductor is a transmission line to the extent that it constrains the energy to follow it, rather than radiating it * a conductor is an antenna to the extent that it radiates the energy delivered into it These are complementary. Any conductor is both, in varying degree CH
Reply by ●September 28, 20212021-09-28
On Wednesday, September 29, 2021 at 8:58:26 AM UTC+10, John Larkin wrote:> On Tue, 28 Sep 2021 15:21:42 -0700, John Robertson <sp...@flippers.com> wrote: > >On 2021/09/28 1:51 p.m., John Larkin wrote: > >> On Tue, 28 Sep 2021 16:32:54 -0400, bitrex <us...@example.net> wrote: > >>> On 9/28/2021 3:30 PM, John Larkin wrote: > >>>> On Tue, 28 Sep 2021 11:04:15 -0700, John Robertson <sp...@flippers.com> wrote: > >>>>> On 2021/09/28 9:18 a.m., jla...@highlandsniptechnology.com wrote:> Some guys at Bell Labs discovered the universe's background radiation > with a big scoop antenna. The initial noise figure was unaccountably > high until they evicted some pigeons from inside.It wasn't so much the pigeons as their droppings. Rather like some of the posters here. -- Bill Sloman, Sydney
Reply by ●September 29, 20212021-09-29
John Larkin <jlarkin@highland_atwork_technology.com> wrote:> On Tue, 28 Sep 2021 16:32:54 -0400, bitrex <user@example.net> wrote: > >>On 9/28/2021 3:30 PM, John Larkin wrote: >>> On Tue, 28 Sep 2021 11:04:15 -0700, John Robertson <spam@flippers.com> >>> wrote: >>> >>>> On 2021/09/28 9:18 a.m., jlarkin@highlandsniptechnology.com wrote: >>>>> Everything that conducts is a lossy transmission line. >>>>> >>>>> A solenoid inductor. >>>>> >>>>> https://www.dropbox.com/s/b5eae1jwsdscw4k/PC_3.jpg?raw=1 >>>>> >>>> ... >>>>> >>>>> >>>> >>>> Do you mind showing your test setup to get that trace? You must have a >>>> back-emf diode on the coil, but that diminishing slope looks wrong... >>> >>> >>> The setup is in the picture. The inductor goes between an SMA >>> connector and ground. The scope trace is 50 ohm TDR. >>> >>> Closeup: >>> >>> https://www.dropbox.com/s/6kzbwo87olh8am3/PC_1.jpg?raw=1 >>> >>> Given a voltage step from a 50 ohm source, one would expect an >>> inductor to have a spike of the applied step voltage, and an >>> exponential decay towards ground with time constant L/50. What's cool >>> is the initial flat, with the winding acting like a transmission line >>> roughly 800 ps round-trip. >>> >>> I think. >>> >> >>If I remember correctly at one time before it was known whether fiber >>optics would be feasible, the telcos were going to use helix microwave >>wave-guides for "broadband" data transmission > > There were trials done using light, in a pipe guided by thermal > gradients. > > I remember when hills had giant sugar-scoop microwave antennas. Now > they have cell towers. If we get gen5 or 6 cellular, all that will be > gone.microwave links for long distance phone service is dead, but there's still a niche use for even longwave communications links across the US and the atlantic. Radiowaves are faster than light through fiber optics and in the world of high speed trading, faster wins.
Reply by ●September 29, 20212021-09-29
On 2021/09/28 6:17 p.m., Clifford Heath wrote:> On 29/9/21 2:18 am, jlarkin@highlandsniptechnology.com wrote: >> Everything that conducts is a lossy transmission line. >> >> A solenoid inductor. >> >> https://www.dropbox.com/s/b5eae1jwsdscw4k/PC_3.jpg?raw=1 >> >> A series string of surface-mount resistors. >> >> A ground plane or power pour. >> >> A wound-foil capacitor. >> >> A wirewound resistor. >> >> A piece of wire in free air. >> >> A via. >> >> A pcb trace, of course. > > and everything that conducts is an antenna. > > A tree, for example. Ask any foxhunter what happens to signals in a > forest, depending on the wavelength in use and the relative size of the > branches and leaves. 70cm in a pine forest is a real doozy - the signal > just vanishes. > > New definitions: > > * a conductor is a transmission line to the extent that it constrains > the energy to follow it, rather than radiating it > > * a conductor is an antenna to the extent that it radiates the energy > delivered into it > > These are complementary. Any conductor is both, in varying degree > > CHFolks have already figured out that trees communicate through their roots and the fungi in the soil... https://e360.yale.edu/features/exploring_how_and_why_trees_talk_to_each_other now perhaps they should see if they use radio waves? Super long wave, much likes subs use... Interesting fantasy, and may be something in it too. The more we learn the more there is to learn! How anyone can say life is boring is beyond me. John :-#)#
Reply by ●September 29, 20212021-09-29
On 29/09/21 02:17, Clifford Heath wrote:> On 29/9/21 2:18 am, jlarkin@highlandsniptechnology.com wrote: >> Everything that conducts is a lossy transmission line. >> >> A solenoid inductor. >> >> https://www.dropbox.com/s/b5eae1jwsdscw4k/PC_3.jpg?raw=1 >> >> A series string of surface-mount resistors. >> >> A ground plane or power pour. >> >> A wound-foil capacitor. >> >> A wirewound resistor. >> >> A piece of wire in free air. >> >> A via. >> >> A pcb trace, of course. > > and everything that conducts is an antenna. > > A tree, for example. Ask any foxhunter what happens to signals in a forest, > depending on the wavelength in use and the relative size of the branches and > leaves. 70cm in a pine forest is a real doozy - the signal just vanishes.Long ago I remember seeing an Indian report that they could make a cheap antenna for the first TVs there. All they did was insert the coax signal line into a coconut tree near ground level.
Reply by ●September 29, 20212021-09-29
On Tue, 28 Sep 2021 09:18:18 -0700, jlarkin@highlandsniptechnology.com wrote:>Everything that conducts is a lossy transmission line. > >A solenoid inductor. > >https://www.dropbox.com/s/b5eae1jwsdscw4k/PC_3.jpg?raw=1 > >A series string of surface-mount resistors. > >A ground plane or power pour. > >A wound-foil capacitor. > >A wirewound resistor. > >A piece of wire in free air. > >A via. > >A pcb trace, of course.. . . and Ground is everywhere. RL
