low MHz connector design consultant
in [Design]
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From: Baron on 1 May 2010 16:19 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)) -- Best Regards: Baron.
From: Baron on 1 May 2010 16:27 mpm Inscribed thus: > 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.) > 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. > > So, I am PURPOSELY avoiding any possibility of a circular definition > when I ask this question. > Do you understand now? > > 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. Considering that an antenna can be looked at from the point of view that it is a transformer coupling energy to or from the ether that is frequency dependant I might agree. -- Best Regards: Baron.
From: tm on 1 May 2010 16:33 "Baron" <baron.nospam(a)linuxmaniac.nospam.net> wrote in message news:hri2ce$910$1(a)news.eternal-september.org... > mpm Inscribed thus: > >> On Apr 30, 10:58 pm, "k...(a)att.bizzzzzzzzzzzz" > > 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)) > It also assumes a match at both ends of the line. Tom
From: Baron on 1 May 2010 16:48 tm Inscribed thus: > > "Baron" <baron.nospam(a)linuxmaniac.nospam.net> wrote in message > news:hri2ce$910$1(a)news.eternal-september.org... >> mpm Inscribed thus: >> >>> On Apr 30, 10:58 pm, "k...(a)att.bizzzzzzzzzzzz" >> >> For co-axial cables its a function of the ratio of the diameters of >> the conductors modified by the dielectric constant of the insulator, >> or for twin conductor the spacing between them and the dielectric >> constant of the insulator. >> ie (impedance = (138 / e^(1/2)) * log (D/d)) >> > > > It also assumes a match at both ends of the line. > > > Tom ??? -- Best Regards: Baron.
From: tm on 1 May 2010 17:43
"Baron" <baron.nospam(a)linuxmaniac.nospam.net> wrote in message news:hri41l$ple$2(a)news.eternal-september.org... > tm Inscribed thus: > >> >> "Baron" <baron.nospam(a)linuxmaniac.nospam.net> wrote in message >> news:hri2ce$910$1(a)news.eternal-september.org... >>> mpm Inscribed thus: >>> >>>> On Apr 30, 10:58 pm, "k...(a)att.bizzzzzzzzzzzz" >>> >>> 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)) >>> >> >> >> It also assumes a match at both ends of the line. >> >> >> Tom > > ??? Sure. Take a piece of coax, any impedance, 1/4 wavelength long, and short one end. What do you see at the other end? Now match both ends. What impedance do you see at any point of the line? Tom |