Best efhw loading coil calculator L = 585 / f. This loaded dipole antenna calculator was developed to quickly estimate the inductance required for a coil-loaded dipole antenna, using slider widgets. Reply. It also acts as a loading coil on 80m. Radiators shorter than about 1/4 wavelength are capacitive, and generally use a series loading coil. 5ft. Inputs via the slider widgets: f : The frequency of operation in MHz. What does it do and do you really need it? Maybe you don''t. the insertion of a 70uH loading coil. Single Wire/End Fed Antenna description. Coil inductance calculator 2 thoughts on “A loading coil for 80m” John says: January 7, 2021 at 10:52. Diameter of the conductor If you want to use the End Fed Half Wave Antenna on the 80-meter band without increasing its length, you can use a loading coil. Availability: 7; Short Description: A short HWEF with a 49:1 unun and a loading coil situated towards the end of the wire making this antenna 66 At that point if the higher bands still resonate too low, move the coil inboard a little bit — that is, less wire between the transformer and the coil, and more wire between the coil and the free end. I pursued two methods of applying the loading: 1. Peter G3OJV takes In this view, the distance between the feed point (end of the existing 20/10 m EFHW antenna) and the loading coil would be 0 m. EFHW 40-10 Wire Antenna installation and testing Sunday - July 11, Create a loading coil for 40M to shorten the wire to a total of 37 feet; so I ordered one and while waiting I used an online helical coil calculator and I came across the following antenna which covers the 80-10m bands with no traps and just one loading coil. 1 – July 11, 2021 Figure 1: A typical inverted-L EFHW antenna setup with one bypassable loading coil. This calculator simplifies the process of designing an EFHW antenna, providing quick results for various amateur radio bands, and helping users build efficient antennas for There is a detailed calculation formula from OE5CWL/OE6CWL for the inductance that achieves the correct shortening factor for 7Mhz and the resonant frequency (14Mhz). Coil acts as both a Half-Wave (EFHW) Antenna Stephan M. Resonance may also be observed at Antenna loading coil calculator; Air Cored Inductor Calculator; Support; T&C. 00; Qty: Let's Build an EFHW Antenna If you attended Field Day 2022, you may have been one of the students that learned how to build an end fed half wave Antenna and actually got to build one and take it home. Comes pre-tuned (40-10m only) with heavy duty end insulator, ring terminal and shrink tubing. The length of the wire beyond the coil has to be adjusted for the desired portion of the 80 mtr band (or of the 40 mtr band, if making the 40-10 antenna) and the local environment. By center loading my vertical with a 4' mast under the V. As seen on his page, the original formula seems to Using the EFHW Antenna Calculator is straightforward: Input Frequency (MHz): Enter the operating frequency of your radio equipment in megahertz (MHz). Moving the pot up and down gives a feel for the SWR versus antenna impedance sensitivity. First, you need 260 feet of wire and no coil on the antenna. Once I had upgraded the matching transformer for my EF-10/20/40 MKII "EndFedz" (see Part 1) my thoughts turned to the loading coil. 00. The impedance of a end fed wire can be anywhere We can instead build an antenna for 20m and electrically extend it for 40m using a loading coil with a tail wire at the end. November 10, 2022 at 11:01 However, though an EFHW "Inverted L" would be perfect in terms of installation practicality, I'm afraid of causing RFI to our house and our neighbors. Can an EFHW antenna be used for multiple frequencies? Total length of antenna in feet Open the dipole length calculator in a separate page. 3K subscribers Subscribe 29K views 4 years ago The little coil helps place the EFHW resonance points where we want them. . Delivery Information; Kevlar EFHW 49:1unun 80 / 40 / 20 / 15 / 10 m 300W Short with coil. [1. That's your EFHW from 40m-10m. 00; Is there a good antenna theory explanation for the best counterpoise placement with an EFHW? I've tried it several different ways, and the difference is hard for me to tell. Will cover 80m/40m/20m/15/10m. 5 uH) about 30 feet from the feed point on the EFHW16040 to get 60 and 40 meters to resonate. attached to a fixed support, and the other attached to the load that moves with the load. In general, an HF loading coil can be treated somewhat like a transmission line with a characteristic impedance and electrical length. To get to 110µF I used 76 turns. The 6-turn loading coil lowers the resonant frequency into the CW portion of the 40 meter and higher bands. [10-100 %] Half-Wave (EFHW) Antenna Stephan M. The original coil is designed for low power portable applications. 40m version, WA7ARK found a cap in the middle does the trick, lengthen the antenna for the upper bands, the cap shortens 40m back to resonance. Variables: L is the length of the antenna in meters ; f is the frequency in MHz ; To calculate the length of a 5/8 wave antenna, divide 585 by the frequency in MHz. 0 reviews / The coil is a loading coil or 'trap'. 2 – August 17, 2021 Figure 1: A typical inverted-L EFHW antenna setup with one bypassable loading coil. There is also a largely ignored current "bulge" inside a loading coil that affects losses in This calculator is useful when making antenna matching units, low pass filters, crystal sets, antenna traps, resonant circuits or anywhere where an air cored single layer inductor is required. With about 71 turns of 20ga. This would include dielectrics on or near the inductor, since the presence of dielectrics would increase undesirable capacitance. As others have mentioned a (not so) random length antenna would work as well. The Turns per Inch area, above, is used as a Output when Bare or Enameled wire is selected, however, it is used as a Input when Insulated wire is selected. If you add this coil to the end of a 40-meter EFHW element (~67 feet), and then add about 7 feet of wire on the fare side of the coil, you should be able to tune a narrow slice of the 80-meter band. Figure 3 (from reference 4, modified by N7TWL As noted in figure 3, the feed point for a dipole is in the middle. Using a 49:1 transformer shoot for the best 50 Ω match @ appx 2450 Ω load over your working frequency bands. I have built several EFHW antennas using commercial and my home brew transformers and all worked good with SWRs below 2:1 on 80-17 meters but were around 3:1 on the higher bands even with compensation coil. The loading coil is connected in series with the antenna and is placed at the end of the antenna. Calculate Length: Designing an EFHW antenna is made easier with the EFHW Antenna Calculator. Defaults to 80% of a half-wave dipole. 5uH, so this is what I built. This is an End Fed Short Wire wire antenna that will cover all bands from 80 / 40 / 20 / 15 / and 10. The coil and the short tail wire (about 6 feet) make up the other quarter wave on 80m. ) If phone operation on the Loading coil former for a shortened 80-meter band EFHW. I'd like to be able to tx at 100W+ and that might cause some issues Antenna loading coil calculator; Air Cored Inductor Calculator; Half Wave End Fed Antenna; EFHW WIRE AND COIL 40 / 20 / 10 m 150W Short with coil. ) If phone operation on the W6TRW Amateur Radio Club – Home of the W6TRW ARC in Redondo Beach, CA Thanks Vittorio. A place to discuss all aspects of amateur radio operation. is this simply a function of the loaded vertical design? (Whereas with an EFHW one is needed) Thanks! Michael KD7PTZ. Click to find the best Results for 110uh loading coil form for short efhw antenna by Models for your 3D Printer. A random length of wire fed directly from the output of your transmitter (Fig-1). What a loading coil is, and how they are used to reduce the physical length of a resonant antenna. By using our site you consent cookies. 5m. 3. The loading coil inductance should be around 30uH, but I found it difficult to get accurate readings of both the original and replacement coils on the bench. Since the EFHW antenna is in the dipole antenna family, it might be best to look at the voltage and current distribution of a typical dipole antenna first. This is often the simplest and sturdiest situation, but it is also the least efficient. Distance from center of antenna to the center of the coil in feet (Must be less than half the total antenna length given above). 5' tall stainless steel collapsible whip, my portable vertical is about 14. So a loading coil is added. 6 MHz] l : Length in percent compared to a half-wave dipole. 5 The 6-turn loading coil lowers the resonant frequency into the CW portion of the 80 meter and higher bands. -Use 20ga. At the end of the 20. By adjusting I wound the coil with two windings and then removed one of them to leave a coil with turns spaced one wire diameter apart. EFHW WIRE AND COIL 40 / 20 / 10 m 150W Short with coil. Could you possibly clarify what you mean by ” I measured the impedance of the antenna at the point where I anticipated the matching coil would be located. WB8ERJ says. The 6-turn loading coil lowers the resonant frequency into the CW portion of the 80 meter and higher bands. Have fun! Best 73, Bob AK3Y Figure 1 – EFHW Transformer Unit and Antenna Wire Changing the Resonant Frequency The 6-turn loading coil lowers the resonant frequency into the CW portion of the 40 meter and higher bands. 110uH Loading Coil Form for Short EFHW Antenna thingiverse. 2. For Enamled Wire, the spacing between turns is In today's video I show you how to turn your 40-10m EFHW into an 80-10m EFHW with an inductance coil. The result will be the length of the antenna in feet. 5m of wire connected to the transformer. 00; Qty: Add to Cart. Antenna loading coil calculator; Air Cored Inductor Calculator; Cookie_Policy; EFHW 49:1unun 40 / 20 / 10 m 150W Short with coil. Hi there, thanks for the article. Enter the number of turns (windings). The voltage is at a minimum, and the current is at its maximum. Use the Formula: The formula to calculate inductance (L) is L=31. The wavelength calculators used to calculate the antenna element dimensions will therefore use the speed of light (299792458 meters per second) in a vacuum as constant. By placing the loading inductor on the antenna The little coil helps place the EFHW resonance points where we want them. I ordered one of these for a 1:64 40-10 EFHW. That can be useful when the user wants to change the trap frequency, use a different coaxial cable, or has different coil form material than what is specified in the second section. How does the EFHW Antenna Calculator work? The calculator uses the formula L=468fL = \frac{468}{f}L=f468 to calculate the antenna length, where fff is the frequency in MHz. It works VERY well. Using the diagram below: Is the coil always 2 meters from the feedpoint? Coil Inductance Calculator To calculate the inductance of a single-layer, air-core coil: 1. I highly recommend it for those with limited space. Every Day new 3D Models from all over the World. With an online calculator (e. Select the measurement units (inches or centimeters). Brand: Wire Antennas UK; Product Code: EFHW 49:1unun 40 / 20 / 10 m 150W Short with coil ; Availability: 8; £65. 00 Ex Tax: £65. Table of Contents 1 Summary and Purpose of this Document. It brings in 80m superbly. The original javascript was created by Jack Ponton and can be seen here . It requires a set distance to hang both ends of the antenna, and that is not always given. 8/f, where “f” is the frequency in megahertz (MHz). 66pacific. Retune the antenna for the lower bands, the inductor has greater effect on the upper bands and re-aligns the harmonics. Following that is a section that allows the user to create a custom trap using their specified frequency, coax, and coil form. A standard dipole antenna is resonant if constructed with a length of one-half wavelength. In his YouTube channel, Tim G5TM proposed using a 35 microhenry loading coil with a short tail wire. The reason for reducing the size of the antenna is to enable operation on smaller house allotments as well as being compact enough for portable work. When the rope is pulled, the tension of the rope is applied multiple times to lift the load, multiplying the EFHW 80M Loading coil. Coil acts as both a loading coil for 80-meters and a "trap" thanks to it's internal capacitance, so adding it to the 40-meter band half-wave element will not change the tuning on 7 MHz and above. I used standard 40mm PVC pipe from B&Q and 20SWG enamelled copper wire, which is 0. This is the BEST EFHW article I have ever read. The coil effectively stops the RF current flowing in the final 2m or so of wire at 7MHz and above. I am adding a loading coil to the out end of the efhw to add the 75 meter band to it. I will start with probably the simplest antenna you could think of. 00; Ex Tax: £65. Do not cross over the winding. Total length with the inductor is typically 23m or 75. Add or delete secondary turns from “design” to yield the best match versus the resistance presented by the resistor/pot. May want to mount the house side end to the pole you already have that is just above your roof line. g. Use a 200 pf capacitor instead of 100 pf. When installing a loading coil of substantial inductance in an electrically short antenna, sheetmetal and dielectrics should be kept away from the coil and areas of antenna above the loading coil. EFHW 49:1unun 80 Loading coil 8 ft from one end. Usually not needed. A 110uH inductance coil is a perfect addition for those This way, I can build it with a 16 turn secondary, and at the inductance I wanted by altering the diameter and/or length of the coil. By adjusting the number of turns on the loading coil, it can act as a loading coil and a choke, isolating the 80-meter I needed to add an additional coil (approx 12. For the loading coil form I decided to use an In Sink Tailpiece. . In 54 years of hamming, these have been (by far) the best wire antennas that I have used. I haven’t tried it on 10m yet but the CLEFHW should theoretically behave in the same way as a full length wire EFHW. The antenna is basically the design described by VK3YY at We use cookie to improve your experience on our site. (And all my responsibility is hereby disclaimed!) I haven't personally tested these designs, but others have and found them to be satisfactory. Add to Cart. I used a little hot melt glue to hold the turns in place. com Resources for amateur scientists :) : Online Calculators for Radio and Electronic Design Use these online calculators to determine reactance and the inductance and coil windings for toroidal and conventional coils. This antenna has a very high feed impedance, 2000-3000Z Ohms, so to match it to your typical 50Zohm radio, you will need a matching device called an UnUn, with a ratio of 49:1 Antenna loading coil calculator; Air EFHW 49:1unun 80 / 40 / 20 / 15 / 10 m 200W Short with coil. This online calculator tells you the amount of inductance your loading coil we need to have. (The antenna wire could also be tuned for the lower end of 80 meters without the coil but the resonance on the higher bands will be progressively higher in the bands. I use a Yaesu FT818ND with an efhw for portable cw operation. 00; Qty: 1920 "110uh loading coil form for short efhw antenna by" 3D Models. Several companies sell a shortened antenna Product Code: EFHW 49:1unun 80 / 40 / 20 15/ 10 m 200W Short with coil. 00; Qty: With an antenna, if you are near a band edge and have a 2:1 swr, it is usable unless you are a purist, then you can use a tuner to knock it down. £65. 5m wire connect a 110uH inductor and 2-2. By simply entering your desired frequency, you can quickly determine the optimal antenna length for The Single Element loaded vertical (left) has a loading coil inserted at the base of the antenna element. The slim coil is torpedo shaped to prevent it being snagged in trees when deployed in 'the great outdoors'. Like Like By short, I mean 160-meter antennas up to about 60 feet in height to the loading coil. Radio waves behave very similar to the photons in light waves. A rope is looped multiple times over both the fixed and load pulleys. Diameter and length of inductor are entered in millimetres along with the number of turns. magnet wire wound tight on this form, you should get about 110uH of inductance. 5' tall overall. Inserting the loading midway on The K4VX Linear-Loaded Dipole for 7 MHz Here’s a very simple and practical way to make a short but efficient 40-meter dipole. Excellent build quality with a great attention to detail. 00; Ex Tax: £43. A vertical antenna (effectively half a dipole operating against a ground plane) is resonant at one-quarter wavelength. I have given much consideration to the coils used, and to their placement in the loaded antenna. An “End-Fed Half-Wave (EFHW)” antenna. These are all the mechanical parts to build a superlight version of a popular design for a compact tri-band endfed antenna for 40, 20, and 10 m with a loading coil. It is called the EFHW-8010 . Enter the coil diameter (form diameter + wire diameter - see diagram). The following formula is used to calculate the length of a 5/8 wave antenna. The inductor acts as a loading coil and a trap. Intro EFHW Compensation Coil Experiment Steve Ellington 10. E. 5 2 Definition of the Described EFHW Antenna Loading inductors are used to electrically lengthen the antenna. Antenna loading coil calculator; Air Cored Inductor Calculator; Half Wave End Fed Antenna; EFHW 49:1unun 40 / 20 / 10 m 150W Short with coil. Ian – 16 April 2023. Short Description: EFHW Kevlar Wire antenna which is 66 feet / 20 meters long incorporating a loading coil to suit small modern gardens working 80 / 40 / 20 / 15 / and 10 meter bands. 00 Ex Tax: £105. Schmid, HB9EAJ Version 1. ; For Bare Wire, the spacing between turns is calculated as twice the wire diameter. PD9JS - RF Antenna calculators for various antenna types Back to Telecommunication. Antenna loading coil calculator; Air Cored Inductor Calculator; EFHW 49:1unun 40 / 20 / 10 m 150W Short with coil. EFHW 49:1unun 80 Antenna Loop Calculator; Half Square Antenna Calculator; 5/8 Wave Antenna Length Formula. I can’t wait to use your ideas to test a new EFHW I am building. enamel coated magnet wire for windng 80 Meter Coil Assembly Parts: PVC coil form, light gray (1) Aluminum end caps (2) 8-32 x 3/8” stainless Phillips screws (4) #8 internal tooth lock washers (4) #8 ring terminals (2) #22 Enamel insulated copper wire (red) The coil is assembled using the 2 larger end caps, the larger light gray PVC coil form and 4 of the 8-32 x 3/8” screws. 2 coil (scroll to the bottom of this page for more info on why I center load my vertical), and a 9. When winding, a length of the same size wire is used as a spacer, and then removed. 914mm in diameter. ) I'm making my first EFHW antenna and was hoping to understand the typical application for the compensation coil. For those that were not able to do so, this You can do a ~75ft, 80-10 EFHW using a loading coil. (The antenna wire could also be tuned for the A common shortened design is 20. I've seen advice to put the counterpoise perpendicular to the antenna wire, or parallel to the wire (under it) laying on the ground, or elevated a few feet above the ground. each side of the span, which requires two additional insulators. from M0UKD) you can easily see that the required coil inductance for a short antenna tail on 40 m is much larger than that previously determined for the choke function and that this function is therefore Just wondered if I could pick your brains on some antenna theory. Will a loading coil have the same effect on a end-fed ½ wave (vertical) as it does on a ¼ wave vertical (ie allowing you to shorten the vertical radiating element)? My gut feeling is that it probably won’t work because an EFHW is already fed at a very high impedance (hence the need for the 49:1 Loading Coil The 110µH loading coil is used on the version for 80m. 4. Brand: Wire Antennas UK; Product Code: EFHW 49:1unun 80 / 40 / 20 15/ 10 m 200W Short with coil. Using this Air Inductance Calculator , I worked out that a 19mm diameter, 52mm long, 16 turn inductor should give an inductance of 1. 00 When installing a loading coil of substantial inductance in an electrically short antenna, sheetmetal and dielectrics should be kept away from the coil and areas of antenna above the loading coil. It is simply a half wave end-fed on 80m which will resonate on all multiples of that frequency, loaded with a My Shorty 80m EFHW comprises a 49:1 autotransformer (to match the very high impedance at the end of a half-wave wire), a half-wavelength wire for 40m (also a quarter-wavelength for 80m), a loading coil and a short tail wire. Assuming a practical limitation on how large one can Coil is only 98 uh so i had to make the stub longer (7 feet) SWR on the other bands is much the same, Infact its reduced my SWR on 10m Don't expect 80m performance to be anything special, But should be slightly better than an 80m mobile antenna as it has less loading An antenna loading coil is an inductor placed in series with an antenna element in order to lower the antenna’s resonant frequency. Build an effective, shortened vertical antenna by adding a loading coil. To get the best performance though, I would probably shorten the whip to a half-wave on 10m, bypass the loading coil and use the antenna as a standard vertical 10m band EFHW. What is an Efhw Antenna? An EFHW (End-Fed Half-Wave) Antenna is a type of radio Here is a formula and calculator for creating a loaded (shortened) quarter wave vertical or balanced dipole. The nominal inductance of the loading coil is 110 μH for the 80-10 antenna, and 34 μH for the 40-10 version, see ref. In this case the coil makes the resonant on another band. try 450-Ω ladder line as the linear-load-ing mechanism. 8-57. Enter the coil length (distance from first to last winding - see diagram). (The antenna wire could also be tuned for the lower end of 40 meters without the coil but the resonance on the higher bands will be progressively higher in the bands. I’m from Colorado in the States. 5 2 Definition of the Described EFHW Antenna HF Double Bazooka Calculator; Groundplane Calculator; Quad Antenna Calculator; Yagi Antenna Calculator; Make a Vertical Bazooka; Coax losses Calculator and Charts; COAX PHASING calculator; DIY Wire Antenna Calculator; Dipole Calculator; HF Trap Calculator; coax trap calculator; Antenna loading coil calculator; Air Cored Inductor Calculator Product Code: EFHW 49:1unun 80 / 40 / 20 15/ 10 m 200W Short with coil. Availability: 7 Short Description: A short HWEF with a 49:1 unun and a loading coil situated towards the end of the wire making this antenna 66 feet / 20 meters long + 6 foot of end tuning wire for the 80 meter band makes this antenna a superb choice for 80 / 40 / 20 /15 and 10 meter bands. There are some changes if you want to do a 160m EFHW antenna. Brand: Wire Antennas UK; Product Code: EFHW WIRE AND COIL 40 / 20 / 10 m 150W Short with coil ; Availability: 10; £43. The To calculate the length of an EFHW antenna, divide 468 by the frequency in MHz. I only have space for a 39' antenna; this is sufficiently long for operation on 10m (full wavelength and 20m, but at 40m it's too short. Supposedly these antennas are a bit unpredictable in terms of how much interference they cause nearby. If you want to use the End Fed Half Wave Antenna on the 80-meter band without increasing its length, you can use a loading coil. £105. ” and how you did this ? To calculate the inductance of an antenna trap, you can follow these simple steps: Gather Information: You’ll need to know the frequency (in MHz) at which you want your antenna trap to resonate. Ideal replacement for our multi band antennas, or adding to the 49:1 transformer. Availability: 6 Short Description: A short HWEF with a 49:1 unun and a loading coil situated towards the end of the wire making this antenna 66 feet / 20 Antenna loading coil calculator; Air Cored Inductor Calculator; Cookie_Policy; HF; 10M; EFHW 49:1unun 40 / 20 / 10 m 150W Short with coil. The feedpoint resistance will be less than 50 ohms, unless ground losses are high, or some other form of matching is used. That little coil that sits at the end of some commercial designs for the EFHW. Approx lentgh 22. Antenna loading coil calculator; Air Cored Inductor Calculator; Support; T&C. 26 posts 1; 2; Next; Buick Mackane Moderator Posts: 9726 If you're making your own coil, this is the best calculator imo because it allows you to put your target henries value in and spits out the required dimensions based on what you have https: 110uh loading coil for 80m Originally I had bought the 40 to 10m efhw. At 7MHz, the impedance of the loading coil is about 3kΩ, and this effectively disconnects the tail of the antenna at 40m and above. Antenna Loading Coil Calculation The calculation method is taken from a BASIC program which I got many years ago from OA4/KA2OIG who is hereby gratefully acknowledged. EFHW 49:1unun 40 / 20 / 10 m 150W Short with coil. This is an End Fed Short Wire wire antenna that will cover all bands from 40 / 20 and 10 meter. 5m of wire to tune 80m too. The transformer should be 3 - 43 mix cores with 3 primary and 21 secondary windings (up to 30 depending on SWR). ftvpr fdn pzfboe eyfqh ixtlb mrxrbe wcr sgj mmtmphy ojvh