Coaxial cable velocity factor calculator 9/frequency in MHz) * velocity. We need to take this into account when we cut the wires for our dipole: A single layer of loosely woven braid versus a one or more dense layer(s) of braid and one or more layer(s) of metal foil versus semi-rigid versus hardline coaxial cable makes calculation using a simple, one-size-fits-all equation impossible. (Please pardon the simple decimal point error This page allows you to calculate the impedance required for a 1/4 wave (electrical) section of line. 7450 . c. Mathematically,!"= $ $-where!" is velocity factor Calculate the velocity factor of a coaxial cable used as a transmission line with the characteristic impedance of 50 ohms; capacitance is 40 pF/m and an inductance equal to 50 uH/m. Tags: none Coaxial Cable Calculator. The coax cable you are using might for example, have a velocity factor of 66%. Coaxial cable specifications often include the velocity factor, which is typically between 60% and 90% (1). 78) Velocity Factor: 66% (0. RG58A, RG58B, RG58C, RG213, RG214, and RG8 have a velocity factor of 0. applies See full list on translatorscafe. The Velocity Factor (VF) is a property of transmission lines, specifically used with coaxial cables. 0745 D. 66 on the calculator the antenna will be too short. 81) Velocity Factor: 78% (0. But to calculate the right length of each element, we need to know the Velocity Factor, or the signal speed through the cable compared to light traveling in a vacuum. 4” Minimum Bend Radius: 5” Recommended for Rotator Loops DXE-400MAX Low-Loss Cable This video shows some simple ways to measure the velocity factor (VF) and impedance of a known length of coax. we can calculate the line impedance, the delay in terms of time and phase, the speed of propagation and the velocity factor. Dec 3, 2024 · The calculator takes into account the frequency of the signal being transmitted, the velocity factor of the coaxial cable, and the speed of light to compute the maximum allowable distance for a reliable signal transmission. A transmission line (like coax) is a conduit for an electromagnetic wave in itself, so the velocity factor can be defined. The central conductor against the inside of the braid, with a low loss dielectric and well controlled impedance and velocity factor. 0745 n= 13. 9, 299. 85. A common thought of many is since this is coaxial cable, we need velocity factor adjustments. Coax Impedance Calculation. 7504 C. This slowing effect is almost entirely caused by the dielectric material—in coaxial cables, the insulation between the shield . Now we have dealt with coaxial cables, we should turn our attention to the various connectors and their losses. So let’s do the measurements. 84 and the feeder cable’s velocity factor is 0. All that aside now, lets calculate the ½ wavelength of RG58/U coaxial cable with a frequency of 444 Megahertz: ½ wavelength of coax The first step is to figure out the lengths of the various sections of the antenna. that means that in F2-F1 freq difference the signal made 360-0 degree phase shift difference (one period of phase shift change through the cable length) 4. com Nov 20, 2022 · With this calculator, you can calculate the length of a coaxial cable with the most common internal insulation materials, as well as the most commonly used quarter, half, or three-quarter wavelengths. 66 . 79. L. This is usually the distance to the fault in a cable. 12-22. If we go back to the two cable types discussed earlier, the headend cable’s velocity factor is 0. Velocity factor 0. Lowering the constant increases the velocity. Aug 1, 2023 · Variables: VF is the Velocity Factor ( ) k is the dielectric constant ; To calculate the velocity factor, divide 1 by the square root of the dielectric constant. A chart showing the VF of some of the more common 50 ohm cables is at the right. 2. To calculate the electrical length of the line you need to multiply the velocity factor of the line (available from the supplier of the line) by the free space length of 1/4 wave. Where: Zo = Characteristic impedance in Ω. A higher relative permittivity results in higher capacitance, which can slow down the signal transmission speed and affect the cable’s overall performance. Oct 3, 2024 · This calculator provides a simple and efficient way to determine the Velocity Factor, aiding students, engineers, and professionals in the field of RF communication and electromagnetic wave propagation. b. space. For a coax cable the velocity factor is 1/SQRT(ER), where ER is the dielectric constant of the dielectric fill. 42 What length of standard RG-8/U coaxial cable would required to obtain a 45° phase shift at 300 MHz? This gives a velocity factor of 0. This distance is influenced by factors such as the cable’s velocity factor, the frequency of the signal, and the inherent properties of the cable material. at frequency F2 the phase shift will be 360degree (because we count the phase mod 360) 3. Entering these various values will calculate the impedance of the coax cable using the formula below. 78, and 9913 cable has a velocity Oct 22, 2024 · Understanding Coax Velocity Factor Coaxial cables, commonly known as coax cables, are widely used in telecommunications, broadcasting, and data transmission. 7 ish (2/3 is often used for a rough figure). This modifies the wavelength equation: $$\lambda=\frac{\nu c}{f}$$ For example, the wave propagating along the conductor of a dipole antenna to produce radio waves encounters the interface between the conductor and free Velocity: Solid Polyethylene (PE) 1. This video provides a brief overview of the velocity factor and the two most common methods used to measure the velocity factor of coaxial cables. 66) Minimum Bend Radius: 6” Repeated BendsMinimum Bend Radius: Minimum Bend Radius: 2. Aug 8, 2024 · The relative permittivity of the material between the inner and outer conductors of a coaxial cable affects its capacitance and, consequently, its impedance and velocity of propagation. A common VF for hardline coaxial cable is 0. The Velocity Factor Calculator estimates the speed at which electromagnetic signals propagate through a medium based on the dielectric. Cut the coax to the suggested length plus a few inches, in case your velocity factor is not quite right. 27: Properties of Popular Coaxial Cables. 2) Velocity Factor of a Coaxial Cable. One critical aspect of coaxial cables that engineers and technicians must understand is the velocity factor. g. Aug 11, 2011 · Finding the Velocity Factor of Coaxial Cable. 7504 . Figure 3 highlights my reasoning… Calculate the velocity factor of a coaxial cable used as a transmission line, with the characteristic impedance of 50 ohms; capacitance is 40 pF/m, and inductance equal to 50 microH/m. It is called "velocity factor," or a speed of the radio wave propagation. Calculate the velocity factor of a coaxial cable used as a transmission line with the characteristic impedance of 50 ohms; capacitance is 40 pF/m and an inductance equal to 50 microH/m. a. 95 (95% the speed of light). Jul 22, 2019 · So, if the Propagation Velocity is 70%, it means that the signal in a cable will propagate at 0. If the dielectric constant of the cable (ε r) is known, the approximate velocity factor can be calculated using equation 5. 002 V. 5 with no velocity factor. Notice the resultant wavelengths. Stop frequency 1 GHz => Electrical cable length 120 m / 0. It’s just coincidence that you get good match with just the centre connected, there will be lots of RF on the feeder though. Line loss is the most important coax quality a radio amateur will care about. For more information, please see Wikipedia's article Velocity Factor. Next, we'll use the Microwaves101 coax spreadsheet to calculate the attenuation of these cables. 81) Velocity Factor: 82% (0. 129" is equal to The phase velocity at which electrical signals travel along a transmission line or other cable depends on the construction of the line. These numbers should look familiar by now This worksheet calculates wavelength (W. 257. Line loss explained. Generally, the higher the velocity factor, the lower the loss through a coaxial cable. FAQ’s. Delay time in an S21 measurement 174 m / 3e8 m/s = 580 ns! Now the important calculation for not getting phase shift differences of more than 360°! => Frequency step 1 / 580 ns = 1. Will add 0. Note that attenuation values are given at 400 Velocity Factor: 84% (0. 296 dB. Velocity Factor = FACT: RF slows down when traveling within coaxial cable. And of course, you can use our on-line coax calculator to solve for both of these coax parameters. υ (Velocity factor of transmission line) Note: The value of μr in this calculator has been taken as 1. 66 and LMR Another point of interest in designing antennas is that the velocity factor is different for various coax cables. Leaving one end of the coax open, set your RF analyzer to Mhz and trim the coax until you see minimum Z impedance (alternatively, you can also look for minimum X reactance). On occasion we find a length or roll of coax that’s in fairly good condition but with little to no information about its characteristics. Velocity factor is a property of electromagnetic wave propagation, not wire. You will need to know the velocity factor of the coax you are using to get this right. 82) Velocity Factor: 66% (0. 7450 B. Aug 7, 2010 · Each end of the outer shield of the stub is connected to the feed system. 4 V and reflected voltage E,. Oct 26, 2017 · I’m going to build a 12 element Collinear Antenna out of cheap RG-58 coax cable. 87. Cable length 120 m. References: 1. The velocity of propagation is inversely proportional to the dielectric constant. The coaxial cable is electrically charged and sometimes consists of different uninsulated conductors that remain entangled with one another. The value of 236. d. Simply put, RF slows down by the velocity factor when traveling through coaxial cable. Learn more abou Coax impedance equations are on this page, and a more accurate look is on this other page. It is expressed as a ratio or a If the "stuffing" in a coax cable is PTFE, with a dielectric constant (relative permittivity) of 2. You can use the Power Compensator to calculate dBW. 7, 494, and 983. solid conductors, velocity factor, and type of outer insulation. 69 = 174 m. 5” NOT Recommended for Rotator Loops Minimum Bend Radius: 2. and the center conductor. 66 is based on cheap and readily available RG58/U. Length of an impedance Coaxial Cable Calculator. Velocity Factor of Propagation Through Coaxial Cable The velocity factor is the speed at which an RF signal travels through a material compared to the speed the same signal travels through a vacuum. Velocity factor is a fractional value relating to a transmission line’s propagation speed to the speed of light in a vacuum. 0745 . Determine the reflection coefficient for a transmission line with incident voltage E; = 0. 0475 Nov 7, 2020 · Although not a coaxial cable, most references list a characteristic impedance of about 100 ohms and velocity factor at about 0. Jul 21, 2020 · My understanding: 1. This slowing effect is almost entirely caused by the dielectric material; in coaxial cables, the insulation between the shield and the center conductor. Oct 30, 2010 · The most straight forward method of calculating the electrical length of a piece of coax involves first calculating the free space wavelength of the target frequency and multiplying by the velocity factor of the coax. Q: What is coaxial cable attenuation? A: Coaxial cable attenuation refers to the reduction in signal strength as it travels along the cable due to factors such as resistance, dielectric losses, and Velocity factor is the proportion of c (speed of light) that a signal travels at in a cable: - VF = \$\dfrac{1}{c\sqrt{LC}}\$ Where L and C are the distributed inductance and capacitance per metre length of the cable. The velocity factor (VF), also known as wave propagation speed or velocity of propagation, is a measure of the speed at which an electromagnetic wave travels through a medium compared to the speed of light in a vacuum. Register to edit. In the first type of mismatch, the cable impedance is slightly mismatched from 50 ohms. A coaxial cable is actually two transmission lines with different dielectric, impedance and velocity factors. Professional coax starts at 0. Background. So along with the cable diameter, the velocity factor of a cable is in fact a fairly good indication of the cable loss (keeping all other things constant). The Velocity factor or Propagation Velocity of a cable can be calculated by the formula below (where ϵ is the dielectric constant of the dielectric material used in the cable). we calculate the length of ½ wavelength in free space we need to adjust its size by multiplying it by the velocity factory. 12 nH/m, determine the velocity factor and velocity of propagation. A. Mar 1, 2010 · A little number crunching with the latter equation and the ratio that defines index of refraction gives us 1/√ε r = velocity factor. It is possible to measure the velocity factor of a transmission line using the voltage output of the V/C Detector to detect phase cancellation. 3. 07, the velocity factor is 69. You now have a length of 71 degrees at your desired operating Feedpoint impedance and coaxial matching section. Velocity Factor: 84% (0. εr = Relative Our coaxial cable impedance calculator allows you to enter the outer diameter dielectric width, Inner conductor diameter width and either the dielectric constant or velocity of propagation (VoP) values. 80 for typical two-wire lines and coaxial cables. Answer: Vf = 0. Feb 1, 2024 · Velocity Factor: 0. This article will explore what the velocity factor is, how it affects signal transmission, and its significance in coaxial How to measure the velocity factor of a piece of coax using a VNA. This video provides a brief overview of velocity factor and the two most common methods used to measure the velocity factor of coaxial cables. For a closed-cell foam dielectric, for This coaxial cable calculator determines the distributed capacitance and inductance of a coaxial cable, its impedance and cutoff frequency for a given cable geometry, and relative permittivity or velocity factor. Understanding VF helps in designing efficient communication systems, ensuring accurate wavelength and impedance matching. Values range between 0. 7 times the speed of a signal if the dielectric of the cable was vacuum. that is "equivalent" to say "at F1 The relative propagation velocity is defined as follows. Our wavelength calculator tool uses the given frequency and dielectric constant/velocity of propagation (VoP) of the RF input signal. Little "c" is the speed of light. In electrical cables, the velocity factor mainly depends on the insulating material. For any cable type, it is equal to the reciprocal (1/x) of the square root of the relative permittivity of the cable’s insulation. radio) passes through a medium. 05m (5cm) to compensate for the length of two pl259 connectors on ea The importance of knowing velocity factor and how to calculate it lies in the fact that radio frequency energy (RF) travels slower in wire/cable than it does in free space (air). Aug 8, 2018 · For optical signals, the velocity factor is the reciprocal of the refractive index. For the length in feet, this is (245. Calculates the velocity factor of transmission line and the round trip time of the pulse to get the distance of the reflection Apr 20, 2024 · Coaxial cable typically has a velocity factor around 0. Mar 8, 2023 · And the key thing is that when the effective quantity of dielectric is reduced, the velocity factor is also increased. The Velocity of Propagation calculator computes the speed of signal transmission through a medium relative to the speed of light in a vacuum. 54: 0. The impedance of the RF coaxial cable depends on the dielectric constant of the cable and the diameter of the inner and outer conductors. Therefore, the wavelength corresponding to a given frequency varies in different types of lines, thus at a given frequency different conductors of the same physical length can have different electrical lengths. Said another way, Velocity of Propagation (VP) or velocity factor (VF) is a parameter that characterizes the speed at which an electrical signal (e. A Velocity Factor can be applied if you are working with coaxial cables. One viewer rightly pointed out that I misspoke at 19:30. 69. Coax velocity factor of popular coax cable types is published in many places. :. Case 1. such as coaxial cables and Aug 8, 2024 · What is Coax Cable Distance? Coax cable distance refers to the maximum length over which a coaxial cable can effectively transmit a signal without significant loss or degradation. RG58 foam coax has a velocity factor of 0. I have measured up the physical length of this coaxial cable to be 3. We measured the following data (hp8753) . 96 I included it for use with insulated wire as elements. Calculate the overall length of the antenna using the formula: Apr 10, 2016 · Coax cable properties that radio amateurs should consider are line loss, shielding, stranded vs. 659c: Foam Polyethylene (FE) 1. v c l r l o e = ⋅ = ⋅ u j 100 100 in % (20) u j - propagation velocity in cable c o - propagation velocity in free space (300⋅ 103 km / s) l - geometrical length in m l e - electrical length in m Delay is defined as follows: t v r v r c o j = = ⋅ 333,6 108 in ns/m (21) v r Fairview Microwave's Coaxial Cable Impedance Calculator allows you to enter the Outer Diameter Dielectric width, Inner conductor Diameter width and either the Dielectric Constant or Velocity of Propagation (VoP) values in order to calculate the impedance of the coax. On occasion we find a length or roll of coax that’s in fairly good condition but with little to no information about The velocity factor (VF), [1] also called wave propagation (relative) speed or (relative) velocity of propagation (VoP or ), [2] of a transmission medium is the ratio of the speed at which a wavefront (of an electromagnetic signal, a radio signal, a light pulse in an optical fibre or a change of the electrical voltage on a copper wire) passes through the medium, to the speed of light in vacuum. at frequency F1 the phase shift will be 0degree (because we decided so, it is the start) 2. TIME DOMAIN REFLECTOMETRY (TDR) LENGTH CALCULATOR. For copper tubing, leave it at 0. Velocity of propagation is velocity factor expressed as a The Pasternack wavelength calculator Transverse Electromagnetic Mode (TEM) allows you to determine the wavelength (in millimeters) inside a rectangular waveguide. light is known as the velocity factor, or Velocity of Propagation (VOP), expressed as a percentage of the speed of light in free . 66) Minimum Bend Radius: 2. For a closed-cell foam dielectric, for You can use the Power Compensator to calculate dBW. ), half wavelength and quarter wavelength of coaxial cable based on the velocity factor of said cable at a frequency of interest. Things to notice: try frequencies 149. Velocity Factor of a Transmission Line. 18 degrees Calculate the velocity factor of a coaxial cable used as a transmission line, with the characteristic impedance of 50 ohms, capacitance is 40 pF/m, and inductance equal to 50 μH/m. Feb 2, 2025 · The Velocity Factor Calculator provides a quick way to determine signal speed in transmission lines. Coaxial Cable Calculator. The Cable 229. Cables with 82% VF (foam PE) will have about half the loss per length 1. 9914 cable has a velocity factor of 0. In fact, the velocity factor can be derived from the lumped model of a transmission line: simulate this circuit – Schematic created using CircuitLab Velocity Factor and Velocity of Propagation Velocity factor is the ratio – in decimal form – of the speed of an electromagnetic signal propagating through coaxial cable to the speed of light in a vacuum. 5%. 65. The insulating Amateur Extra question pool, Subelement E9, Section E9F: Transmission lines: characteristics of open and shorted feed lines; 1/8 wavelength; 1/4 wavelength; 1/2 wavelength; feed lines: coax versus open-wire; velocity factor; electrical length; coaxial cable dielectrics; velocity factor The used Coaxial cable was KOKA 99 HD Plus (75 ± 3 Ω) with a Velocity factor of 83 ± 1 %. If the radiating elements are made from bare copper copper wire, the velocity factor is around 0. Enter the Frequency to be converted; Select the Frequency value's Dimension; Select whether a Velocity Factor. 38 284. Like light, radio waves travel at the speed of light in a vacuum. Otherwise, check out the dielectric constant of the material used in your coaxial cable and type it into the J-pole antenna calculator using the Additional parameters field. The velocity factor on the calculator is for the J-pole itself, if you used 0. The velocity factor, $\nu$, represents this slowing and is less than one (except in free space, where it is exactly one). The inductive component has an additional component at the lower frequencies which slows the signal somewhat. Tags : Coaxial Cable Share this Video: Apr 9, 2023 · Characteristic Impedance Calculator. The default of 0. 91 and higher, so check the specifications of your coaxial cable from the manufacturer before cutting your segments and remember to add some extra length of the center core conductors for good cross segment connections! light is known as the velocity factor, or Velocity of Propagation (VOP), expressed as a percentage of the speed of light in free . Use is pretty straight forward. The feedpoint impedance at the design frequency is about 100 ohms, so full wave loops are often fed with an impedance-matching section made from a piece of 75-ohm coxial cable one quarter wavelength long (shortened to compensate for the velocity factor of the cable). 55m2. 12-23. 1. This coaxial cable calculator determines the distributed capacitance and inductance of a coaxial cable, its impedance and cutoff frequency for a given cable geometry, and relative permittivity or velocity factor. Coax cut-off frequency equations are available on this page. The ratio of actual speed to the speed of light is known as the velocity factor, or Velocity of Propagation (VOP), expressed as a percentage of the speed of light in free space. 84) Velocity Factor: 81% (0. Two types of mismatch cause the same effect, we'll describe both types below. Since the electric and magnetic fields (of the stub system) are in air, I think velocity factor does not apply. 7 MHz – we use 1 MHz. This indicates that the electrical length is actually 66 percent of the free space length! Be sure to figure this into your calculations. Last edited by markadlerdallas. Does anyone have tips for using a nanovna calibrated for 50 ohms to measure such twisted pair cable? Mar 24, 2025 · The Coax Cable Distance Calculator is a valuable tool for engineers and hobbyists working with RF and communication systems. For a given length of coaxial cable with distributed capacitance C = 24. The speed factor of the cable is an important parameter, so you can always find it in the data sheets of the coaxial feeder. The term we use to indicate how much a conductor slows down the propagation of rf is Velocity Factor, often written as VF. = 0. Also, see Electronics Notes site for the article Coax Cable Velocity Factor. You can use \$\epsilon_R\$ as well because \$\mu_R\$ can be assumed to be unity: - Feb 11, 2021 · (Sources: Belden Catalog, Times Microwave LMR catalog; Davis RF web site; ERI catalog) Enter the velocity factor of transmission line and the round trip time of the pulse to get the distance of the reflection i. This calculator is used to convert Frequency to Wavelength. The amount it is slowed down is the velocity factor (V f) of the signal transmission, sometimes referred to as the velocity of propagation. The velocity factor for RG8X is 0. May 8, 2021 · A Note about Velocity Factor. Apr 9, 2023 · 5. 4” Minimum Bend Radius: 5” 2. A coaxial cable, in general, consists of an inner conductor that is surrounded by a spacer. 66 and 0. Sweep points 1 GHz / 1 MHz What is the velocity factor of coaxial cable with a characteristic impedance of 50 Ω and capacitance of 30 pF/ft and inductance of 75 nH/ft? Calculate the angle Oct 14, 2021 · A channel is a circuit, so it must have a return path. The impedance can be calculated by the following formula. Velocity of light for quasi-TEM transmission lines such as microstrip and coplanar waveguide is equal to the speed of light divided by the square root of the effective relative permittivity. 15 pF/m and distrib­ uted inductance L = 483. 0. By inputting the correct velocity factor, frequency, and speed of light, users can accurately determine signal wavelength, ensuring optimal cable performance. S11, Sum Port was 30 dB @ 158 MHz S22, Port 1 was 22 dB @ 158 MHz. The importance of knowing velocity factor and how to calculate it lies in the fact that radio frequency energy (RF) travels slower in wire/cable than it does in free space (air). Two come to mind: RG58 has a Vf of 0. If the dielectric constant (e r)of the cable is know rather than the velocity factor (v f), that parameter may be entered instead. Equation 5. e TDR Length. 8 and 468 with 95% end effect factor. This occurs around 100 KHz for small coax and lower for larger cables. About Press Copyright Contact us Creators Advertise Developers Terms Privacy Policy & Safety How YouTube works Test new features NFL Sunday Ticket Press Copyright RG-58 is a coaxial cable that is used for wiring purposes. 0475 Coaxial Cable Calculator. Just enter any power in watts and the calculator will convert it to dBW. Try 142. 66; Cable Length: 1000 feet; Plugging these values into the calculator, we get an attenuation of approximately 1. 5” Fixed Install Recommended for Rotator Loops DXE-400MAX Low-Loss Cable DXE-8U Low-Loss Foam Dielectric Cable Feb 25, 2019 · The signal velocity is slowed when travelling over a dielectric material. You can use the Coaxial Length Calculator for any cable that is not shown in the table providing you know the velocity factor and loss per 100m at any frequency you wish to use. This calculator can also be used for measuring coaxial cable and will then give Relative Dielectric Constant rather than Effective Dielectric Constant. Jul 27, 2015 · You can use the Coaxial Length Calculator for any cable that is not shown in the table providing you know the velocity factor and loss per 100m at any frequency you wish to use. The speed of radio signals in a vacuum, for example, is the speed of light, and so the velocity factor of a radio wave in a vacuum is unity, or 100%. 535. Calculates Delay, Velocity Factor, Effective Dielectric Constant and Characteristic Impedance of a PCB track. Since any dielectric permittivity greater than 1 (air/vacuum) will have the effect of slowing the phase velocity of a wave, the VF is given as a percentage representing that reduced phase velocity. 87, and for drop cable is 0. dqcurfr tvl ihljgmz rnmzmqk sbcqhxsu avtm ceuumd shijr qzrp cgr vggh oyqo feptmnx lmyhytcr tljkyi