Ocf antenna hamwaves windom antenna dj2kt windom antenna. Here is a simple antenna calculator for two popular forms of ham radio hf wire antennas. Resources listed under windom category belongs to antennas main collection, and. Vertical dipole since i had purchased the kenwood ts590 transceiver a few months before i got my license, i needed an antenna or antennas right away for listening on the ham bands. The copper colored line is the inverted vee configuration. Antenna calculator for hf antennas ham radio secrets. Buy ocf dipole 7 band 806 meters antenna polystealth 61 core. The antenna calculator above uses this formula as a starting point to calculate wire lengths for the dipole. The apex of the antenna is hung from the peak of my roof. In other words an 80meter windom 7 feet long would have one leg 45.
Thus i set out to design an hf antenna with a vswr of 3. This antenna can be angled anywhere in a range from 0 as a halfwave vertical dipole, to 90 as a flattop horizontal dipole. A halfwave dipole is usually fed at its center because this is where maximum. Lets see some antenna calculator and antenna design software that will help you design faster and better. An additional reason will be given in the section about centerloading. On the other hand, an ocf dipole is an ungrounded dipole antenna fed with twinconductor line, either coaxial or open wire parallel conductors. Nvis antenna information near vertical incident skywave nvis antenna w0ipl commercial windom ocf antennas balun designs baluns maxcon antennas. This is part one of a multi part article dealing with setting up a sdr as a rfi site survey tool to assist in rfi detection, location, and mitigation. In summary, offset feeding causes the antenna to be loaded differently. The antenna has worked very well for me, and i have worked much dx with it. Update, i have been using this antenna with ft8 software.
The measurements below are for building a simple dipole antenna. Enter the desired operating frequency in megahertz to get a good starting length for a dipole in both feet and meters. An off center fed ocf dipole fed at the 23 point is resonant based on total length, and instead of a 75 ohm feed point they have anywhere from 200 to 600 ohms. Buckmaster ocf dipole antennas dxocf free shipping on. There will be standing waves on the coax but not extreme if we select the correct offcenter location. The normal windom is described as having a length leg, and a 23 length leg. The shorter wire is 44 feet long and is supported at the apex height of 25 feet by a birch tree in the front yard. The coax jumpers made the other 2 unactive elements. Ocf antenna hamwaves windom antenna dj2kt windom antenna from ja7kpi windom antenna sv1bsx windombalun winding instructions windom antenna the carolina version windom off center feed w8ji. Resources listed under ocf antenna category belongs to antennas main collection, and. It was written for dos many years ago and ported to windows. A commercial antenna system, the buckmaster 7band ocf dipole. After spending some time modeling ocf antennas, the closest antenna i could find to a true multiband dipole with reasonable swr on most bands had an 80%20% leg length and 200ohm feedpoint.
Ocf4010e3k ocf antenna windom this is an ocf dipole wire antenna also known as windom antenna fed at 19% from one end. These ocfs are offered to operate in 4, 7, or 8 bands. Study of the off centre fed dipole antenna g8ode short long feed point the off centre fed halfwave dipole the offcentre fed halfwave dipole, more commonly referred to as the ocfd, is very popular because it offers good performance as a multiband antenna using an antenna matching unit in conjunction with a 4. Ocf 4010e3k ocf antenna windom this is an ocf dipole wire antenna also known as windom antenna fed at 19% from one end. Placing the feed point away from the center, increases the resistive part of the feed impedance and source load more than the reactive imaginary part of the resonant antenna, which is nearly resonant. This calculator is designed to give the horizontal length of a particular dipole including tees antenna, or one side of it, for the frequency chosen. With the proliferation of personal computers and affordable even free software, antenna modeling has become a popular amateur activity.
However, any ocf dipole easily outperforms aforementioned obtrusive antenna arrangements. Force 12 fpa20ocf vertical running through 8 to 6 meters. It is a halfwave long on the lowest frequency, and is fed from a coax cable through a transformer inserted in the wire at onethird from one end. A wellconstructed 7 band offcenter fed dipole, designed for 7580, 40, 20, 17, 12, 10 and 6 meters. Feed line usually 50 ohms is connected at feedpoints, center conductor to one side, the shield to the other side of antenna. The interesting thing is that it is multi banded with no traps.
Thats one of the compromises that allows the ocf to have reasonable swr on the other bands. This is a common antenna configuration in the world of amateur radio referred to as a sloper or more accurately, halfwave sloper. Antenna modeling used to be the domain of scientists and engineers with very expensive antenna ranges covering acres and acres of land strewn with expensive equipment. Distance from center of antenna to the center of the coil in feet must be less than half the total antenna length given above. Please post a comment if you know other great software or links with information about antenna calculator and design programs. If your are serious about playing with the design of the ocf antenna on your own, do yourself a favor and invest in a good antenna analyzer which can scan the hf spectrum. The radiowavz dx ocf windom is a off center fed ocf dipole antenna that exhibits outstanding performance on all bands.
This antenna beams into three quadrants without the use of a rotator. Off center fed dipole installed and written april, 2007. Offcenterfed dipole antennas category is a curation of web resources on, ocf dipole, the six meter ocf sleeve dipole vertical, centerloaded offcenterfed dipole 6 band. Fd4 80402010 m the 4band fritzel model fd4 is a special version of a windom antenna. The 8band 300 watt antenna weighs 10 pounds and the 8band 3,000 watt antenna is 12 pounds. When running frequency sweeps, linear or logarithmic style swr, gain, fbratio and impedance linecharts are produced. This is a popular antenna design as the performance is very good across the hf bands and requires little or no tuning. Pvc coated wire, with every copper strand tinned to prevent corrosion. The operating cash flow is calculated by summing the net income. Feedline losses will be very reasonable with lowloss coax no rg58 please and using a goodbalun up at the antenna feedpoint. The radiowavz dx ocf windom is ideal for those of you who do not use a tower and beam. Over the years i have spent a great deal of time getting things tuned as i want them, putting a large, 40 radials, radial field put in place, and getting the antenna exactly. Over the past few years i have been using a hustler 6btv vertical antenna as my primary antenna for 80, 40, 30, 20, 15, and 10 meters.
Featured antenna from kai siwiak, ke4pt off center end fed dipole 6m 40m intended use for apartment dwellers and mobile deployment. Using eznec, the design of an ocf dipole allows many variations in overall antenna length, height and feed point to achieve the desired result. I usually build my own wire antennas but after seeing one at k4brs qth,i knew that i couldnt match the quality of the w8amz. Sold by crs communications and ships from amazon fulfillment. Enter the desired frequency and select the desired calculation from the drop box. The antenna is designed to be fed with 50 or 75 ohm coax cable of most any length with a balun. The 4band antennas are ocf offcenterfed, with a 23 foot leg and a 45 foot leg, totaling 68 feet. This is a first reason why it pays off to build your ocf dipole with 80 m as the fundamental wavelength and not, for example, 160 m. I run 4nec2 flawlessly on gnulinux using the equally free playon linux software.
Magnetic loops from the experts dj3tz n5izu py1ahd helically loaded magnetic loop antenna tower information towertalk. The long end of the antenna is 89 feet long and runs into the back yard. We have tested the new fpa20focf with a ldg at200proii autotuner rated for 6 to 1,000 ohm loads at the end of 40 feet of coax to simulate a typical installation and also with an mfj998rt outdoor rated tuner rated for 12 to 1600 ohm loads placed near the antenna. Heavy duty stainless 14 inch center threaded, cemented with lock nut eyebolt supports. By using relays, a single feed line could be switched to 1 of 3 elements or to all for an omni position. Program good for 1 500 mhz, although intended for mf hf useage. Its also ideal for those who want a high performance antenna with world class dx coverage 80, 40, 20, and 10 meters.
Works on all bands with an antenna tuner and performs. It is useful for measuring the cash margin that is generated by the organizations operations. The modern common windom antenna is not an original singlewire fed windom, but rather an offcenterfed or ocf two wire feed dipole. The offcenterfed dipole antenna design squash practice. Superb design no tuner, quality manufacture and booming all band signals. Buckmaster antennas are shipped ready to go with no trimming or assembly required. Quickly switch bands and eliminate a tuner as one more thing to adjust or transport. We have tested the new fpa20f ocf with a ldg at200proii autotuner rated for 6 to 1,000 ohm loads at the end of 40 feet of coax to simulate a typical installation and also with an mfj998rt outdoor rated tuner rated for 12 to 1600 ohm loads placed near the antenna. A halfwave dipole is usually fed at its center because this is where maximum current occurs. The short end was placed at about 40 feet off the ground, tied to a tree limb, using about 10 feet of insulated rope. The other antenna was made by antenna specialist who are still in business and may still produce the super scanner. Offcenterfed dipole, ocfd, windom, whereas a dipole is a halfwavelength long radiator, fed in the center of two equal length legs, the offcenterfed dipole which i prefer to call a windom is a dipole whose feedpoint is at a point removed from the center of the antenna the picture above on the left shows the classical dipole, which is usually fed with 50 ohm coax, through a 1. To accommodate the four bands, the overall length of the antenna 20. Feedpoint impedance of the antenna at that height on 80 will be about 3040 ohms before adding the 4 to 1 balun.
Such a problem can be solved by mounting a dipole at a slope. The ocf dipole is a compromise design hf antenna which allows operation on several bands without using an antenna matching unit atu. The inverted vee is is just a lazy dipole that cant hold its arms up and is about 4 to 5%. The effect is most pronounced at the fundamental frequency. I have the antenna in an inverted v configuration, the center being suspended from a oak tree limb at 37 feet. This app does nothing more than the standard 468freq mhz type calculations.
Wanting to discuss ocfds and singlewirefed windom antennas. Buckmaster ocf antennas work mutiple bands and are made from the best. Operating cash flow ocf is a common financial measure to determine whether the company is able to achieve the required cash flow to grow its operations. Antenna, ve3sqb ham radio antenna design software programs.
Right triangle angle and side calculator ve3sqbs antenna design programs w4neq doublet info. The socalled ocf windom is also a misnomer, for the same reasons. The 7 band ocf dipole antenna was erected at 25 to 30 feet, on a hill side, using a military style push up mast, with a few customization on it. This design is based on calculations from a program created by walter lau. The long end was tied to a tree, again, using insulated rope, and with maybe five. The results are conveniently displayed in inches, centimeters, feet and meters. Choose from ocf, vertical, loops, zepps, end feds using palomar engineers overengineered to outperformtm impedance transformers and feed line chokes for outstanding antenna performance. With the proliferation of personal computers and affordable even free software, antenna modeling has become a. In all cases 15m and the warc bands will require a tuner. View antenna display, showing the wires making up the model of the fiveelement beam, with currents and 2d slice superimposed to show orientation.
The blue line in the drawing is the example of a horizontal dipole. Windom antenna links category is a curation of 28 web resources on, i7swx windom antnena, offcenter fed windom antenna with vertical radiator, the coaxfed windom. The te11 cutoff frequency should be lower than 2412 mhz and the tm01 cutoff should be higher than 2462 mhz. This formula to obtain the length of a halfwave dipole antenna will give a good ballpark value to start with. Buckmaster ocf antennas are made from the best quality materials and are designed to give you years of troublefree service. The windom is just a horizontal halfwave of wire on the lowest frequency of. This calculator uses a k multiplying factor value of. Classic ocf antennas, like these, are typically fed with a 23 and offcenter ratio. This is a popular antenna design as the performance is very good across several. Describe your experience with the buckmaster 7 band, 300w, ocf dipole antenna and tell us why you give it the rating you did required.
A very basic program for calculating the length of each leg of a 12 wave wire dipole antenna. 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. Dipole antenna length calculator dipoles antennas are easy to build and can be very effective when placed half a wavelenth or more above ground. Total length of antenna in feet open the dipole length calculator in a separate page. Windom, w8gz who first published details of his antenna design in 1929. Buckmaster ocf dipole antennas buckmasters best coaxial cables antenna support rope harken stainless steel pulleys stringliner reel with 270 feet of twisted nylon line antenna wire screwon cablewire clamps linegrips rf chokes cq magazine archives great circle azimuthal equidistant maps world prefix and worked all states was maps hamcall. This means that the bottom of the antenna is 14 wavelength above ground. It all started with the windom antenna windom antenna the windom was once a very popular multiband antenna. Download hf dipole calculator 12 wave wire dipole antenna. The list will grow with your help so lets start and share the knowledge. If you have no particular preference within a given ham radio band, then simply enter its center frequency i.
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