low MHz connector design consultant
in [Design]
|
From: John Larkin on 1 May 2010 18:16 On Sat, 01 May 2010 21:19:52 +0100, Baron <baron.nospam(a)linuxmaniac.nospam.net> wrote: >mpm Inscribed thus: > >> On Apr 30, 10:58�pm, "k...(a)att.bizzzzzzzzzzzz" >> <k...(a)att.bizzzzzzzzzzzz> wrote: >>> On Fri, 30 Apr 2010 18:39:21 -0700 (PDT), mpm <mpmill...(a)aol.com> >>> wrote: >>> >On Apr 30, 4:31�pm, Wimpie <wimabc...(a)tetech.nl> wrote: >>> >> On 30 abr, 13:54, "mook johnson" <m...(a)mook.net> wrote: >>> >>> >> > "John Larkin" <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote >>> >> > in message >>> >>> >> >news:ql9kt5tg7s7e5q7pb460gcdig4r00jjmrj(a)4ax.com... >>> >>> >> > > On Thu, 29 Apr 2010 18:30:41 -0500, "mook johnson" >>> >> > > <m...(a)mook.net> wrote: >>> >>> >> > >>Gents, >>> >>> >> > >>I looking for a consultant that can assist in the design of a >>> >> > >>custom military style connector with controlled characteristic >>> >> > >>impedance and insertion loss between two terminals in the 1MHz >>> >> > >>- 20MHz frequency range. >>> >>> >> > >>This connector is special because is the application so an off >>> >> > >>the shelf component will not work. >>> >>> >> > >>Any leads where I can start looking for such a consultant? >>> >>> >> > >>thanks >>> >>> >> > > There are so many military connectors, including ones for wild >>> >> > > environments, hermetic, etc, some standard part might work. >>> >>> >> > > 20 MHz isn't very demanding. Most any mil connector will be >>> >> > > "matched" to any impedance at 20 MHz. Wavelength is 15 meters! >>> >>> >> > > John >>> >>> >> > The connector I need goes into environments that far exceed >>> >> > military applications but the physical concept is similar. �We >>> >> > have an in-house connector company that makes these connectors >>> >> > for us but they have never had to deal with never greater than >>> >> > >200KHz signals before. �We tried using our regular connectors >>> >> > for this application and the impedance mismatch and insertion >>> >> > loss were extreme at 5 - 20MHz. �The Zo mismatched by 50% and >>> >> > was not stable above 1MHz and had several resonant modes. >>> >> > Insertion loss something on the order is 6dB/connector and we'll >>> >> > have a couple dozen in series on this line. �The number of >>> >> > series connection is the is the rub and it is unavoidable, non >>> >> > negotiable. >>> >>> >> > There are some commercial plastic connectors that tested very >>> >> > well (just to validate our test setup) with good impedance >>> >> > match/stability (+/- 5%) and low insertion loss (.1dB/connector) >>> >> > but they won't take the environment. >>> >>> >> > I'm looking for a consultant that can provide either of the >>> >> > following >>> >>> >> > 1) model a connector that is already designed but not made >>> >> > (basically review the in-house company proposed design) and >>> >> > simulate the high frequency response of the design. >>> >>> >> > 2) Give direction for the connector design based on constraints >>> >> > of material choices, physical size and geometry to meet the >>> >> > desired electrical signal characteristics while withstanding the >>> >> > environmental conditions. >>> >>> >> > The cut and try approach based on simple equations has a long >>> >> > cycle time. I'm looking to improve my chances of getting it >>> >> > right the first time. >>> >>> >> Hello Mook, >>> >>> >> When you have already a company that knows mechanical design and >>> >> reliability issues, you only need the EM-field guy. � When you can >>> >> keep the mechanical guys and the EM-field guy in one room, this >>> >> should converge to a solution fast. >>> >>> >> One familiar with the concept of characteristic impedance, complex >>> >> propagation constant (contains both complex epsilon and >>> >> permeability) and know how to measure the material constants can >>> >> do the job. >>> >>> >> What about: required Return Loss, characteristic impedance, >>> >> Insertion loss, propagation delay, size, �cross section, (coaxial, >>> >> square, symmetrical, etc), peak and average power, etc? >>> >>> >> Kind regards, >>> >>> >> Wim >>> >> PA3DJSwww.tetech.nl >>> >> when you delete abc first, PM will reach me- Hide quoted text - >>> >>> >> - Show quoted text - >>> >>> >I have a question for you: >>> >>> >Do you believe that the characteristic impedance is dependent on the >>> >length of the coax? >>> >(For the ratio of transverse electric field to transverse magnetic >>> >field launched on a transmission line of infinite length.) >>> >>> "infinite length" <> "independent of length"- Hide quoted text - >>> >>> - Show quoted text - >> >> Not sure I understand your cryptic post. >> >> That is how characteristic impedance is classically defined, and I'm >> asking him if he believes that characteristic impedance is dependent >> on length? > >For co-axial cables its a function of the ratio of the diameters of the >conductors modified by the dielectric constant of the insulator, or for >twin conductor the spacing between them and the dielectric constant of >the insulator. >ie (impedance = (138 / e^(1/2)) * log (D/d)) That's the simplified lossless mid-frequency model. At low frequencies, Zo goes up because of resistive losses. At very high frequencies, you get moding and complex whoopie-doos. None of that matters if the coax or connectors are a tiny fraction of a wavelength, as in the OP's case; they devolve to a small lumped capacitance. How he can get 6 dB of loss at low MHz is a mystery to me. John
From: krw on 1 May 2010 18:49 On Sat, 1 May 2010 12:00:27 -0700 (PDT), mpm <mpmillard(a)aol.com> wrote: >On May 1, 9:17�am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> >wrote: >> On Sat, 1 May 2010 00:34:48 -0700 (PDT), mpm <mpmill...(a)aol.com> wrote: >> >On Apr 30, 10:58�pm, "k...(a)att.bizzzzzzzzzzzz" >> ><k...(a)att.bizzzzzzzzzzzz> wrote: >> >> On Fri, 30 Apr 2010 18:39:21 -0700 (PDT), mpm <mpmill...(a)aol.com> wrote: >> >> >On Apr 30, 4:31�pm, Wimpie <wimabc...(a)tetech.nl> wrote: >> >> >> On 30 abr, 13:54, "mook johnson" <m...(a)mook.net> wrote: >> >> >> >> > "John Larkin" <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote in message >> >> >> >> >news:ql9kt5tg7s7e5q7pb460gcdig4r00jjmrj(a)4ax.com... >> >> >> >> > > On Thu, 29 Apr 2010 18:30:41 -0500, "mook johnson" <m...(a)mook.net> >> >> >> > > wrote: >> >> >> >> > >>Gents, >> >> >> >> > >>I looking for a consultant that can assist in the design of a custom >> >> >> > >>military style connector with controlled characteristic impedance and >> >> >> > >>insertion loss between two terminals in the 1MHz - 20MHz frequency range. >> >> >> >> > >>This connector is special because is the application so an off the shelf >> >> >> > >>component will not work. >> >> >> >> > >>Any leads where I can start looking for such a consultant? >> >> >> >> > >>thanks >> >> >> >> > > There are so many military connectors, including ones for wild >> >> >> > > environments, hermetic, etc, some standard part might work. >> >> >> >> > > 20 MHz isn't very demanding. Most any mil connector will be "matched" >> >> >> > > to any impedance at 20 MHz. Wavelength is 15 meters! >> >> >> >> > > John >> >> >> >> > The connector I need goes into environments that far exceed military >> >> >> > applications but the physical concept is similar. �We have an in-house >> >> >> > connector company that makes these connectors for us but they have never had >> >> >> > to deal with never greater than >200KHz signals before. �We tried using our >> >> >> > regular connectors for this application and the impedance mismatch and >> >> >> > insertion loss were extreme at 5 - 20MHz. �The Zo mismatched by 50% and was >> >> >> > not stable above 1MHz and had several resonant modes. Insertion loss >> >> >> > something on the order is 6dB/connector and we'll have a couple dozen in >> >> >> > series on this line. �The number of series connection is the is the rub and >> >> >> > it is unavoidable, non negotiable. >> >> >> >> > There are some commercial plastic connectors that tested very well (just to >> >> >> > validate our test setup) with good impedance match/stability (+/- 5%) and >> >> >> > low insertion loss (.1dB/connector) but they won't take the environment. >> >> >> >> > I'm looking for a consultant that can provide either of the following >> >> >> >> > 1) model a connector that is already designed but not made (basically review >> >> >> > the in-house company proposed design) and simulate the high frequency >> >> >> > response of the design. >> >> >> >> > 2) Give direction for the connector design based on constraints of material >> >> >> > choices, physical size and geometry to meet the desired electrical signal >> >> >> > characteristics while withstanding the environmental conditions. >> >> >> >> > The cut and try approach based on simple equations has a long cycle time. >> >> >> > I'm looking to improve my chances of getting it right the first time. >> >> >> >> Hello Mook, >> >> >> >> When you have already a company that knows mechanical design and >> >> >> reliability issues, you only need the EM-field guy. � When you can >> >> >> keep the mechanical guys and the EM-field guy in one room, this should >> >> >> converge to a solution fast. >> >> >> >> One familiar with the concept of characteristic impedance, complex >> >> >> propagation constant (contains both complex epsilon and permeability) >> >> >> and know how to measure the material constants can do the job. >> >> >> >> What about: required Return Loss, characteristic impedance, Insertion >> >> >> loss, propagation delay, size, �cross section, (coaxial, square, >> >> >> symmetrical, etc), peak and average power, etc? >> >> >> >> Kind regards, >> >> >> >> Wim >> >> >> PA3DJSwww.tetech.nl >> >> >> when you delete abc first, PM will reach me- Hide quoted text - >> >> >> >> - Show quoted text - >> >> >> >I have a question for you: >> >> >> >Do you believe that the characteristic impedance is dependent on the >> >> >length of the coax? >> >> >(For the ratio of transverse electric field to transverse magnetic >> >> >field launched on a transmission line of infinite length.) >> >> >> "infinite length" <> "independent of length"- Hide quoted text - >> >> >> - Show quoted text - >> >> >Not sure I understand your cryptic post. >> >> >That is how characteristic impedance is classically defined, and I'm >> >asking him if he believes that characteristic impedance is dependent >> >on length? >> >> But you talk about dependency on length and "infinite" length in the same >> paragraph. �You can't have both variable length (which would include short) >> and a dependency on being "infinite".- Hide quoted text - >> >> - Show quoted text - > >OK - Maybe I could have stated that a little better.... (?) > >My point: Does the length of the coax (or connector - since that's >the topic of this post) have anything to do with characteristic >impedance? >And NOTE THAT THE DEFINITION OF CHARACTERISTIC IMPEDANCE ITSELF >INCLUDES AN INFINITE LENGTH. (Which a connector DOES NOT have.) So you're asking if the characteristic impedance of a piece of coax varies with length, when in the same question you define "characteristic impedance" to be impedance (V/I) of an infinite length coax. Kinda silly to ask a question when your question defines the answer, no? Are blue birds blue? >If I ask that question without mentioning that the various equations >for characteristic impedance are derived from terms that include >inductance per unit length (even if they later cancel out), then the >question is absolutely meaningless. No, one assumes that the term "characteristic impedance" means something in a group with the name sci.electronics.design. >So, I am PURPOSELY avoiding any possibility of a circular definition >when I ask this question. No avoidance at all. Your question was self-circular. >Do you understand now? Why you asked the question the way you did? No, I have no idea. >Once you understand the question, we will look at whether or not the >traditional equations for characteristic impedance are even valid >(hint: I don't think they are!), given that they do not agree when >applied to antennas, (which certainly have a length component). And, >since they depend on antenna length, it contradicts the fundamental >definitions. Even more interesting, the various calculations do not >yield identical results, particularly if you consider an antenna to be >a transmission line immersed in three-dimensional space. Perhaps the (simplified, btw) equations don't have enough terms to describe every possibility that you think they should cover.
From: Joerg on 1 May 2010 20:47 John Larkin wrote: > On Sat, 01 May 2010 21:19:52 +0100, Baron > <baron.nospam(a)linuxmaniac.nospam.net> wrote: > >> mpm Inscribed thus: >> >>> On Apr 30, 10:58 pm, "k...(a)att.bizzzzzzzzzzzz" >>> <k...(a)att.bizzzzzzzzzzzz> wrote: >>>> On Fri, 30 Apr 2010 18:39:21 -0700 (PDT), mpm <mpmill...(a)aol.com> >>>> wrote: >>>>> On Apr 30, 4:31 pm, Wimpie <wimabc...(a)tetech.nl> wrote: >>>>>> On 30 abr, 13:54, "mook johnson" <m...(a)mook.net> wrote: >>>>>>> "John Larkin" <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote >>>>>>> in message >>>>>>> news:ql9kt5tg7s7e5q7pb460gcdig4r00jjmrj(a)4ax.com... >>>>>>>> On Thu, 29 Apr 2010 18:30:41 -0500, "mook johnson" >>>>>>>> <m...(a)mook.net> wrote: >>>>>>>>> Gents, >>>>>>>>> I looking for a consultant that can assist in the design of a >>>>>>>>> custom military style connector with controlled characteristic >>>>>>>>> impedance and insertion loss between two terminals in the 1MHz >>>>>>>>> - 20MHz frequency range. >>>>>>>>> This connector is special because is the application so an off >>>>>>>>> the shelf component will not work. >>>>>>>>> Any leads where I can start looking for such a consultant? >>>>>>>>> thanks >>>>>>>> There are so many military connectors, including ones for wild >>>>>>>> environments, hermetic, etc, some standard part might work. >>>>>>>> 20 MHz isn't very demanding. Most any mil connector will be >>>>>>>> "matched" to any impedance at 20 MHz. Wavelength is 15 meters! >>>>>>>> John >>>>>>> The connector I need goes into environments that far exceed >>>>>>> military applications but the physical concept is similar. We >>>>>>> have an in-house connector company that makes these connectors >>>>>>> for us but they have never had to deal with never greater than >>>>>>>> 200KHz signals before. We tried using our regular connectors >>>>>>> for this application and the impedance mismatch and insertion >>>>>>> loss were extreme at 5 - 20MHz. The Zo mismatched by 50% and >>>>>>> was not stable above 1MHz and had several resonant modes. >>>>>>> Insertion loss something on the order is 6dB/connector and we'll >>>>>>> have a couple dozen in series on this line. The number of >>>>>>> series connection is the is the rub and it is unavoidable, non >>>>>>> negotiable. >>>>>>> There are some commercial plastic connectors that tested very >>>>>>> well (just to validate our test setup) with good impedance >>>>>>> match/stability (+/- 5%) and low insertion loss (.1dB/connector) >>>>>>> but they won't take the environment. >>>>>>> I'm looking for a consultant that can provide either of the >>>>>>> following >>>>>>> 1) model a connector that is already designed but not made >>>>>>> (basically review the in-house company proposed design) and >>>>>>> simulate the high frequency response of the design. >>>>>>> 2) Give direction for the connector design based on constraints >>>>>>> of material choices, physical size and geometry to meet the >>>>>>> desired electrical signal characteristics while withstanding the >>>>>>> environmental conditions. >>>>>>> The cut and try approach based on simple equations has a long >>>>>>> cycle time. I'm looking to improve my chances of getting it >>>>>>> right the first time. >>>>>> Hello Mook, >>>>>> When you have already a company that knows mechanical design and >>>>>> reliability issues, you only need the EM-field guy. When you can >>>>>> keep the mechanical guys and the EM-field guy in one room, this >>>>>> should converge to a solution fast. >>>>>> One familiar with the concept of characteristic impedance, complex >>>>>> propagation constant (contains both complex epsilon and >>>>>> permeability) and know how to measure the material constants can >>>>>> do the job. >>>>>> What about: required Return Loss, characteristic impedance, >>>>>> Insertion loss, propagation delay, size, cross section, (coaxial, >>>>>> square, symmetrical, etc), peak and average power, etc? >>>>>> Kind regards, >>>>>> Wim >>>>>> PA3DJSwww.tetech.nl >>>>>> when you delete abc first, PM will reach me- Hide quoted text - >>>>>> - Show quoted text - >>>>> I have a question for you: >>>>> Do you believe that the characteristic impedance is dependent on the >>>>> length of the coax? >>>>> (For the ratio of transverse electric field to transverse magnetic >>>>> field launched on a transmission line of infinite length.) >>>> "infinite length" <> "independent of length"- Hide quoted text - >>>> >>>> - Show quoted text - >>> Not sure I understand your cryptic post. >>> >>> That is how characteristic impedance is classically defined, and I'm >>> asking him if he believes that characteristic impedance is dependent >>> on length? >> For co-axial cables its a function of the ratio of the diameters of the >> conductors modified by the dielectric constant of the insulator, or for >> twin conductor the spacing between them and the dielectric constant of >> the insulator. >> ie (impedance = (138 / e^(1/2)) * log (D/d)) > > That's the simplified lossless mid-frequency model. At low > frequencies, Zo goes up because of resistive losses. At very high > frequencies, you get moding and complex whoopie-doos. None of that > matters if the coax or connectors are a tiny fraction of a wavelength, > as in the OP's case; they devolve to a small lumped capacitance. > > How he can get 6 dB of loss at low MHz is a mystery to me. > Send in a kilowatt and see what starts to smoke? I know, I know, that was facetious. Profound apologies :-) -- SCNR, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: krw on 1 May 2010 21:15 On Sat, 01 May 2010 17:47:51 -0700, Joerg <invalid(a)invalid.invalid> wrote: >John Larkin wrote: >> On Sat, 01 May 2010 21:19:52 +0100, Baron >> <baron.nospam(a)linuxmaniac.nospam.net> wrote: >> >>> mpm Inscribed thus: >>> >>>> On Apr 30, 10:58 pm, "k...(a)att.bizzzzzzzzzzzz" >>>> <k...(a)att.bizzzzzzzzzzzz> wrote: >>>>> On Fri, 30 Apr 2010 18:39:21 -0700 (PDT), mpm <mpmill...(a)aol.com> >>>>> wrote: >>>>>> On Apr 30, 4:31 pm, Wimpie <wimabc...(a)tetech.nl> wrote: >>>>>>> On 30 abr, 13:54, "mook johnson" <m...(a)mook.net> wrote: >>>>>>>> "John Larkin" <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote >>>>>>>> in message >>>>>>>> news:ql9kt5tg7s7e5q7pb460gcdig4r00jjmrj(a)4ax.com... >>>>>>>>> On Thu, 29 Apr 2010 18:30:41 -0500, "mook johnson" >>>>>>>>> <m...(a)mook.net> wrote: >>>>>>>>>> Gents, >>>>>>>>>> I looking for a consultant that can assist in the design of a >>>>>>>>>> custom military style connector with controlled characteristic >>>>>>>>>> impedance and insertion loss between two terminals in the 1MHz >>>>>>>>>> - 20MHz frequency range. >>>>>>>>>> This connector is special because is the application so an off >>>>>>>>>> the shelf component will not work. >>>>>>>>>> Any leads where I can start looking for such a consultant? >>>>>>>>>> thanks >>>>>>>>> There are so many military connectors, including ones for wild >>>>>>>>> environments, hermetic, etc, some standard part might work. >>>>>>>>> 20 MHz isn't very demanding. Most any mil connector will be >>>>>>>>> "matched" to any impedance at 20 MHz. Wavelength is 15 meters! >>>>>>>>> John >>>>>>>> The connector I need goes into environments that far exceed >>>>>>>> military applications but the physical concept is similar. We >>>>>>>> have an in-house connector company that makes these connectors >>>>>>>> for us but they have never had to deal with never greater than >>>>>>>>> 200KHz signals before. We tried using our regular connectors >>>>>>>> for this application and the impedance mismatch and insertion >>>>>>>> loss were extreme at 5 - 20MHz. The Zo mismatched by 50% and >>>>>>>> was not stable above 1MHz and had several resonant modes. >>>>>>>> Insertion loss something on the order is 6dB/connector and we'll >>>>>>>> have a couple dozen in series on this line. The number of >>>>>>>> series connection is the is the rub and it is unavoidable, non >>>>>>>> negotiable. >>>>>>>> There are some commercial plastic connectors that tested very >>>>>>>> well (just to validate our test setup) with good impedance >>>>>>>> match/stability (+/- 5%) and low insertion loss (.1dB/connector) >>>>>>>> but they won't take the environment. >>>>>>>> I'm looking for a consultant that can provide either of the >>>>>>>> following >>>>>>>> 1) model a connector that is already designed but not made >>>>>>>> (basically review the in-house company proposed design) and >>>>>>>> simulate the high frequency response of the design. >>>>>>>> 2) Give direction for the connector design based on constraints >>>>>>>> of material choices, physical size and geometry to meet the >>>>>>>> desired electrical signal characteristics while withstanding the >>>>>>>> environmental conditions. >>>>>>>> The cut and try approach based on simple equations has a long >>>>>>>> cycle time. I'm looking to improve my chances of getting it >>>>>>>> right the first time. >>>>>>> Hello Mook, >>>>>>> When you have already a company that knows mechanical design and >>>>>>> reliability issues, you only need the EM-field guy. When you can >>>>>>> keep the mechanical guys and the EM-field guy in one room, this >>>>>>> should converge to a solution fast. >>>>>>> One familiar with the concept of characteristic impedance, complex >>>>>>> propagation constant (contains both complex epsilon and >>>>>>> permeability) and know how to measure the material constants can >>>>>>> do the job. >>>>>>> What about: required Return Loss, characteristic impedance, >>>>>>> Insertion loss, propagation delay, size, cross section, (coaxial, >>>>>>> square, symmetrical, etc), peak and average power, etc? >>>>>>> Kind regards, >>>>>>> Wim >>>>>>> PA3DJSwww.tetech.nl >>>>>>> when you delete abc first, PM will reach me- Hide quoted text - >>>>>>> - Show quoted text - >>>>>> I have a question for you: >>>>>> Do you believe that the characteristic impedance is dependent on the >>>>>> length of the coax? >>>>>> (For the ratio of transverse electric field to transverse magnetic >>>>>> field launched on a transmission line of infinite length.) >>>>> "infinite length" <> "independent of length"- Hide quoted text - >>>>> >>>>> - Show quoted text - >>>> Not sure I understand your cryptic post. >>>> >>>> That is how characteristic impedance is classically defined, and I'm >>>> asking him if he believes that characteristic impedance is dependent >>>> on length? >>> For co-axial cables its a function of the ratio of the diameters of the >>> conductors modified by the dielectric constant of the insulator, or for >>> twin conductor the spacing between them and the dielectric constant of >>> the insulator. >>> ie (impedance = (138 / e^(1/2)) * log (D/d)) >> >> That's the simplified lossless mid-frequency model. At low >> frequencies, Zo goes up because of resistive losses. At very high >> frequencies, you get moding and complex whoopie-doos. None of that >> matters if the coax or connectors are a tiny fraction of a wavelength, >> as in the OP's case; they devolve to a small lumped capacitance. >> >> How he can get 6 dB of loss at low MHz is a mystery to me. >> > >Send in a kilowatt and see what starts to smoke? Smoke the "phut" out of it? >I know, I know, that was facetious. Profound apologies :-) Yes, with that kind of lump in the line, the transmitter would likely go "phut" phirst.
From: mpm on 1 May 2010 23:45
On May 1, 5:49 pm, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> wrote: > On Sat, 1 May 2010 12:00:27 -0700 (PDT), mpm <mpmill...(a)aol.com> wrote: > >On May 1, 9:17 am, "k...(a)att.bizzzzzzzzzzzz" <k...(a)att.bizzzzzzzzzzzz> > >wrote: > >> On Sat, 1 May 2010 00:34:48 -0700 (PDT), mpm <mpmill...(a)aol.com> wrote: > >> >On Apr 30, 10:58 pm, "k...(a)att.bizzzzzzzzzzzz" > >> ><k...(a)att.bizzzzzzzzzzzz> wrote: > >> >> On Fri, 30 Apr 2010 18:39:21 -0700 (PDT), mpm <mpmill...(a)aol.com> wrote: > >> >> >On Apr 30, 4:31 pm, Wimpie <wimabc...(a)tetech.nl> wrote: > >> >> >> On 30 abr, 13:54, "mook johnson" <m...(a)mook.net> wrote: > > >> >> >> > "John Larkin" <jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote in message > > >> >> >> >news:ql9kt5tg7s7e5q7pb460gcdig4r00jjmrj(a)4ax.com... > > >> >> >> > > On Thu, 29 Apr 2010 18:30:41 -0500, "mook johnson" <m...(a)mook.net> > >> >> >> > > wrote: > > >> >> >> > >>Gents, > > >> >> >> > >>I looking for a consultant that can assist in the design of a custom > >> >> >> > >>military style connector with controlled characteristic impedance and > >> >> >> > >>insertion loss between two terminals in the 1MHz - 20MHz frequency range. > > >> >> >> > >>This connector is special because is the application so an off the shelf > >> >> >> > >>component will not work. > > >> >> >> > >>Any leads where I can start looking for such a consultant? > > >> >> >> > >>thanks > > >> >> >> > > There are so many military connectors, including ones for wild > >> >> >> > > environments, hermetic, etc, some standard part might work. > > >> >> >> > > 20 MHz isn't very demanding. Most any mil connector will be "matched" > >> >> >> > > to any impedance at 20 MHz. Wavelength is 15 meters! > > >> >> >> > > John > > >> >> >> > The connector I need goes into environments that far exceed military > >> >> >> > applications but the physical concept is similar. We have an in-house > >> >> >> > connector company that makes these connectors for us but they have never had > >> >> >> > to deal with never greater than >200KHz signals before. We tried using our > >> >> >> > regular connectors for this application and the impedance mismatch and > >> >> >> > insertion loss were extreme at 5 - 20MHz. The Zo mismatched by 50% and was > >> >> >> > not stable above 1MHz and had several resonant modes. Insertion loss > >> >> >> > something on the order is 6dB/connector and we'll have a couple dozen in > >> >> >> > series on this line. The number of series connection is the is the rub and > >> >> >> > it is unavoidable, non negotiable. > > >> >> >> > There are some commercial plastic connectors that tested very well (just to > >> >> >> > validate our test setup) with good impedance match/stability (+/- 5%) and > >> >> >> > low insertion loss (.1dB/connector) but they won't take the environment. > > >> >> >> > I'm looking for a consultant that can provide either of the following > > >> >> >> > 1) model a connector that is already designed but not made (basically review > >> >> >> > the in-house company proposed design) and simulate the high frequency > >> >> >> > response of the design. > > >> >> >> > 2) Give direction for the connector design based on constraints of material > >> >> >> > choices, physical size and geometry to meet the desired electrical signal > >> >> >> > characteristics while withstanding the environmental conditions. > > >> >> >> > The cut and try approach based on simple equations has a long cycle time. > >> >> >> > I'm looking to improve my chances of getting it right the first time. > > >> >> >> Hello Mook, > > >> >> >> When you have already a company that knows mechanical design and > >> >> >> reliability issues, you only need the EM-field guy. When you can > >> >> >> keep the mechanical guys and the EM-field guy in one room, this should > >> >> >> converge to a solution fast. > > >> >> >> One familiar with the concept of characteristic impedance, complex > >> >> >> propagation constant (contains both complex epsilon and permeability) > >> >> >> and know how to measure the material constants can do the job. > > >> >> >> What about: required Return Loss, characteristic impedance, Insertion > >> >> >> loss, propagation delay, size, cross section, (coaxial, square, > >> >> >> symmetrical, etc), peak and average power, etc? > > >> >> >> Kind regards, > > >> >> >> Wim > >> >> >> PA3DJSwww.tetech.nl > >> >> >> when you delete abc first, PM will reach me- Hide quoted text - > > >> >> >> - Show quoted text - > > >> >> >I have a question for you: > > >> >> >Do you believe that the characteristic impedance is dependent on the > >> >> >length of the coax? > >> >> >(For the ratio of transverse electric field to transverse magnetic > >> >> >field launched on a transmission line of infinite length.) > > >> >> "infinite length" <> "independent of length"- Hide quoted text - > > >> >> - Show quoted text - > > >> >Not sure I understand your cryptic post. > > >> >That is how characteristic impedance is classically defined, and I'm > >> >asking him if he believes that characteristic impedance is dependent > >> >on length? > > >> But you talk about dependency on length and "infinite" length in the same > >> paragraph. You can't have both variable length (which would include short) > >> and a dependency on being "infinite".- Hide quoted text - > > >> - Show quoted text - > > >OK - Maybe I could have stated that a little better.... (?) > > >My point: Does the length of the coax (or connector - since that's > >the topic of this post) have anything to do with characteristic > >impedance? > >And NOTE THAT THE DEFINITION OF CHARACTERISTIC IMPEDANCE ITSELF > >INCLUDES AN INFINITE LENGTH. (Which a connector DOES NOT have.) > > So you're asking if the characteristic impedance of a piece of coax varies > with length, when in the same question you define "characteristic impedance" > to be impedance (V/I) of an infinite length coax. Kinda silly to ask a > question when your question defines the answer, no? Are blue birds blue? > > >If I ask that question without mentioning that the various equations > >for characteristic impedance are derived from terms that include > >inductance per unit length (even if they later cancel out), then the > >question is absolutely meaningless. > > No, one assumes that the term "characteristic impedance" means something in a > group with the name sci.electronics.design. > > >So, I am PURPOSELY avoiding any possibility of a circular definition > >when I ask this question. > > No avoidance at all. Your question was self-circular. > > >Do you understand now? > > Why you asked the question the way you did? No, I have no idea. > > >Once you understand the question, we will look at whether or not the > >traditional equations for characteristic impedance are even valid > >(hint: I don't think they are!), given that they do not agree when > >applied to antennas, (which certainly have a length component). And, > >since they depend on antenna length, it contradicts the fundamental > >definitions. Even more interesting, the various calculations do not > >yield identical results, particularly if you consider an antenna to be > >a transmission line immersed in three-dimensional space. > > Perhaps the (simplified, btw) equations don't have enough terms to describe > every possibility that you think they should cover.- Hide quoted text - > > - Show quoted text - Honestly, I don't have the desire to get into a discussion/argument over semantics. The question is phrased correctly. The statement which follows it is also phrased correctly. I am traveling for a few days, so further thoughts will have to wait.... This may be too complicated a discussion for SED anyway. |