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. The antenna tuner is a 1977 heathkit hft9, a small qrp size tuner of the capcoilcap doublel design. The pomona box originally had a jack bnc connector on one end and a plug bnc on the other. The results are conveniently displayed in inches, centimeters, feet and meters. In the graph below i have plotted what mininec predicts for the impedance of an end fed half wave antenna versus the counterpoise length. 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. In early 2014 i conducted an online survey for portable antennas. 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. One short wire is rarely sufficient, unless maybe if you only operate one band. Feeling a bit too lazy to calculate that by hand, however, i wrote a program or two to do all. 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. That also means the antenna has to have a transmission line.
It is 148 foot of wire about 40 feet above ground between 2 tall trees. There have been many manufactures over the years that built half wave vertical antennas that had only a few short radials. 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. The main category is endfed antenna that is about endfed antenna projects and plans. I have documented some of the earlier ones i built in my pedestrian mobile pages. 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. Here is a simple antenna calculator for two popular forms of ham radio hf wire antennas. The following program will calculate the lengths needed to construct several popular wire antennas. My favorite antenna for portable use is the end fed halfwave or efhwa. However, it needs a tuner to get the swr low enough on some bands. Radio waves behave very similar to the photons in light waves. The design seemed relatively simple to build, requiring only a single toroid and a capacitor made with a. The main category is efhw end fed halfwave antenna that is about efhw end fed halfwave antenna. About efhw vertical antenna the resource is currently listed in in a single category.
How to create a counterpoise for an efhw antenna is hotly debated. Ive posted about endfed, halfwave antennas before, but until this weekend, id never built one. Aa5tbs excellent page for efhw info or, addressed below, to cut the wire so that it is not. 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. Some simple maths is required to calculate the magnitude of the voltages at the end of the efhw. A halfwavelength radiator has a high impedance high voltage, low current at the feedpoint. In figure 4 below can be seen how the impedance red line falls from around 70 ohms, to 50 ohms at 0. Unlike many end fed antennas on the market, this one does not require the antenna tuner to. This gave the antenna more gain than a simple quad. Using the technique of your choice, support the other end from a tree or other tall support. The solution to this problem is to provide a counterpoise close to the antenna, which is low impedance on all bands of operation. When you design a coupler for this antenna it helps to know what turns ratio you should use. For this application i removed the jack and installed a banana plug jack. 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.
Keep in mind the above is from measurements, not simulation. A couple of months ago, i ran across a design rated at 100 w. Describe your experience with the efhw8010 8band end fed half wave antenna and tell us why you give it the rating you did required. If it doesnt then the 5 band efhw is better as it can be built to need no tuner on the 5 bands.
Describe your experience with the myantennas efhw8010 antenna and tell us why you give it the rating you did required. See more ideas about cable options, mp3 player and ham radio. One is an efhwa for 2040 meters, and the other is a matching unit for the antenna. Mfj1984mp endfed 12 wave 300w 40m10m wire antenna 66 feet. Mar 09, 2010 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. 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. It is the sum of the antenna and ground electrode input impedances as modified by the length of the grounding strap. All you need to do is enter the desired resonant center. Rf antenna calculators for various antenna designs back to telecommunication.
This page contains various javascript based calculators for electronics. Wire antenna calculator amateur radio ham radio station ws6x. 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. This calculator can be used to design a quarter wave ground plane antenna, with radials. The very valid reason for this is that the high impedance of the feedpoint was outside the range of most transmitters and external tuning units. 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. Being able to feed the dipole from one end gives you more options on how to erect an antenna and makes. To this day, differential equations, integrals and specialized software are how engineers design bridges and arches. But performance is down about 812db on a dipole on. The antenna calculator above uses this formula as a starting point to calculate wire lengths for the dipole. For most hams, an endfed antenna is and endfed, halfwave, or efhw, antenna. Kb6nu finally builds an endfed, halfwave antenna kb6nu. The survey asked just one question what is your favourite portable antenna.
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. Link end fed half wave antenna and tuner for sota get out. The endfed halfwave efhw why is it the worlds most popular portable antenna. Efhw antenna without a counterpoise may well give rise to problems of various.
Setting out to explore the world out of efhw antennas that have dominated the discussions nowadays. May 29, 2017 comparison between the efhw and dipole on 20 meters. Antenna, ve3sqb ham radio antenna design software programs. The free mmanagal software has a built in trap calculator. 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. Unlike many end fed antennas on the market, this one does not require the antenna tuner to operate. End fed half wave antenna coupler efhw m0ukd amateur. 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. Attach one end of your antenna wire to one of the binding posts, either directly or using a jumper wire. 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. Mar 19, 2018 this is the best wire antenna i have tried. Dipole antenna ham radio antenna good communication calculator wire radios hams workbenches circuits.
Qrp multiband hf efhw antenna for sota post updated 29 september 2017. I found that the counterpoise connection was not really needed and the switch that connected the transceiver ground to the counterpoise ground. Since i enjoy using end fed half wave antennas so much i built a small coupler to use with my rockmite. If you have no particular preference within a given ham radio band, then simply enter its center frequency i. The efhw end fed half wave needs to be classified as a specific case of the class of end fed wire antennas. This is a presentation i gave at norfolk amateur radio club. The g0kya efhw an endfed half wave monoband hf antenna. The wavelength calculators used to calculate the antenna element dimensions will therefore use the speed of light 299792458 meters per. Obviously, an efhw antenna has a halfwave length only at one specific frequency. Expect a 12 s point improvement over a quarter wave or trapped vertical. The antenna tuner will load an end fed long wire effectively, especially if it is cut to aprox. Stainless hardware, uv resistant materials throughout. Efhw8010p 200w portable or stationary multiband end fed half wave antenna.
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. So, a multiband endfed halfwave antenna is actually a bit of a misnomer. 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. Efhw 8010p 200w portable or stationary multiband end fed half wave antenna.
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. 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. Full hf coverage, no tuner needed on most frequencies. Coinductive and pdlii are trademarks and this antenna is most certainly covered by patents. Simulations suggest what feedline lengths to avoid and offer a confirmation why portable users with short feeds never seem to have trouble. The antenna is designed to be fed with 50 or 75 ohm coax cable of most any length with a balun. The rationale behind this was not to find what people thought was necessarily the bestperforming portable. Method of moments technique to calculate steady state currents of each wire segment. A special case of this, is the endfed halfwave efhw antenna. 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. As typically installed, it is a compromise antenna but great for portable use because it is easy to pack and easy to install. Endfed wire antenna lengths amateur radio stack exchange. A few years ago i built a little rockmite transceiver for 40m.
At opposite ends of the software landscape we have. Random wire antenna lengths university of delaware. The loops of folded antenna have been replaced by v shaped elements without any changes and easier matching. Endfed antenna for qrp portable ops ham radio site. No long counterpoise, radials or feedline required. All you need to do is enter the desired resonant center frequency in the form below, then click calculate. About the efhw antenna the resource is currently listed in in a single category. As the counterpoise itself approaches a half wavelength, the impedance approaches 5000 ohms. The endfed halfwave antenna can function alone, but feed lines are the norm regardless. Habits born form the use of centerfed halfwave antennas do not apply to the endfed case but they almost do.
A socalled random wire antenna is an end fed antenna. 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. Efhw antennas might have elevated swr readings on some bands due to the different position, height above ground or impact from nearby objects. 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 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. 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. Antenna calculator for hf antennas ham radio secrets. The measurements below are for building a simple dipole antenna. 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. There are usually four radials, three being a minimum, but you could use up to six. This formula to obtain the length of a halfwave dipole antenna will give a good ballpark value to start with. End fed antenna ideas antenna, ham radio antenna, ham radio. A shortened multiband endfed half wave efhw antenna.
You cant, for example, generally use a 40m efhw antenna on 20m. Does a 12 wavelength endfed antenna need a good rf ground. A shortened multiband endfed half wave efhw antenna for. I havent done the calculations, but as built, id guess that its good up to. This is an endfed halfwave efhw antenna for 80403020171512 and 10m bands.
Endfed half wave efhw antenna modeling with mmanagal. Slim jim and jpole antenna calculator build a cactus for any frequency. While dipoles are very efficient antennas, they are not the only way to go. 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. This is a common antenna configuration in the world of amateur radio referred to as a sloper or more accurately, halfwave sloper. The coupler converts the high impedance end of the end fed half wave antenna down to 50 ohms. 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. Centre fed half wave dipoles make great, simple and effective antennas for the hf bands.
If you only have one support an endfed antenna may suit you better. This is a 200w version of popular efhw 8010 endfed halfwave efhw antenna for 80403020171512 and 10m bands. In the world of ham radio a straight dipole antenna is rare because wire sags and tubing droops. A multiband efhw may be better as it is not so dependent on an earth and the radiation maximum is higher up the antenna. Efhw end fed halfwave antenna category is a curation of 27 web resources on, 20m halfwave end fed, the efhw antenna, efhw matching unit.
The very valid reason for this is that the high impedance of the feedpoint was outside the. 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. As noted, this design is optimised for the 8015m bands. G0kyas hf end fed half wave efhw antenna construction. The mathematics to describe this catenary curve defied solution until calculus was invented. The g0kya efhw an endfed half wave monoband hf antenna, plus two multiband versions new.
One of the cautions you sometimes see in discussions of the endfed antenna are avoid multiples of a half wave. Antenna design calculators jeroen steeman software. The antenna then doesnt resemble the end fed wire that most people build. Antenna modeling suggests that the impedance is closer to 1800 ohms depending on the counterpoise length used. If you have a tuner, then the 8010 efhw is easier as it is lighter, smaller and less fragile given it has no traps. Mmanagal is a popular antenna design, analyzing and modelling software tool, that is relatively easy to learn and use. You can also l shape it or zig zag it or slope it if you are limited on room. 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.
But be warned endfed antennas can be noisier and also cause more emcinterference problems. Such a problem can be solved by mounting a dipole at a slope. In fact, it is tiny and you can run it on nothing more than a lithium battery. This antenna can be angled anywhere in a range from 0 as a halfwave vertical dipole, to 90 as a flattop horizontal dipole.
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. Most of the construction videos or sites teach how to make the 99. That post basically criticized the seller of the qso king antennas being sold on ebay. The latter is treated as a lowloss singlewire transmission line. I have found this calculation to work well, however it depends on many factors such as wire used, location etc. Endfed wire antennas radio society of great britain. Here are some other examples of the end fed half wave antenna. Aug 12, 2016 for the past couple of weeks, ive been playing with endfed wire antennas. Remote loading unit for a 160 end fed antenna, g4gys. I have inserted two additional links for coverage on 17m and 30m. This is a presentation i gave at norfolk amateur radio. The following table gives a few data points to consider. End fed half wave antenna coupler swr bridge, aa5b.
What hes selling isnt really what most hams think of when they think of an endfed antenna. Sometimes however, the centre feed is not ideal, for example when you want to use it as a vertical. 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. Comparison between the efhw and dipole on 20 meters. Unlike most devices for this job, the minivna pro has been built for portability. 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. Of late ive been using this antenna mainly with my kx2. Link end fed half wave antenna and tuner for sota get. There are operators who swear their center fed 12 wave dipole is 2 s points better than the efhw and vice versa. Ive been doing a lot of reading on the subject, especially aa5tbs excellent explanation of the theory behind a resonant efhw antenna.