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Sci.Electronics.Basics -> Waveguide
There are 13 messages in this thread.
You are currently looking at messages 1 to 13.
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Author: Roger DewhurstDate: 19:26 22-03-07
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I want to feed a single pulse of, let us say, 10 to 100 microseconds
duration, into a short length of waveguide and detect that pulse upto 1000
metres away in another short length of waveguide set to be more or less
co-linear with the first piece of waveguide. Can anyone suggest how I might
implement this?
R
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Author: GarethDate: 07:15 25-03-07
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Roger Dewhurst wrote:
> I want to feed a single pulse of, let us say, 10 to 100 microseconds
> duration, into a short length of waveguide and detect that pulse upto 1000
> metres away in another short length of waveguide set to be more or less
> co-linear with the first piece of waveguide. Can anyone suggest how I might
> implement this?
>
Please can you supply a bit more information, in particular:
What exactly are you trying to do?
Is there a good reason why want to use waveguide?
What is the carrier frequency of this pulse?
Gareth
--
-----------------------------------------------------------------------
To reply to me directly:
Replace privacy.net with: totalise DOT co DOT uk and replace me with
gareth.harris
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Author: John LarkinDate: 14:38 25-03-07
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On Fri, 23 Mar 2007 11:26:05 +1200, "Roger Dewhurst"
<dewhurst@wave.co.nz> wrote:
>I want to feed a single pulse of, let us say, 10 to 100 microseconds
>duration, into a short length of waveguide and detect that pulse upto 1000
>metres away in another short length of waveguide set to be more or less
>co-linear with the first piece of waveguide. Can anyone suggest how I might
>implement this?
>
>R
>
That probably can't be done. No reasonably sized waveguide (smaller
than Central Park, say) will propagate signals that slow.
Why do you want to do this?
John
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Author: Roger DewhurstDate: 15:36 25-03-07
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"Gareth" <me@privacy.net> wrote in message
news:yKadnaqxyN4lxJvbRVnyvQA@brightview.com...
> Roger Dewhurst wrote:
> > I want to feed a single pulse of, let us say, 10 to 100 microseconds
> > duration, into a short length of waveguide and detect that pulse upto
1000
> > metres away in another short length of waveguide set to be more or less
> > co-linear with the first piece of waveguide. Can anyone suggest how I
might
> > implement this?
> >
>
> Please can you supply a bit more information, in particular:
>
> What exactly are you trying to do?
Transfer instantaneously a start signal to some mobile electronic equipment
which is in line of sight upto 1000 metres away.
>
> Is there a good reason why want to use waveguide?
I do not want interference by or to other radio transmissions but other
options are possible. It is just too inconvenient to run a wire except for
the shorter distances. For short distances the start signal by wire is a
momentary low triggering pin 2 on a 555.
>
> What is the carrier frequency of this pulse?
Flexible but around 2 gigahertz. The waveguide can be of any size that is
reasonably portable and aimable and the carrier wave should match it. For
preference it will be just outside any recognized band.
Roger
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Author: Roger DewhurstDate: 15:42 25-03-07
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"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in
message
news:o7gd03lqp006plvbl2mv7ou07c9cr0p5l7@4ax.com...
> On Fri, 23 Mar 2007 11:26:05 +1200, "Roger Dewhurst"
> <dewhurst@wave.co.nz> wrote:
>
> >I want to feed a single pulse of, let us say, 10 to 100 microseconds
> >duration, into a short length of waveguide and detect that pulse upto
1000
> >metres away in another short length of waveguide set to be more or less
> >co-linear with the first piece of waveguide. Can anyone suggest how I
might
> >implement this?
> >
> >R
> >
>
> That probably can't be done. No reasonably sized waveguide (smaller
> than Central Park, say) will propagate signals that slow.
The 'pulse' might be a brief period of carrier wave or even a brief gap in
the carrier wave. Pulse was probably a poor choice of word on my part. It
has to start some other electronic equipment which measues time intervals in
milliseconds (not microseconds!).
>
> Why do you want to do this?
See above.
Roger
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Author: GarethDate: 16:13 25-03-07
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Roger Dewhurst wrote:
> "Gareth" <me@privacy.net> wrote in message
> news:yKadnaqxyN4lxJvbRVnyvQA@brightview.com...
>> Roger Dewhurst wrote:
>>> I want to feed a single pulse of, let us say, 10 to 100 microseconds
>>> duration, into a short length of waveguide and detect that pulse upto
> 1000
>>> metres away in another short length of waveguide set to be more or less
>>> co-linear with the first piece of waveguide. Can anyone suggest how I
> might
>>> implement this?
>>>
>> Please can you supply a bit more information, in particular:
>>
>> What exactly are you trying to do?
>
> Transfer instantaneously a start signal to some mobile electronic equipment
> which is in line of sight upto 1000 metres away.
>
>> Is there a good reason why want to use waveguide?
>
> I do not want interference by or to other radio transmissions but other
> options are possible. It is just too inconvenient to run a wire except for
> the shorter distances. For short distances the start signal by wire is a
> momentary low triggering pin 2 on a 555.
Apologies if I have misunderstood your post, but I don't think waveguide
does what you think it does.
Are you thinking that you can confine your pulse to a narrow beam so
that it can only be picked up by another bit waveguide of 1km away which
is carefully aligned? If that is what you are thinking it doesn't work
like that. a signal from an open ended waveguide will have a beamwidth
of ~60 degrees.
If you want to confine your signal to a narrow beamwidth you need a
large antenna. The beamwidth, in radians, of an antenna is
approximately the wavelength divided by the antenna diameter. at 2 GHz
the wavelength is ~6", so you need a very large antenna if you want a
narrow beamwidth.
--
-----------------------------------------------------------------------
To reply to me directly:
Replace privacy.net with: totalise DOT co DOT uk and replace me with
gareth.harris
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Author: Roger DewhurstDate: 19:04 25-03-07
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Author: John LarkinDate: 19:24 25-03-07
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On Mon, 26 Mar 2007 07:42:12 +1200, "Roger Dewhurst"
<dewhurst@wave.co.nz> wrote:
>
>"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in
message
>news:o7gd03lqp006plvbl2mv7ou07c9cr0p5l7@4ax.com...
>> On Fri, 23 Mar 2007 11:26:05 +1200, "Roger Dewhurst"
>> <dewhurst@wave.co.nz> wrote:
>>
>> >I want to feed a single pulse of, let us say, 10 to 100 microseconds
>> >duration, into a short length of waveguide and detect that pulse upto
>1000
>> >metres away in another short length of waveguide set to be more or less
>> >co-linear with the first piece of waveguide. Can anyone suggest how I
>might
>> >implement this?
>> >
>> >R
>> >
>>
>> That probably can't be done. No reasonably sized waveguide (smaller
>> than Central Park, say) will propagate signals that slow.
>
>The 'pulse' might be a brief period of carrier wave or even a brief gap in
>the carrier wave. Pulse was probably a poor choice of word on my part. It
>has to start some other electronic equipment which measues time intervals in
>milliseconds (not microseconds!).
>>
>> Why do you want to do this?
>
>See above.
>
>Roger
>
Oh. If you modulate a microwave carrier it becomes feasible. At 1km
distance, horn antannas or parabolas might be better, or yagis for UHF
range.
Line-of-sight optical is interesting, too.
John
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Author: Phil AllisonDate: 20:36 25-03-07
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"Roger Dewhurst" <dewhurst@wave.co.nz
** Sheep Shagger Alert !!
>I want to feed a single pulse of, let us say, 10 to 100 microseconds
> duration, into a short length of waveguide and detect that pulse upto 1000
> metres away in another short length of waveguide set to be more or less
> co-linear with the first piece of waveguide. Can anyone suggest how I
> might
> implement this?
** Err - where did you get the mad idea that a wave guide will create a
narrow beam beyond the guide ?
See anyone do it ?
Or have you just decided in your infinite Kiwi ignorance that the name alone
tells you that.
Baaaahhhhhhhhhh ....
...... Phil
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Author: John LarkinDate: 21:27 25-03-07
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On Mon, 26 Mar 2007 11:04:30 +1200, "Roger Dewhurst"
<dewhurst@wave.co.nz> wrote:
>
>"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in
message
>news:u21e0392rh40741u1meu7v7nnhj67mdm0h@4ax.com...
>> On Mon, 26 Mar 2007 07:42:12 +1200, "Roger Dewhurst"
>> <dewhurst@wave.co.nz> wrote:
>>
>> >
>> >"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com>
wrote in
>message
>> >news:o7gd03lqp006plvbl2mv7ou07c9cr0p5l7@4ax.com...
>> >> On Fri, 23 Mar 2007 11:26:05 +1200, "Roger Dewhurst"
>> >> <dewhurst@wave.co.nz> wrote:
>> >>
>> Oh. If you modulate a microwave carrier it becomes feasible. At 1km
>> distance, horn antannas or parabolas might be better, or yagis for UHF
>> range.
>
>I would like to explore all options.
>
>>
>> Line-of-sight optical is interesting, too.
>
>Very interesting but it might require telescopic sights on the light source
>and receiver.
>
>The transmitter moves every few minutes.
>
>Roger
>
You can buy wireless modems, with small whip antennas, that will work
that far.
John
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Author: Bob MastaDate: 09:55 26-03-07
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On Mon, 26 Mar 2007 07:36:49 +1200, "Roger Dewhurst"
<dewhurst@wave.co.nz> wrote:
>
>"Gareth" <me@privacy.net> wrote in message
>news:yKadnaqxyN4lxJvbRVnyvQA@brightview.com...
>> Roger Dewhurst wrote:
>> > I want to feed a single pulse of, let us say, 10 to 100 microseconds
>> > duration, into a short length of waveguide and detect that pulse upto
>1000
>> > metres away in another short length of waveguide set to be more or less
>> > co-linear with the first piece of waveguide. Can anyone suggest how I
>might
>> > implement this?
>> >
>>
>> Please can you supply a bit more information, in particular:
>>
>> What exactly are you trying to do?
>
>Transfer instantaneously a start signal to some mobile electronic equipment
>which is in line of sight upto 1000 metres away.
>
>>
>> Is there a good reason why want to use waveguide?
>
>I do not want interference by or to other radio transmissions but other
>options are possible. It is just too inconvenient to run a wire except for
>the shorter distances. For short distances the start signal by wire is a
>momentary low triggering pin 2 on a 555.
>
>>
>> What is the carrier frequency of this pulse?
>
>Flexible but around 2 gigahertz. The waveguide can be of any size that is
>reasonably portable and aimable and the carrier wave should match it. For
>preference it will be just outside any recognized band.
>
If you modulate the start signal instead of using a simple pulse,
you could easily make it such that only the matching receiver
can demodulate it properly. True, it won't be as "instantaneous"
since you may need to send several symbols to generate a
decent code, but at 2 GHz you ought to be able to send quite a few
in the time windows you mention.
Best regards,
Bob Masta
D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com
Scope, Spectrum, Spectrogram, Signal Generator
Science with your sound card!
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Author: Rich GriseDate: 18:46 26-03-07
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On Mon, 26 Mar 2007 07:36:49 +1200, Roger Dewhurst wrote:
> "Gareth" <me@privacy.net> wrote in message
>> Roger Dewhurst wrote:
>> > I want to feed a single pulse of, let us say, 10 to 100 microseconds
>> > duration, into a short length of waveguide and detect that pulse upto
> 1000
>> > metres away in another short length of waveguide set to be more or less
>> > co-linear with the first piece of waveguide. Can anyone suggest how I
> might
>> > implement this?
>>
>> Please can you supply a bit more information, in particular:
>>
>> What exactly are you trying to do?
>
> Transfer instantaneously a start signal to some mobile electronic equipment
> which is in line of sight upto 1000 metres away.
>
>> Is there a good reason why want to use waveguide?
>
> I do not want interference by or to other radio transmissions but other
> options are possible. It is just too inconvenient to run a wire except for
> the shorter distances. For short distances the start signal by wire is a
> momentary low triggering pin 2 on a 555.
>
>> What is the carrier frequency of this pulse?
>
> Flexible but around 2 gigahertz. The waveguide can be of any size that is
> reasonably portable and aimable and the carrier wave should match it. For
> preference it will be just outside any recognized band.
>
You could build waveguide feedhorns, but you probably wouldn't get enough
gain to go 1 Km. Get a couple of parabolic dishes, and use the feedhorns
to drive them, and it should be a snap.
http://www.google.com/search?q=waveguide+feedhorn
Good Luck!
Rich
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Author: Roger DewhurstDate: 16:07 27-03-07
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"Rich Grise" <rich@example.net> wrote in message
news:pan.2007.03.26.22.46.41.517848@example.net...
> On Mon, 26 Mar 2007 07:36:49 +1200, Roger Dewhurst wrote:
> > "Gareth" <me@privacy.net> wrote in message
> >> Roger Dewhurst wrote:
How easy is it to feed the signal into one feedhorn and get it back from the
other? Are there easier ways to achieve the required end result? Long
lengths of cable will do it but they are a nuisance to move around. The
signal is required to start a seismograph. The first part of it is a 555
acting as a Schmitt trigger and timer.
Roger
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