Mar 19, 2018 this is the best wire antenna i have tried. The voltage at the end of an efhw is easily estimated using the fomula esqrt pr where e is the voltage, p is the power in watts and r is the end resistance ohms of the antenna. Sometimes however, the centre feed is not ideal, for example when you want to use it as a vertical. This is a presentation i gave at norfolk amateur radio. Habits born form the use of centerfed halfwave antennas do not apply to the endfed case but they almost do. Radio waves behave very similar to the photons in light waves. Antenna design calculators jeroen steeman software. Efhw antenna without a counterpoise may well give rise to problems of various. The mathematics to describe this catenary curve defied solution until calculus was invented. Obviously, an efhw antenna has a halfwave length only at one specific frequency.
You cant, for example, generally use a 40m efhw antenna on 20m. The coupler mounts directly to the rear of the rig via the bnc plug and the end fed half wave antenna connects directly to the banana jack. But be warned endfed antennas can be noisier and also cause more emcinterference problems. About the efhw antenna the resource is currently listed in in a single category. A special case of this, is the endfed halfwave efhw antenna.
End fed antenna ideas antenna, ham radio antenna, ham radio. Qrp multiband hf efhw antenna for sota post updated 29 september 2017. This matcher is designed for feeding the high impedance of endfed half wave wires, so the length of wire is determined by the operating band and needs to be cut for a half wavelength on that band. Antenna calculator for hf antennas ham radio secrets. If they rely on the earth for the current return they are not balanced antennas starting with a halfwave dipole we can see how a quarter wave vertical is derived. Stainless hardware, uv resistant materials throughout. For most hams, an endfed antenna is and endfed, halfwave, or efhw, antenna. If it doesnt then the 5 band efhw is better as it can be built to need no tuner on the 5 bands. The following table gives a few data points to consider. Attach one end of your antenna wire to one of the binding posts, either directly or using a jumper wire. Portrayed below is a complete and selfcontained nec model of one popular form of the endfed halfwave dipole antenna.
The antenna tuner will load an end fed long wire effectively, especially if it is cut to aprox. Setting out to explore the world out of efhw antennas that have dominated the discussions nowadays. This antenna can be angled anywhere in a range from 0 as a halfwave vertical dipole, to 90 as a flattop horizontal dipole. Comparison between the efhw and dipole on 20 meters. But performance is down about 812db on a dipole on. Dipole antenna ham radio antenna good communication calculator wire radios hams workbenches circuits.
Such a problem can be solved by mounting a dipole at a slope. Full hf coverage, no tuner needed on most frequencies. The efhw end fed half wave needs to be classified as a specific case of the class of end fed wire antennas. Centre fed half wave dipoles make great, simple and effective antennas for the hf bands. Rf antenna calculators for various antenna designs back to telecommunication.
Jd, i dont have any antenna modeling software using a tablet but the concept of an endfed halfwave dipole is foreign to me, to whit the dipole antenna, how industry defines it etc. After some success with the original end fed half wave antenna tuner on a couple of sota activations, it was time to make it a bit smaller and change a couple of things. The latter is treated as a lowloss singlewire transmission line. The measurements below are for building a simple dipole antenna. There are usually four radials, three being a minimum, but you could use up to six. Endfed antenna for qrp portable ops ham radio site. When you design a coupler for this antenna it helps to know what turns ratio you should use. The results are conveniently displayed in inches, centimeters, feet and meters.
A multiband efhw may be better as it is not so dependent on an earth and the radiation maximum is higher up the antenna. This page contains various javascript based calculators for electronics. For this application i removed the jack and installed a banana plug jack. If you have a tuner, then the 8010 efhw is easier as it is lighter, smaller and less fragile given it has no traps. Using the technique of your choice, support the other end from a tree or other tall support. Efhw portable antenna for sota activations mention to anyone you are using an efhw will prompt a discussion about the pros and cons of the efhw versus the center fed 12 wave dipole.
The end fed is not suitable for vhf frequencies, but you can tune a half wave whip to 50 ohms using a coil and capacitor. Describe your experience with the myantennas efhw8010 antenna and tell us why you give it the rating you did required. The antenna could be used as either an inverted v or a half wave vertical on the higher bands the challenge with the efhw is feeding it as the end is a high impedance point apparently between 2000 6000 ohms depending on the surrounding environment. One end goes straight into the rig, often with no feedline, and the other end in the air attached to something as high as you can find. Feeling a bit too lazy to calculate that by hand, however, i wrote a program or two to do all. Efhw 8010p 200w portable or stationary multiband end fed half wave antenna. The free mmanagal software has a built in trap calculator.
If you only have one support an endfed antenna may suit you better. If you have no particular preference within a given ham radio band, then simply enter its center frequency i. Kb6nu finally builds an endfed, halfwave antenna kb6nu. The antenna has a full 300khz bandwidth on 80m between 3.
Endfed half wave efhw antenna modeling with mmanagal. Keep in mind the above is from measurements, not simulation. Coinductive and pdlii are trademarks and this antenna is most certainly covered by patents. Characteristics because a zigzag dipole can be resonant at whatever length desired, only the impedance is the limiting factor. However, it needs a tuner to get the swr low enough on some bands. The design seemed relatively simple to build, requiring only a single toroid and a capacitor made with a. How to create a counterpoise for an efhw antenna is hotly debated. Wire antenna calculator amateur radio ham radio station ws6x. The rationale behind this was not to find what people thought was necessarily the bestperforming portable. To this day, differential equations, integrals and specialized software are how engineers design bridges and arches. This is a presentation i gave at norfolk amateur radio club. As typically installed, it is a compromise antenna but great for portable use because it is easy to pack and easy to install. The loops of folded antenna have been replaced by v shaped elements without any changes and easier matching. G0kyas hf end fed half wave efhw antenna construction details introduction the efhw monoband matching unit inspired by aa5tb allows for a half wavelength of wire to be connected, giving a 50 ohm impedance match to the transmitter without a ground plane or atu at.
This formula to obtain the length of a halfwave dipole antenna will give a good ballpark value to start with. That also means the antenna has to have a transmission line. About efhw vertical antenna the resource is currently listed in in a single category. I have found this calculation to work well, however it depends on many factors such as wire used, location etc. Mmanagal is a popular antenna design, analyzing and modelling software tool, that is relatively easy to learn and use. The solution to this problem is to provide a counterpoise close to the antenna, which is low impedance on all bands of operation.
The very valid reason for this is that the high impedance of the feedpoint was outside the. Other useful information would include your experience with similar products, infomation on a product that you would purchase instead of this one, and so on. Mention to anyone you are using an efhw will prompt a discussion about the pros and cons of the efhw versus the center fed 12 wave dipole. Nov 07, 2012 efhw antenna tuner 2 posted on november 7, 2012 by vk3yy after some success with the original end fed half wave antenna tuner on a couple of sota activations, it was time to make it a bit smaller and change a couple of things.
G0kyas hf end fed half wave efhw antenna construction. This is a 200w version of popular efhw 8010 endfed halfwave efhw antenna for 80403020171512 and 10m bands. The name is even a bit of a misnomer since the efhw is often operated on multiple bands and therefore is no longer a half wave antenna. As the counterpoise itself approaches a half wavelength, the impedance approaches 5000 ohms. Expect a 12 s point improvement over a quarter wave or trapped vertical. This calculator can be used to design a quarter wave ground plane antenna, with radials. Mfj1984mp endfed 12 wave 300w 40m10m wire antenna 66 feet.
Most of the construction videos or sites teach how to make the 99. Slim jim and jpole antenna calculator build a cactus for any frequency. This is an endfed halfwave efhw antenna for 80403020171512 and 10m bands. You can also l shape it or zig zag it or slope it if you are limited on room. The g0kya efhw an endfed half wave monoband hf antenna, plus two multiband versions new. It is 148 foot of wire about 40 feet above ground between 2 tall trees. Using the loop calculator which takes into account not only the elements size, material aluminum or copper and length but the shape roundoctogonalsquare as well. So, a multiband endfed halfwave antenna is actually a bit of a misnomer.
Antenna modeling suggests that the impedance is closer to 1800 ohms depending on the counterpoise length used. The main category is endfed antenna that is about endfed antenna projects and plans. The following program will calculate the lengths needed to construct several popular wire antennas. Aug 12, 2016 for the past couple of weeks, ive been playing with endfed wire antennas. Simulations suggest what feedline lengths to avoid and offer a confirmation why portable users with short feeds never seem to have trouble. Field deployment for end fed wave antennas, kc8aon. This is a 200w version of popular efhw8010 endfed halfwave efhw antenna for 80403020171512 and 10m bands. A multiband wire antenna that performs exceptionally well even though it confounds antenna modeling software article by sk the design of the mystery antenna was inspired by an article wri were ee, the uks biggest network. The g0kya efhw an endfed half wave monoband hf antenna. This gave the antenna more gain than a simple quad. All you need to do is enter the desired resonant center frequency in the form below, then click calculate. A socalled random wire antenna is an end fed antenna.
I have documented some of the earlier ones i built in my pedestrian mobile pages. Does a 12 wavelength endfed antenna need a good rf ground. The survey asked just one question what is your favourite portable antenna. End fed half wave antenna coupler swr bridge, aa5b. A halfwavelength radiator has a high impedance high voltage, low current at the feedpoint. I found that the counterpoise connection was not really needed and the switch that connected the transceiver ground to the counterpoise ground. See more ideas about cable options, mp3 player and ham radio. That post basically criticized the seller of the qso king antennas being sold on ebay. A few years ago i built a little rockmite transceiver for 40m. All you need to do is enter the desired resonant center. A shortened multiband endfed half wave efhw antenna for 8010m steve nichols g0kya a shortened multiband antenna, about 23m long, for 80m10m that offers low swr 1. In the graph below i have plotted what mininec predicts for the impedance of an end fed half wave antenna versus the counterpoise length. The pomona box originally had a jack bnc connector on one end and a plug bnc on the other. A couple of months ago, i ran across a design rated at 100 w.
Mar 09, 2010 attach one end of your antenna wire to one of the binding posts, either directly or using a jumper wire. At opposite ends of the software landscape we have. Here is a simple antenna calculator for two popular forms of ham radio hf wire antennas. Here are some other examples of the end fed half wave antenna. Endfed wire antennas radio society of great britain. I havent done the calculations, but as built, id guess that its good up to. There have been many manufactures over the years that built half wave vertical antennas that had only a few short radials. In the world of ham radio a straight dipole antenna is rare because wire sags and tubing droops. The antenna is designed to be fed with 50 or 75 ohm coax cable of most any length with a balun. Method of moments technique to calculate steady state currents of each wire segment. The coupler converts the high impedance end of the end fed half wave antenna down to 50 ohms. Some simple maths is required to calculate the magnitude of the voltages at the end of the efhw.
The main category is efhw end fed halfwave antenna that is about efhw end fed halfwave antenna. The antenna tuner is a 1977 heathkit hft9, a small qrp size tuner of the capcoilcap doublel design. What hes selling isnt really what most hams think of when they think of an endfed antenna. Unlike most devices for this job, the minivna pro has been built for portability. Jun 12, 2019 the previous measurements of the diamond nr770hbnmo endfed 2m440 antenna with k515 luggage rack mobile mount reveal an efhw antenna that works just fine as this measurement confirms figure measured gain of nr770k515 and comet magmount. May 29, 2017 comparison between the efhw and dipole on 20 meters. Link end fed half wave antenna and tuner for sota get out. Oct 26, 2017 some friends and i have been talking about dong a camping trip, and i decided this would be a good opportunity to try some portable ops with an endfed half wave antenna. End fed half wave antenna coupler efhw m0ukd amateur. My favorite antenna for portable use is the end fed halfwave or efhwa.
This is a common antenna configuration in the world of amateur radio referred to as a sloper or more accurately, halfwave sloper. Unlike many end fed antennas on the market, this one does not require the antenna tuner to operate. As noted, this design is optimised for the 8015m bands. Endfed wire antenna lengths amateur radio stack exchange. Describe your experience with the efhw8010 8band end fed half wave antenna and tell us why you give it the rating you did required. Efhw antennas might have elevated swr readings on some bands due to the different position, height above ground or impact from nearby objects. A shortened multiband endfed half wave efhw antenna. The wavelength calculators used to calculate the antenna element dimensions will therefore use the speed of light 299792458 meters per. The endfed halfwave antenna can function alone, but feed lines are the norm regardless. Ive been doing a lot of reading on the subject, especially aa5tbs excellent explanation of the theory behind a resonant efhw antenna. The computed value of a series tuning component, l or c, when used to cancel jx will change feedpoint impedance to a pure resistance of r ohms. Efhw end fed halfwave antenna category is a curation of 27 web resources on, 20m halfwave end fed, the efhw antenna, efhw matching unit.
In figure 4 below can be seen how the impedance red line falls from around 70 ohms, to 50 ohms at 0. Endfed antenna for qrp portable ops by robert liesenfeld, ak6l published october 26, 2017 updated august 2, 2018 some friends and i have been talking about dong a camping trip, and i decided this would be a good opportunity to try some portable ops with an endfed half wave antenna. A shortened multiband endfed half wave efhw antenna for. In early 2014 i conducted an online survey for portable antennas. Aa5tbs excellent page for efhw info or, addressed below, to cut the wire so that it is not. The antenna then doesnt resemble the end fed wire that most people build. G0kyas hf end fed half wave efhw antenna construction details introduction the efhw monoband matching unit inspired by aa5tb allows for a half wavelength of wire to be connected, giving a 50 ohm impedance match to the transmitter without a ground plane or atu at the frequency of operation. Link end fed half wave antenna and tuner for sota get. One short wire is rarely sufficient, unless maybe if you only operate one band. Random wire antenna lengths university of delaware. One of the reasons for this is that most designs are for qrp antennas and not made to handle more than 5 10 w of power. Some houses dont really lend themselves to installing a halfwave dipole.
Unlike many end fed antennas on the market, this one does not require the antenna tuner to. Yes, most modern radios have an internal antenna tuner and there is nothing wrong to use a tuner to match the output of your radio to an impedance seen at the end of the coaxial cable. This link is listed in our web site directory since wednesday jan 26 2011, and till today efhw vertical antenna has been followed for a total of 3841 times. This link is listed in our web site directory since friday apr 20 2012, and till today the efhw antenna has been followed for a total of 1984 times. Effective jan 2016 i will be changing web hosting providers and as such a complete redesign of my website using a content management systemcms to better design and host the site. Antenna, ve3sqb ham radio antenna design software programs. Being able to feed the dipole from one end gives you more options on how to erect an antenna and makes. Of late ive been using this antenna mainly with my kx2. For vhf, anyone who has ever used the old aea hot rod end fed half wave antenna for an ht know the drastic improvement it made over a 14 wave antenna. Ive posted about endfed, halfwave antennas before, but until this weekend, id never built one.
Efhw8010p 200w portable or stationary multiband end fed half wave antenna. In fact, it is tiny and you can run it on nothing more than a lithium battery. Since i enjoy using end fed half wave antennas so much i built a small coupler to use with my rockmite. No long counterpoise, radials or feedline required. One is an efhwa for 2040 meters, and the other is a matching unit for the antenna. The antenna calculator above uses this formula as a starting point to calculate wire lengths for the dipole. Applying a feed to any antenna in nec or any electromagnetic simulation software is about a simple a task as can be conceived by placing a source of near infinitesimal size inline with a dipole element. There are operators who swear their center fed 12 wave dipole is 2 s points better than the efhw and vice versa. Remote loading unit for a 160 end fed antenna, g4gys. Before i get into the nittygritty details, let me first make a distinction between endfed halfwave antennas, such as the ones sold by lnr precision and endfed wires that use some kind of tuning to achieve a 50. I have inserted two additional links for coverage on 17m and 30m.
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