Velocity factor insulated wire. Moxgen DOES NOT allow for insulated wire.

Velocity factor insulated wire. With ordinary antenna wire insulated up to twice the wire diameter with PVC, the reduction in velocity from the speed of light is insignificant and pruning can be forgotten about. The velocity of propagation is inversely proportional to the dielectric constant. 14 AWG 7 Strands: Bare Hard Drawn Copper Wire; 14 AWG 7 Strands Bare Stranded Copper Clad Steel Wire; Davis RF - FLEX-Weave TM. Alternatively, use a 1/0. Values range between 0. A single conductor doesn’t have this distributed inductance and capacitance—at least not to the extent that it would cause a 5% change in the velocity factor. 659. 3 for the insulation and perfect ground was assumed. An alternating electric current of a single frequency is an oscillating sine wave which repeats with a period of = /. In table 4 the length of the vertical (wire 1) was constant at 134'. . While having a higher velocity factor is not really such a big advantage, open-wire or ladder line feedlines do have other advantages. This is a pity, because Estimate the velocity factor F = v/c and the impedance Z of a two-wire transmission line made of cylindrical conductors of radius a whose centers are separated by distance d, when each wire The dielectric constant of normal wire insulation (polyethylene) is about 2. It's expressed as a fraction or percentage of the speed of light. 82) Velocity Factor: 66% (0. 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%. I've built J-poles before for 3 metres (back in my pirate days), but never with twinlead. 12 AWG Bare Annealed Copper Stranded Flex-Weave; 12 AWG Bare Tinned Annealed Copper Stranded Flex-Weave; 12 AWG Black PE Insulated Can I measure the velocity factor directly? The velocity factor is typically calculated rather than directly measured, as it depends on material properties. As a consequence, the insulated-wire velocity-factor graph (Fig. How do I convert velocity factor to time delay? Time delay can be calculated using the length of the transmission line and the velocity factor. Highly UV resistant PVC jackets of clear, black, and camouflage green are also stocked as well as bare wire. 4) remains usable for the entire set of loss-tangent values covered by the exercise. And you forgot to take into consideration the velocity factor of the wire (which is abt 0. I got this figure some time ago here on TT. For a closed-cell foam dielectric, for Velocity Factor] The most prevalent wire & cable insulation materials ap-proved and generally acceptable for aircraft are from the Teflon® family—a familiar brand name for fluoropolymers which include, for example, PTFE, ETFE (also known as Tef-zel®), TFE, and FEP. This wire is readily available at hardware and home improvement Electromagnetic waves propagate more slowly in materials or at boundaries. 83, meaning that electromagnetic waves travel at 83% the speed of light in a vacuum. This slowing effect is almost entirely caused by the Estimate the velocity factor F = v/c and the impedance Z of a two-wire transmission line made of cylindrical conductors of radius a whose centers are separated by distance d, when each wire By comparing, for example, the resonant length of a bare wire and a wire with a given type and thickness of insulation, we can obtain the velocity factor of the insulated wire in antenna (not in In electrical cables, the velocity factor mainly depends on the insulating material (see table below). 12 AWG FLEX-Weave Antenna Wire. When used as an antenna, the current travels in the same direction on both If you are using insulated wire you need to decrease the dimensions by roughly 4% as due to the velocity factor of insulated wire, it appears 4% longer to RF. 84) Velocity Factor: 81% (0. typically not insulated so in this example I looked at three cases: all bare wire, all insulated wire and insulated radials only. Signals in a coaxial cable travel as transverse electromagnetic waves with currents in the copper and electric fields [See The Velocity Factor] The most prevalent wire & cable insulation materials approved and generally acceptable for aircraft are from the Teflon® family — a familiar brand name for Electromagnetic waves traveling on transmission lines such as 300 ohm twin lead travel more slowly than they do in free space. 73 de Gene Smar AD3F ----- Original Message ----- From: "Bill Tippett" <btippett@alum. Variables are the diameter of the wire and it's proximity to ground or other conductors. 54: Teflon (TFE gauge conductors consisting of 19 strands of copper-clad steel wire. We are all familiar with how adding insulation to a bare copper wire decreases the velocity factor, resulting in the need to shorten the wire about 1 or 2% (depending on he insulation material). 5. The use of the terms velocity of propagation and wave propagation speed to mean a ratio of For common conducting metals the difference between two metals is very small and is generally swamped by other things that affect velocity factor, such as insulation. A single conductive element – even one wrapped around or FLEX-WEAVE TM comes in #14 (168 strands of #36 wire) or #12(259 strands of #36 wire). For example, ladder line has lower loss than small-diameter c = velocity of light ( 299,792,458 m/s ) f = centre frequency of the antenna in Hz vf1 = velocity factor of coated wire (I use 0. 2 Unit-per-length inductance L′ and capacitance C′ of a single PVC insulated wire above an infinite ground plane. Simulating insulated wires with NEC-2. 5” Fixed Install Recommended for Rotator Loops DXE-400MAX Low-Loss Cable DXE-8U Low-Loss Foam Dielectric Cable [See The Velocity Factor] The most prevalent wire & cable insulation materials approved and generally acceptable for aircraft are from the Teflon® family — a familiar brand name for fluoropolymers — which include, for example, PTFE, ETFE (also known as Tefzel®), TFE, and FEP. 5. DX Engineering 300 ohm Ladder Line has 272 ohm nominal impedance and an 88 percent velocity factor. TABLE A: Insulation (e) Prop. 96. Available in 4 key sizes, there is a Poly-STEALTH ™ aerial wire designed to The velocity factor (VF), of a transmission medium is the speed at which a wavefront of a signal passes through the medium, relative to the speed of light. 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. The first can be more easily dismissed as insignificant, and that is the velocity factor of the metal. 2007-05-26. Twinlead Velocity Factor. I have only seen velocity factors specified for coax cables and other wiring designed for high speed/high frequency The outer insulation makes the wire kink-resistant, and its slippery finish makes it ideal for stealth antennas that must be passed through trees or other obstacles without snagging. 80 for typical two-wire lines and coaxial Velocity factor is not the cause of cable loss, but it is related. Fortunately for antennas, this means that much more of the EM field is forced out of the wire, into the space around it, where its velocity is more or less the speed of light. Under the assumption that the wire jacket/spacer material has a negligible effect on the electromagnetic fields, and that the line is suspended in air so that \(\epsilon_r\approx 1\), the phase velocity \(v_p\) for a parallel wire line is approximately that of any electromagnetic wave in free space; i. One can derive an analytical solution for the propagation velocity of a single wire with insulation in free space. com> Sent: Sunday, June 20, 2004 7:00 PM Subject: [TowerTalk] Velocity factor of insulated #14 Yes it does and a single wire velocity factor is part of the equation for a Dipole antenna. For common conducting metals the difference between two metals is very small and is generally swamped by other things that affect velocity factor, such as insulation. February 14, 2009 at 1:51 pm The counterpoise system was built using several insulated wires placed in parallel and spaced using some piece of PVC pipe . Antenna Wire. 81) Velocity Factor: 82% (0. 83, meaning that 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. , \(c\). —also called propagation factor—describes the attenuation and phase shift of the signal as it propagates through the transmission line. Table 4 -Dimensions and impedances with and w/o insulation. TFE insu- Typical 300-Ohm TV cable has a velocity factor of about 0. Source: Wikipedia - Velocity factor Investigating how Velocity Factor and End Effect play into antenna design. 95 ie approx 5% higher design frequency to compensate. If the signal travels at the speed of light, its velocity factor would be 1. 419 meter for the bare copper wire and a resonant length of 10. 10 MHz is 10 meters . Source: Wikipedia - Velocity factor In NEC-4, we can enter the required data in the IS command and obtain automatic calculation of the effects of the insulation. multiple conductive elements. eg if pvc coated wire is used to construct the antenna then the velocity factor drops to approx 0. If the radiating elements are made from bare copper copper wire, Use the new EZNEC which allows you to employ insulation over wire and adjusting the thickness to conform with results found experimentally with real wire at actual length; light is known as the velocity factor, or Velocity of Propagation (VOP), expressed as a percentage of the speed of light in free . For example, a velocity factor of 0. In contrast, open wire line tends to have a velocity factor close to 1. The velocity factor, ν ν, represents this slowing and is less than one (except in free space, where it is exactly one). The velocity factor of air-insulated, parallel conductor transmission lines is a lot closer to 1 than the velocity factor for coaxial cable. There are two aspect you'll need to take into account. It is excellent for quads, dipoles, long wires, and rapid deployment (spooled-out) antennas. EZNEC antenna modelling software courtesy of Roy Lewallen W7ELMusic by Bensound. 158 meter for the insulated wire, resulting in shortening factor of about 0. The dielectric constant of normal wire insulation (polyethylene) is about 2. 95 and the wavelength is 0. For example, the velocity factor of a copper wire is set by default to 0. Physical Characteristics (Overall) Conductor AWG: # CoaxAWGStrandingConductor MaterialDia. MIL-W-22759 wires are TFE- or Tefzel®-insulated. Insulation can degrade over time when exposed to UV and weather. This slowing effect is almost entirely caused by the dielectric material; in coaxial cables, the insulation between the shield and the center conductor. What is the significance of a velocity factor The velocity factor, $\nu$, represents this slowing and is less than one (except in free space, where it is exactly one). This slowing effect is almost entirely caused by the dielectric material—in coaxial cables, the insulation between the shield . 1 whereas water has a dielectric constant of about 5. 9%: 1. It has This factor is important in designing antennas and transmission lines to ensure signals are accurately transmitted and received. RG-58 type, 17 AWG solid . 95) in the measurements you’ve made. It would neglect the "ends", but would take light is known as the velocity factor, or Velocity of Propagation (VOP), expressed as a percentage of the speed of light in free . The term we use to indicate how much a conductor slows down the propagation of rf is Velocity Factor, often written as VF. I have only seen velocity factors specified for coax cables and other wiring designed for high speed/high frequency If you are using insulated wire you need to decrease the dimensions by roughly 4% as due to the velocity factor of insulated wire, it appears 4% longer to RF. 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. Velocity Factor = sqrt( 1 / P ) along the insulated wire. For FT8 and other continuous duty modes above 21MHz, suggest max key-down power of circa 500W to avoid stress and heat build up at the end of the element alternatively, you can “QRO” the end of your wire by making a closed loop and This, of course, detunes the antenna. 1176 Total Number of Conductors: 1 Insulation can protect the wire and give it more or less visibility but is not otherwise necessary. 8, meaning that a wavelength of line is about 0. It takes time for later portions of the The velocity factor (VF), of a transmission medium is the speed at which a wavefront of a signal passes through the medium, relative to the speed of light. 25 * c/f * vf2 vf2 = velocity factor of twin lead used (for commonly available 300 ohm twin lead using 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. FLEX-WEAVE TM is the "Cadillac of aerial wire". This gives rise to skin effect, and is why it's so shallow: the index of refraction is huge. DXE-LL300-1C - 100 Foot length DXE-LL300-2C - 200 Foot length The velocity factor reduction is a result of the insulation increasing the self capacitance of the wire For a conductor in free space the thin layer of insulation has little effect. 73! Anderson – PY1VHF – Macae/RJ. When running a wire down a pole, especially when spriraling down the pole (which is the correct way to run the wire), the velocity facto decreases by 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. com Electrical length is defined for conductors carrying alternating current (AC) at a single frequency or narrow band of frequencies. The bottom line in each series lists the 30-MHz resonant Velocity factor is a property of electromagnetic wave propagation, not wire. e. Er=3. 66 and 0. Instead of reflection factor, one can also use the term pulse return loss: A p r p = 20⋅ 100 log in dB (16) r p - pulse reflection factor in % The magnitude and nature of the pulse reflection factor depend very much upon the v = propagation velocity of the signal along the transmission line in Table 7. Description. 0, and for one traveling at half the speed of light, it would be 0. The more commonly used insulation's are listed in Table A. The velocity factor (VF) of a conductor is a measure of how much slower an electromagnetic wave travels through a medium compared to its speed in a vacuum. For a closed-cell foam dielectric, for Velocity in wire is very low, because the permeability is 1 and the permittivity is j1000s give or take. edu> To: <antennaware@contesting. For example, ladder line has lower loss than small-diameter Velocity in wire is very low, because the permeability is 1 and the permittivity is j1000s give or take. Legendary Mil Spec DX10 Arctic Grade (Type 8) antenna wire, tested by M0MCX, key-down at 1600W for 65 seconds at 14MHz. The maximum current capacity for a wire is affected by the wire size, ambient temperature, the material of the conductor, cable type, whether the cable is open to the The pulse reflection factor at a certain position is the ratio between the voltage of the reflected and the incident pulse. 4” Minimum Bend Radius: 5” 2. 26: 65. space. 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 Investigating how Velocity Factor and End Effect play into antenna design. Bill: I recall a figure more like 97% (3% shortening) for insulated wire. George says. 66) Minimum Bend Radius: 6” Repeated BendsMinimum Bend Radius: Minimum Bend Radius: 2. Moxgen DOES NOT allow for insulated wire. 95 of that in free space. Velocity Factor: 84% (0. However, this is the velocity factor for difference mode signals, with the current travelling in opposite directions on the two conductors. 0, depending on the number and type of spacers used. Velocity: v c: Transit time micro-sec/1000 ft. 06**** Polyethylene: 2. * This sample maximum current capacity is given for a single insulated wire with 90°C insulation in free air with an ambient temperature of 30°C (86°F), NEC ® table 310. Peter VK2TPM's blog inspired this project. 8 times the free-space wavelength for the frequency of use. Typical twin lead has a velocity factor of 0. 95 of that predicted by MMANA-GAL. Consequently wire lengths would need to only be 0. Reply. Velocity factor is only applicable to transmission lines i. (mm) 1 17 Solid BC - Bare Copper 1. By comparing, for example, the resonant length of a bare wire and a wire with a given type and thickness of insulation, we can obtain the velocity factor of the insulated wire in antenna (not in transmission-line) service. com This showed up a resonant length of 10. As Peter reported problems with KC7CCR's dimensions, I decided to characterise the twinlead available in VK-land, assuming it might be different enough to be causing the problems. This is not to say that velocity factor isn’t a real phenomenon, just that it isn’t a factor when cutting a length of wire for use in a dipole. Since this is a measure of velocity, not resistance, it is not affected by the length of the wire, impedance, or resistance -- those would affect the characteristics of the wave, but not the velocity of the wave. Insulation can change the velocity factor so should be accounted for when measuring antenna lengths. 975 Maybe this is of interest. Values light is known as the velocity factor, or Velocity of Propagation (VOP), expressed as a percentage of the speed of light in free . Air--**** Nom: 1. 95) (This radiator uses just one leg of the twin lead extended from BDEG) BD = EG = 0. 8 means the wave travels at 80% of the speed of light in that medium. This Insulated copper wire intended for home wiring is often used for antennas and ground systems, both elevated and buried. [5] This current flows through a given conductor such as a wire or cable at a particular phase velocity. The second, and more By comparison with the bare-wire length, we can arrive at a Wire VF or velocity factor for the specific insulation condition. This means the antenna is suddenly too long for the intended frequency because the velocity factor of the conductor is now higher than it was when the antenna was cut. 555 as the target and you're using insulated wire, putting in 29MHz should get you close to where you want to be. com>; <towertalk@contesting. MIL-W-22759 wires are TFE or Tefzel® insulated. mit. Also known as window line, this is the same high-quality ladder line used in DX Engineering multi-band dipole antennas. This is sometimes expressed as a velocity factor of . A transmission line (like coax) is a conduit for an electromagnetic wave in itself, so the velocity factor can be Velocity factor is a fractional value relating to a transmission line’s propagation speed to the speed of light in a vacuum. High Strength BC Antenna Wire. (Sources: Belden Catalog, Times Microwave LMR catalog; Davis RF web site; ERI catalog) For a parallel-wire line with air insulation, the characteristic impedance may be calculated as such: If the transmission line is coaxial in construction, the characteristic impedance follows a different equation: Velocity factor is a fractional value relating a transmission line's propagation speed to the speed of light in a vacuum. Source: Wikipedia - Velocity factor Wire Insulation Not all dielectrics are suitable for use on wire and cable. This means the antenna is suddenly too The velocity factor (VF), of a transmission medium is the speed at which a wavefront of a signal passes through the medium, relative to the speed of light. In fact, it shows a systematic rise as we increase the value of loss tangent, as shown in Fig. When filling the space between two conductors, like coax or twin lead, the effect is much greater. There can also be dielectric loss in the insulation. If you want 27. The NEC-2 engine, used by many antenna simulation free programs, has no direct way to simulate insulated wires. 17. One factor does change: the feedpoint resistance at the 30-MHz resonant wire length. 044" bare copper conductor, gas-injected foam HDPE insulation, Duofoil® (100% coverage) + tinned copper braid shield (95% coverage), polyethylene jacket. Poly-STEALTH ™ High Strength Aerial Wires are manufactured with high strength, high conductivity Bare Copper-Clad Steel (BCCS) and insulated with a high quality UV Resistant Polyethylene to provide you with one of the strongest and longest lasting antenna wires on the market today. The approximate physical length of an air-insulated, parallel conductor transmission line that is electrically one-half wavelength long at 14. and the center conductor.