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From: Wimpie on 1 Apr 2010 12:42
On 31 mar, 22:38, Joerg <inva...(a)invalid.invalid> wrote:
> Wimpie wrote:
> > On 30 mar, 20:11, n...(a)puntnl.niks (Nico Coesel) wrote:
> >> Every now and then you find something new on your path...
>
> >> I'm working on a wireless device which is going to use a PCB trace as
> >> an antenna. The bitrate is quite high (approx 250kbit) and we decided
> >> to use the 433MHz band because it has little restrictions. The main
> >> problem is the antenna. I managed to put a  115mm (4530 mil) long
> >> trace (1/4 labda monopole) onto the 50mmx80mm (2" x 3.15") board to
> >> form an L shaped antenna. Its fed from a 50 Ohm transmission line
> >> which runs over a reasonable big ground plane (top and bottom stitched
> >> ). So far I was able to gather some info from applications notes and
> >> so on.
>
> >> Ofcourse there is more on the board than just the antenna although I
> >> made sure the antenna runs far away from the dense populated areas.
>
> >> Now the real problem is going to get the antenna tuned. As far as I
> >> can see that takes two steps: getting the antenna to resonate at the
> >> desired frequency and matching the impedance. The gear I have
> >> available is a spectrum analyzer, an oscilloscope, a directional
> >> coupler and an HF generator.
>
> >> I know a vector network analyzer would be the right tool especially
> >> for determining the mismatch, but I'm wondering if I could do without.
> >> If not, I've found this kit.
>
> >>http://www.sdr-kits.net/
>
> >> Looks nice and affordable any comments?
>
> >> --
> >> Failure does not prove something is impossible, failure simply
> >> indicates you are not using the right tools...
> >> nico(a)nctdevpuntnl (punt=.)
> >> --------------------------------------------------------------
>
> > Hello Nico,
>
> > As your quarter wave antenna has a L-shape and runs close (that is <
> > 0.25 lambda) to the ground from were it is fed, the resonant impedance
> > will be probably << 50 Ohms. It will also be narrow band, but that is
> > no problem for a 433 MHz SRD application. It may also reduce unwanted
> > emissions.
>
> > When you tune it to resonance, it will show too low impedance. So you
> > need to match also. Matching can be done by making the lambda/4
> > antenna somewhat longer and add a shunt capacitor, or making it
> > somewhat shorter and add a parallel inductor.
>
> > The gear you have is sufficient. You can feed your construction
> > (inclusive housing) with a common mode decoupled coaxial cable from a
> > 50 Ohms source. Add a 6 dB attenuator if you have doubts about your
> > source.
>
> In fact, that gear is total luxury. When I was a kid we used to tune
> that stuff using a slightly modified old black&white TV set, with a
> surplus analog panel meter dangling off of the AGC voltage. And that
> could not be touched during operation because it was a hot chassis,
> since it had to be an old set where the AGC reacted (somewhat) in the
> absence of sync pulses :-)
>
> --
> Regards, Joerg
>
> http://www.analogconsultants.com/
>
> "gmail" domain blocked because of excessive spam.
> Use another domain or send PM.

Hello Joerg,

The design can be done with less means (you can build a 433 MHz
oscillator yourself, measure frequency with a analog frequency meter
and build a good diode detector for measuring HF power). However, when
you have the equipment, why not use it?

I give some courses on antennas. Many people don’t have a spectrum
analyzer or measuring receiver, so in that case I do the practical
exercises with a diode detector that they can build themselves for
just some Euros. Of course I discuss the quadratic to linear output
transition also. Up to some GHz a return loss bridge can also be build
with SM devices (with more then reasonable directivity).

I like to show "old methods" to show that you can also do good
measurements with primitive means.

Best regards,

Wim
PA3DJS
www.tetech.nl
Please don't forget to remove abc before hitting the "send" button.

From: Joerg on 1 Apr 2010 13:02
Dave Platt wrote:
> In article <4bb3b519.187363265(a)news.planet.nl>,
> Nico Coesel <nico(a)puntnl.niks> wrote:
>
>> Thanks for this extensive recipe. Why isn't information like this in
>> books or appnotes?
>
> Well, it's certainly in *some* books... various of the ARRL handbooks
> and manuals have it.
>

Yep, I was going to say. If you do RF stuff the ARRL Handbook and the
ARRL Antenna Handbook are must-haves. They aren't nearly as expensive as
scientific books but contain serious hands-on information. That's how I
really learned RF stuff, not at the university.

[...]

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: Joerg on 1 Apr 2010 13:15
Wimpie wrote:
> On 31 mar, 22:38, Joerg <inva...(a)invalid.invalid> wrote:
>> Wimpie wrote:
>>> On 30 mar, 20:11, n...(a)puntnl.niks (Nico Coesel) wrote:
>>>> Every now and then you find something new on your path...
>>>> I'm working on a wireless device which is going to use a PCB trace as
>>>> an antenna. The bitrate is quite high (approx 250kbit) and we decided
>>>> to use the 433MHz band because it has little restrictions. The main
>>>> problem is the antenna. I managed to put a 115mm (4530 mil) long
>>>> trace (1/4 labda monopole) onto the 50mmx80mm (2" x 3.15") board to
>>>> form an L shaped antenna. Its fed from a 50 Ohm transmission line
>>>> which runs over a reasonable big ground plane (top and bottom stitched
>>>> ). So far I was able to gather some info from applications notes and
>>>> so on.
>>>> Ofcourse there is more on the board than just the antenna although I
>>>> made sure the antenna runs far away from the dense populated areas.
>>>> Now the real problem is going to get the antenna tuned. As far as I
>>>> can see that takes two steps: getting the antenna to resonate at the
>>>> desired frequency and matching the impedance. The gear I have
>>>> available is a spectrum analyzer, an oscilloscope, a directional
>>>> coupler and an HF generator.
>>>> I know a vector network analyzer would be the right tool especially
>>>> for determining the mismatch, but I'm wondering if I could do without.
>>>> If not, I've found this kit.
>>>> http://www.sdr-kits.net/
>>>> Looks nice and affordable any comments?
>>>> --
>>>> Failure does not prove something is impossible, failure simply
>>>> indicates you are not using the right tools...
>>>> nico(a)nctdevpuntnl (punt=.)
>>>> --------------------------------------------------------------
>>> Hello Nico,
>>> As your quarter wave antenna has a L-shape and runs close (that is <
>>> 0.25 lambda) to the ground from were it is fed, the resonant impedance
>>> will be probably << 50 Ohms. It will also be narrow band, but that is
>>> no problem for a 433 MHz SRD application. It may also reduce unwanted
>>> emissions.
>>> When you tune it to resonance, it will show too low impedance. So you
>>> need to match also. Matching can be done by making the lambda/4
>>> antenna somewhat longer and add a shunt capacitor, or making it
>>> somewhat shorter and add a parallel inductor.
>>> The gear you have is sufficient. You can feed your construction
>>> (inclusive housing) with a common mode decoupled coaxial cable from a
>>> 50 Ohms source. Add a 6 dB attenuator if you have doubts about your
>>> source.
>> In fact, that gear is total luxury. When I was a kid we used to tune
>> that stuff using a slightly modified old black&white TV set, with a
>> surplus analog panel meter dangling off of the AGC voltage. And that
>> could not be touched during operation because it was a hot chassis,
>> since it had to be an old set where the AGC reacted (somewhat) in the
>> absence of sync pulses :-)
>>
>> --
>> Regards, Joerg
>>
>> http://www.analogconsultants.com/
>>
>> "gmail" domain blocked because of excessive spam.
>> Use another domain or send PM.
>
> Hello Joerg,
>
> The design can be done with less means (you can build a 433 MHz
> oscillator yourself, measure frequency with a analog frequency meter
> and build a good diode detector for measuring HF power). However, when
> you have the equipment, why not use it?
>

That's like using a gas grill just because you have it, while the manly
thing would be to make a wood fire in the open pit grill ...

Juist kidding :-)


> I give some courses on antennas. Many people don�t have a spectrum
> analyzer or measuring receiver, so in that case I do the practical
> exercises with a diode detector that they can build themselves for
> just some Euros. Of course I discuss the quadratic to linear output
> transition also. Up to some GHz a return loss bridge can also be build
> with SM devices (with more then reasonable directivity).
>
> I like to show "old methods" to show that you can also do good
> measurements with primitive means.
>

Good man. I wish they'd do the same at universities. I remember coming
to a client with my laptop and some kludgy homebrew wideband probes.
Boss wasn't in yet but I got started. By the time he came out of a
production meeting I had the EMI problem unearthed. "We rented an
Agilent analyzer for you, top of the line, it's in my office" ... "Ahm,
I don't think we'll need it anymore, found the problem with this
detector jig here". He was almost in tears because it must have cost
them almost $1000 for a week's rental.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: Wimpie on 1 Apr 2010 15:31
On 1 abr, 19:15, Joerg <inva...(a)invalid.invalid> wrote:
> Wimpie wrote:
> > On 31 mar, 22:38, Joerg <inva...(a)invalid.invalid> wrote:
> >> Wimpie wrote:
> >>> On 30 mar, 20:11, n...(a)puntnl.niks (Nico Coesel) wrote:
> >>>> Every now and then you find something new on your path...
> >>>> I'm working on a wireless device which is going to use a PCB trace as
> >>>> an antenna. The bitrate is quite high (approx 250kbit) and we decided
> >>>> to use the 433MHz band because it has little restrictions. The main
> >>>> problem is the antenna. I managed to put a  115mm (4530 mil) long
> >>>> trace (1/4 labda monopole) onto the 50mmx80mm (2" x 3.15") board to
> >>>> form an L shaped antenna. Its fed from a 50 Ohm transmission line
> >>>> which runs over a reasonable big ground plane (top and bottom stitched
> >>>> ). So far I was able to gather some info from applications notes and
> >>>> so on.
> >>>> Ofcourse there is more on the board than just the antenna although I
> >>>> made sure the antenna runs far away from the dense populated areas.
> >>>> Now the real problem is going to get the antenna tuned. As far as I
> >>>> can see that takes two steps: getting the antenna to resonate at the
> >>>> desired frequency and matching the impedance. The gear I have
> >>>> available is a spectrum analyzer, an oscilloscope, a directional
> >>>> coupler and an HF generator.
> >>>> I know a vector network analyzer would be the right tool especially
> >>>> for determining the mismatch, but I'm wondering if I could do without.
> >>>> If not, I've found this kit.
> >>>>http://www.sdr-kits.net/
> >>>> Looks nice and affordable any comments?
> >>>> --
> >>>> Failure does not prove something is impossible, failure simply
> >>>> indicates you are not using the right tools...
> >>>> nico(a)nctdevpuntnl (punt=.)
> >>>> --------------------------------------------------------------
> >>> Hello Nico,
> >>> As your quarter wave antenna has a L-shape and runs close (that is <
> >>> 0.25 lambda) to the ground from were it is fed, the resonant impedance
> >>> will be probably << 50 Ohms. It will also be narrow band, but that is
> >>> no problem for a 433 MHz SRD application. It may also reduce unwanted
> >>> emissions.
> >>> When you tune it to resonance, it will show too low impedance. So you
> >>> need to match also. Matching can be done by making the lambda/4
> >>> antenna somewhat longer and add a shunt capacitor, or making it
> >>> somewhat shorter and add a parallel inductor.
> >>> The gear you have is sufficient. You can feed your construction
> >>> (inclusive housing) with a common mode decoupled coaxial cable from a
> >>> 50 Ohms source. Add a 6 dB attenuator if you have doubts about your
> >>> source.
> >> In fact, that gear is total luxury. When I was a kid we used to tune
> >> that stuff using a slightly modified old black&white TV set, with a
> >> surplus analog panel meter dangling off of the AGC voltage. And that
> >> could not be touched during operation because it was a hot chassis,
> >> since it had to be an old set where the AGC reacted (somewhat) in the
> >> absence of sync pulses :-)
>
> >> --
> >> Regards, Joerg
>
> >>http://www.analogconsultants.com/
>
> >> "gmail" domain blocked because of excessive spam.
> >> Use another domain or send PM.
>
> > Hello Joerg,
>
> > The design can be done with less means (you can build a 433 MHz
> > oscillator yourself, measure frequency with a analog frequency meter
> > and build a good diode detector for measuring HF power). However, when
> > you have the equipment, why not use it?
>
> That's like using a gas grill just because you have it, while the manly
> thing would be to make a wood fire in the open pit grill ...
>
> Juist kidding :-)
>
> > I give some courses on antennas. Many people don’t have a spectrum
> > analyzer or measuring receiver, so in that case I do the practical
> > exercises with a diode detector that they can build themselves for
> > just some Euros. Of course I discuss the quadratic to linear output
> > transition also. Up to some GHz a return loss bridge can also be build
> > with SM devices (with more then reasonable directivity).
>
> > I like to show "old methods" to show that you can also do good
> > measurements with primitive means.
>
> Good man. I wish they'd do the same at universities. I remember coming
> to a client with my laptop and some kludgy homebrew wideband probes.
> Boss wasn't in yet but I got started. By the time he came out of a
> production meeting I had the EMI problem unearthed. "We rented an
> Agilent analyzer for you, top of the line, it's in my office" ... "Ahm,
> I don't think we'll need it anymore, found the problem with this
> detector jig here". He was almost in tears because it must have cost
> them almost $1000 for a week's rental.
>

Hello Joerg,

Painfull for your Boss.

Such situations sound very familiar to me. Sometimes they don’t
believe an opinion or don't take you seriously when you don't show an
(expensive) Agilent or Rohde & Schwarz cabinet with many push buttons.
It doesn't matter what it is, it just has to look impressive....

Best regards,


Wim
PA3DJS
www.tetech.nl
Without abc, the mail address is valid.

[rest deleted]
From: Nico Coesel on 1 Apr 2010 16:38
Wimpie <wimabctel(a)tetech.nl> wrote:

>On 1 abr, 19:15, Joerg <inva...(a)invalid.invalid> wrote:
>> Wimpie wrote:
>> > On 31 mar, 22:38, Joerg <inva...(a)invalid.invalid> wrote:
>> >> Wimpie wrote:
>> >>> On 30 mar, 20:11, n...(a)puntnl.niks (Nico Coesel) wrote:
>> >>>> Every now and then you find something new on your path...
>> >>>> I'm working on a wireless device which is going to use a PCB trace a=
>s
>> >>>> an antenna. The bitrate is quite high (approx 250kbit) and we decide=
>d
>> >>>> to use the 433MHz band because it has little restrictions. The main
>> >>>> problem is the antenna. I managed to put a =A0115mm (4530 mil) long
>> >>>> trace (1/4 labda monopole) onto the 50mmx80mm (2" x 3.15") board to
>> >>>> form an L shaped antenna. Its fed from a 50 Ohm transmission line
>> >>>> which runs over a reasonable big ground plane (top and bottom stitch=
>ed
>> >>>> ). So far I was able to gather some info from applications notes and
>> >>>> so on.
>> >>>> Ofcourse there is more on the board than just the antenna although I
>> >>>> made sure the antenna runs far away from the dense populated areas.
>> >>>> Now the real problem is going to get the antenna tuned. As far as I
>> >>>> can see that takes two steps: getting the antenna to resonate at the
>> >>>> desired frequency and matching the impedance. The gear I have
>> >>>> available is a spectrum analyzer, an oscilloscope, a directional
>> >>>> coupler and an HF generator.
>> >>>> I know a vector network analyzer would be the right tool especially
>> >>>> for determining the mismatch, but I'm wondering if I could do withou=
>t.
>> >>>> If not, I've found this kit.
>> >>>>http://www.sdr-kits.net/
>> >>>> Looks nice and affordable any comments?
>> >>>> --
>> >>>> Failure does not prove something is impossible, failure simply
>> >>>> indicates you are not using the right tools...
>> >>>> nico(a)nctdevpuntnl (punt=3D.)
>> >>>> --------------------------------------------------------------
>> >>> Hello Nico,
>> >>> As your quarter wave antenna has a L-shape and runs close (that is <
>> >>> 0.25 lambda) to the ground from were it is fed, the resonant impedanc=
>e
>> >>> will be probably << 50 Ohms. It will also be narrow band, but that is
>> >>> no problem for a 433 MHz SRD application. It may also reduce unwanted
>> >>> emissions.
>> >>> When you tune it to resonance, it will show too low impedance. So you
>> >>> need to match also. Matching can be done by making the lambda/4
>> >>> antenna somewhat longer and add a shunt capacitor, or making it
>> >>> somewhat shorter and add a parallel inductor.
>> >>> The gear you have is sufficient. You can feed your construction
>> >>> (inclusive housing) with a common mode decoupled coaxial cable from a
>> >>> 50 Ohms source. Add a 6 dB attenuator if you have doubts about your
>> >>> source.
>> >> In fact, that gear is total luxury. When I was a kid we used to tune
>> >> that stuff using a slightly modified old black&white TV set, with a
>> >> surplus analog panel meter dangling off of the AGC voltage. And that
>> >> could not be touched during operation because it was a hot chassis,
>> >> since it had to be an old set where the AGC reacted (somewhat) in the
>> >> absence of sync pulses :-)
>>
>> >> --
>> >> Regards, Joerg
>>
>> >>http://www.analogconsultants.com/
>>
>> >> "gmail" domain blocked because of excessive spam.
>> >> Use another domain or send PM.
>>
>> > Hello Joerg,
>>
>> > The design can be done with less means (you can build a 433 MHz
>> > oscillator yourself, measure frequency with a analog frequency meter
>> > and build a good diode detector for measuring HF power). However, when
>> > you have the equipment, why not use it?
>>
>> That's like using a gas grill just because you have it, while the manly
>> thing would be to make a wood fire in the open pit grill ...
>>
>> Juist kidding :-)
>>
>> > I give some courses on antennas. Many people don=92t have a spectrum
>> > analyzer or measuring receiver, so in that case I do the practical
>> > exercises with a diode detector that they can build themselves for
>> > just some Euros. Of course I discuss the quadratic to linear output
>> > transition also. Up to some GHz a return loss bridge can also be build
>> > with SM devices (with more then reasonable directivity).
>>
>> > I like to show "old methods" to show that you can also do good
>> > measurements with primitive means.
>>
>> Good man. I wish they'd do the same at universities. I remember coming
>> to a client with my laptop and some kludgy homebrew wideband probes.
>> Boss wasn't in yet but I got started. By the time he came out of a
>> production meeting I had the EMI problem unearthed. "We rented an
>> Agilent analyzer for you, top of the line, it's in my office" ... "Ahm,
>> I don't think we'll need it anymore, found the problem with this
>> detector jig here". He was almost in tears because it must have cost
>> them almost $1000 for a week's rental.
>>
>
>Hello Joerg,
>
>Painfull for your Boss.
>
>Such situations sound very familiar to me. Sometimes they don=92t
>believe an opinion or don't take you seriously when you don't show an
>(expensive) Agilent or Rohde & Schwarz cabinet with many push buttons.
>It doesn't matter what it is, it just has to look impressive....

If it makes all of you feel better: the SA is a cheap Atten model
which we bought to hunt and solve EMC problems. Now it comes in handy
again. The HF generator is a stone age R&S SMDA and the scope is an
analog 470MHz Lecroy-Iwatsu.

--
Failure does not prove something is impossible, failure simply
indicates you are not using the right tools...
nico(a)nctdevpuntnl (punt=.)
--------------------------------------------------------------
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