Coaxial Definition and 176 Threads

  1. M

    Coronal Mass Ejection = Buzzing Coaxial Outlet?

    Hello all. Let me start with my main question and then provide a bit more background. I just noticed that an unused coaxial cable outlet in my apartment is periodically producing a faint but very noticeable buzzing sound. It seems to come and go, flickering on and off sometimes and...
  2. B

    Question about coaxial digital to analog converters

    Is there a coaxial digital to analog converter that only decodes the digital signal into multiple signals for the channels and then converts the digital signals into analog signals but does not serve as a digital tuner? Because most coaxial digital to analog converters do not decode the...
  3. S

    Impedance Matching for "Electrically Short" Coaxial Lines at 125 MHz

    Hey all, Between two devices, I will need to have a coaxial line (with SMA connections on either end) connecting them. The operating frequency of the signal I am propagating is approximately 125 MHz. With this said, the wavelength (assuming ideal) is 2.4 meters. I have heard from numerous...
  4. K

    Coaxial Cable ( Transmission line )

    How does current flow in a coaxial cable in each of the following cases : 1. When the cable is connected to a DC voltage source. 2. When the cable is connected to an AC voltage source 3. When the outer metallic shield is connected to ground and DC and Ac sources are connected separately I...
  5. S

    Modeling coaxial cable impedance

    Hi, I am trying to model electrical equivalent of a coaxial cable. The data I have is 1. Conductor resistance 2. Insulator resistance 3. Partial discharge 4. Insulation Thickness 5. Overall diameter Actually I planned to use an equivalent circuit that has series connection of...
  6. J

    Calculating Reflection Coefficient in Coaxial Cable with Annular Sheet

    Homework Statement An annular sheet, of thickness t=1mm and resistivity ρ=0.5Ωm, connects the inner and outer conductors of an air spaced coaxial transmission line at a point on the line. A low-frequency signal is fed into one end of the line and the other is terminated by its characteristic...
  7. T

    Electric Flux Density for Coaxial Cable

    Homework Statement I am given the following problem: http://forum.allaboutcircuits.com/attachment.php?attachmentid=35938&d=1320027350 Homework Equations The Attempt at a Solution My known equations and attempt to the problem...
  8. E

    What is the Electric Field Between Two Charged Surfaces?

    Homework Statement Hi, I'm having issues with a question about a coaxial cable. This is the question: A coaxial cable consists of a long straight cylindrical wire of radius R1, surrounded by a coaxial cylindrical shell of radius R2. For a situation where the inner cylinder carries...
  9. V

    How Is Charge Density Calculated in Coaxial Cables?

    Homework Statement I have attached the question as a pdf. Homework Equations I'm thinking that we take the line integral of voltage to get electric field. But I'm not sure how to proceed from here. Is the line integral from a to b? Also, how do I get the charge density having found...
  10. S

    Why aren't speaker cables Coaxial?

    Just out of interest I was wondering and couldn't work out... Why are (even high-end) speaker cables not coaxial? We always use a coaxial cable in the lab to get rid of the noise on our measurements. I figure that 50/75 ohm standard coax would create an impedance mismatch with the typically...
  11. A

    Radial resistance of coaxial cable

    One of the textbooks I've stumbled across states that the radial resistance of a coaxial cable ( current running from inner cylinder to outer cylinder via silicon in between) is given byR = [resistivity * natural log of (b/a)] / [2*pi()*(length of cable)] where b is the outer radii and a is the...
  12. C

    How does a coaxial transmission line work?

    On a coaxial transmission line is there AC current running through the center wire? And this AC current produces EM radiation that bounces down the wave guide. So is the purpose of this transmission line to send the signal via radio waves. And is this how cable tv works, are radio waves being...
  13. A

    Magnetic field in coaxial cables

    I think I solved this problem correctly, I just want to check because it's an interesting problem, and it's from a past exam. Homework Statement A coaxial cable consists of an inner solid conductor of radius r_1, and and outer conducting cylindrical shell of inner radius r_2 and outer...
  14. K

    Single Rotor Versus Coaxial Rotor Lift

    I'm having a tiny debate with someone over whether a 2nd coaxial rotor generates additional lift for a helicopter by itself or the helicopter has additional lift only due to the elimination of the tail rotor so 100% power goes to generating lift? My theory is that it does not generate...
  15. M

    How to Determine Charge Distribution in a Coaxial Cable?

    Homework Statement A long coaxial cable consists of an inner cylindrical conductor with radius a and an outer coaxial cylinder with inner radius b and outer radius c. The outer cylinder is mounted on insulating supports and has no net charge. The inner cylinder has a uniform positive charge per...
  16. S

    Magnetic field inside coaxial conductor

    Homework Statement The problem asks us to find the magnetic field inside a coaxial conductor that consists of an aluminum wire of radius r1 surrounded by a cylindrical aluminum shell of inner radius r2 and outer radius r3. I know how to do this, but it also says that there is oil flowing...
  17. 0

    Magnetic Forces in and around a coaxial cable

    Homework Statement So I'm doing a problem set and the question refers to a coaxial cable, I am told that the cable consists of an inner solid cable radius (R1), which is surrounded by a outer thin tube with radius (R2) , both have the same current though them but opposite direction. I have to...
  18. B

    Calculating Self-Inductance in Coaxial Cables

    Homework Statement A coaxial cable is made from concentric cylindrical conductors. The radius of the inner conductor is a and the outer comductor has inner radius b and outer radius d. Calculate the self inductance per unit length of the cable. You may assume that (b-a) >> a and (b-a) >>...
  19. P

    Ohm's Law: Coaxial Cylinder Resistance & Density

    Homework Statement Consider two coaxial conducting cylinders with radii a and 3a and length L. The region a<r<2a is filled with a material of conductivity σ1, and the region 2a<r<3a has conductivity σ2. (Assume ε1=ε2=εo.) The inner cylinder is held at potential V0 and the outer cylinder at...
  20. S

    Electric field from a rotating coaxial ring

    Homework Statement A wire with uniform charge density λ per unit length is bent into a ring of radius a and rotates with angular velocity ω about an axis through its centre and perpendicular to the plane of the ring. Find the magnetic field on the axis at a distance z from the ring...
  21. K

    How Does Gauss' Law Apply to Coaxial Cable Charge Distribution?

    Homework Statement A high voltage coaxial cable is used to supply power to an x-ray generator. The cable consists of an inner wire of radius r=1 mm and a thin hollow outer conductor of radius R= 10 mm. The inner wire and the outer shield have the same charge density per unit length of ...
  22. C

    How Does Charge Distribution Affect Electric Fields in a Coaxial Cable?

    1. A long coaxial cable consists of an inner cylindrical conductor with radius "a" and an outer coaxial cylinder with inner radius "b" and outer radius "c." The outer cylinder is mounded on insulating supports and has no net charge. The inner cylinder has a positive charge per unit length λ...
  23. P

    Need help finding the electric fields in a coaxial cable with charged conductors

    Homework Statement A coaxial cable consists of a long solid inner cylindrical conductor, radius a, and a thin outer cylindrical conductor of average radius b>a. Suppose the inner conductor has a line charge density of +lambda while the outer conductor has a uniformly distributed charge of...
  24. R

    Coaxial cable problem, electric field strength?

    Homework Statement A coaxial cable has an inner core diameter 6mm and inner diameter of the outer sheath is 20mm. There are two layers of insulation between the conductors, the inner layer from a radius of 3mm to 9mm has relative permittivity of 8 while the outer layer from radius 9mm to...
  25. Q

    Charged coaxial cable - Charge distribution?

    Homework Statement Say we have an infinitely long wire with radius r1 with a linear charge density +u and we have a coaxial conducting cylinder with radius r2->r3 and a linear charge density of +2u. http://img573.imageshack.us/img573/3419/coaxialcable.png" Now the overall aim of the...
  26. N

    Energy of Coaxial Cylindrical Shells

    Homework Statement Calculate the energy per unit length for two long coaxial cylindrical shells, neglecting end effects. The inner and outer cylinders have radii a and b, and linear charge densities λ and -λ, uniformly distributed on the surface, respectively. 2. The attempt at a solution...
  27. C

    Electric Field outside a Coaxial Cable

    Homework Statement Consider an 8mm diameter coaxial cable, which consists of a central conducting wire, and an outer cylindrical conducting braid. If a charge of +30mC is placed on the inner conductor, and a charge of -30mC is placed on the outer conducting braid, what will the electric field...
  28. D

    How to Determine the Electric Potential Difference in a Coaxial Cable?

    Physics 2 coaxial potential help! https://wug-s.physics.uiuc.edu/cgi/courses/shell/common/showme.pl?cc/DuPage/phys2112/summer/homework/Ch-22-E-Potential/IE_cylindersV/coax.gif The diagram above shows a coaxial cable. The inner conductor has radius a = 0.0025 m. The outer conductor is a...
  29. C

    About current/voltage reflection in a long coaxial wire.

    If I have a long coaxial wire with open end and apply a short voltage pulse, that pulse begins propagating through it until it reaches the end. Then, it reflects back to where it came from. I understand that it behaves like a normal wave, maintaining its energy and bouncing when it reaches a...
  30. M

    Magnetic Field Between Coaxial Cylinders

    Homework Statement Two long thin concentric perfectly conducting cylindrical shells of radii a and b (a<b) are connected together at one end by a resistor of resistance R, and at the other by a battery that establishes a potential difference V. Thus, a current I=V/R flows in opposite...
  31. T

    What is the Electric Field at 2.6 mm from the Axis of Coaxial Cylinders?

    [b]1. Charge of uniform density 76nC/m^3 is distributed throughout a hollow cylindrical region formed by two coaxial cylindrical surfaces of radii 1.5 mm and 3.7 mm. Determine the magnitude of the electric field at a point which is 2.6 mm from the symmetry axis. I tried...
  32. S

    Coaxial cable with unequal currents

    1. Homework Statement I just have a question concerning an unbalanced coaxial cable. By unbalanced, I mean that the inner and outer currents are not equal magnitudes of the opposite direction of each other. My homework problem has an inner current of +100[mA] and an outer current of 90[mA] in...
  33. I

    Simple calculation of the self inductance of two coaxial solenoids in series?

    Hi all, The situation is this: I need to calculate the self inductance of two solenoids wired in series, of equal radius and a given separation d. They are coaxial. The length h of each is known. Most double-solenoid references I found looked at the mutual inductance, and not the...
  34. R

    Is Free Charge Density Possible in a Dielectric with Zero Potential Conductors?

    Homework Statement If I have two co axial conductors at V = 0 and the dielectric has a free charge density. Is that physically possible? Homework Equations No relevant equations The Attempt at a Solution I am not sure if you can have free charge density in a dielelctric when both conductors...
  35. M

    What Initial Current Flows When S is Closed in a P241B Coaxial Cable Circuit?

    Homework Statement Type P241B coaxial cable has an inductance of 0.4 μH/m and a capacitance of 40 pF/m. The diagram below shows a 100 m length of this cable connected to a battery and switch at the sending end and a 50Ω resistor at the receiving end. (a) If S is closed, what initial current...
  36. R

    Electric Field in a cylindrical Coaxial Capacitor

    Homework Statement Two infinite coaxial metal cylindrical tubes of radius a and b (a < b) are charged with charge per unit length (unit [C/m]) \lambda and -\lambda respectively. Calculate the electric field between the tubes (i.e. for a < r < b) Where \epsilon_{0} is the permittivity...
  37. S

    Polarization of Coaxial Cable with Compound Dielectric

    Homework Statement A coaxial cable of circular cross section has a compound dielectric. The inner conductor has an outside radius a , which is surrounded by a dielectric sheath of dielectric constant K_1 and of outer radius b . Next comes another dielectric sheath of dielectric constant...
  38. G

    The Magnetic Field of Coaxial Cables

    Homework Statement A coaxial cable of length l, has a thin wall cylindrical inner conductor of radius a carrying current I. All current returns along the outer conductor whose inner radius is b. Assuming that the current flows only in a thin layer on each conductor, determine the magnitude...
  39. R

    What is the Attempt at a Solution?

    Homework Statement If the outer conductor of a coaxial cable has radius 3.5 , what should be the radius of the inner conductor so that the inductance per unit length does not exceed 55 per meter? Homework Equations The Attempt at a Solution 1.385
  40. B

    Capacitance of three coaxial metal tubes

    Homework Statement Find the capacitance per unit length of three long coaxial metal tubes, with radii a < b < c . A wire connects the innermost and outermost tubes (radii a and c). Homework Equations The Attempt at a Solution I'm a little confused as to how I should set this...
  41. L

    Cavity Resonators by two waveguide coaxial adapters

    One of my professors made an X-band cavity resonator by putting together, end to end, two X281A coaxial waveguide adapters (n-type) with cut center pins. It works pretty well - but I need some more information. Does anyone know where can I find some more information on this setup...
  42. H

    Can Coaxial Wires be Converted to DC for LED Power?

    Hi Guys, For my design project, I am dealing with a horn antenna that has coaxial wire for the input and output. The problem is, I need to take the signal recived from the antenna by the coaxil and feed it to another circuit, since I need to us a circuit to down convert the freqeuncy or...
  43. B

    Charge inside and outside coaxial cable

    I'm attempting to teach myself some electrostatics, so that I'll be prepared when I head back to school full time. Homework Statement Determine the electric field inside the inner conductor, between the conductors, and outside the conductors of a coaxial cable when the inner conductor is...
  44. D

    Resonant Frequencies of Coaxial Cylinders

    Does anyone know of a formula for determining the various resonant frequencies of 2 coaxial cylinders with radius a and b and height h? Thanks.
  45. C

    How Do Impedance Minima Relate to Coaxial Cable's Speed of Propagation?

    I know my impedance minima and their associated frequencies for a particular coaxial cable. How would I go about deriving an equation that will let me calculate the speed of propagation and the dielectric constant? My only hint is to consider the case for which Z = 0 but I don't know where to...
  46. D

    Magnetic and electric field between current carrying coaxial cables

    Homework Statement Two long concentric, cylindrical conductors of radii a and b (a<b), are maintained with a potential difference V and carry equal but opposite currents I. An electron, with velocity u parallel to the axis, enters the evacuated region between the conductors and travels...
  47. L

    Where Do the Factors c^2 and ab Originate in the Coaxial Cable Integral?

    http://img154.imageshack.us/img154/165/integrallll.jpg After working it out myself, I have the logarithim part equal to: [ln b - lna] + [ln c - ln b] = [ln b/a + ln c/b] = ln c/a (Not sure about this statement!) I don't understand where the c^2 and ab came from with this integral...
  48. T

    Heat exchanger consisting of Coaxial Cables

    Homework Statement A heat exchanger consists of two straight co-axial tubes, each of square cross-section. Liquid 1 enters at a rate m1 kg.s-1 at one end (x = 0) of the exchanger at temperature T10, and flows through the inner tube. Liquid 2 emerges at a rate m2 kg.s-1 at x = 0 at...
  49. S

    Electric field and potential difference in coaxial cable

    Consider a coaxial cable with inner radius a and outer radius b. The potential difference between the inner and outer conducter is V. How can it be shown that the electric field at a distance r from the inner conducter is given by: E = \frac{V}{r ln\frac{b}{a}} Any help would be much...
  50. N

    Waves in a coaxial cable: Boundary conditions

    Homework Statement Hi all. I have the following expression, which relates the incoming amplitude with the reflected amplitude at a point x = L in a coaxial cable: A_{\text{reflected}} = \frac{R-Z_0}{R+Z_0}A_{\text{incoming}}. Here R is the resistance at the point x = L and Z0 is the...
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