The jpole is a slim, omnidirectional, halfwave antenna fed at the end through a quarterwave shorted transmission line. Theyre common in tv broadcasting, the skin of aircraft and in radar, microwave and cell phone applications. Kf4eoks 2 meter super jpole antenna build super jpole for 435mhz by vk6ysf the world wide web prepared by paul howarth vk2gx. This jpole is a balanced antenna going into an unbalanced feed line and can cause rf. Neverteless, it makes a great antenna for emergency or on the cheap. The dbj1 is easy to construct using inexpensive materials from your local hardware store. Mfj1736 sixmeter rollup jpole antenna introduction the mfj1736 was designed for fixed or portable sixmeter fm operation. If you like building good antennas, this one is for you. A fractal antenna has a few unique attributes as seen in this definition from wikipedia. The original idea comes from the zepp antenna which was developed for use on the german led. Good to get the antenna at least 10 feet off the ground. The design of this 6 m dipole antenna shall include the following design considerations. Pdf modified fractal super jpole antenna researchgate. A copper pipe jpole antenna is a single band antenna that is much like a.
This link is listed in our web site directory since monday oct 11 2004, and till today jpole theory has been followed for a total of 29983 times. When correctly installed, your antennas resonant frequency should. Using this type of antenna can be a bit tricky, so g. Built first antenna making it stealth black wire and black poly rope remove center rope support camo paint for the pvc pipe grey electrical box for coax may be adding a 1. Kb9vbr jpole antennas amateur radio, land mobile, scanner, low power fm, and airband antennas. A practical approach to hf and vhf antennas, plus antenna. I will not get into the theory or math in volved in the construction of this. I dont even feel comfortable trying to make just a monoband j pole using the twin lead. A discussion of antenna theory by paul graham k9erg j pole calculator and drawing by k4abt g. Aug 19, 2015 these agree well with the real jpole and 2bcx antennas measured in a real antenna test chamber in figure 2. The result is essentially an endfed dipole which exhibits more gain and a lower take off angle than the traditional halfwave dipole. This link is listed in our web site directory since monday oct 11 2004, and till today j pole theory has been followed for a total of 29983 times. The jpole antenna, more properly known as the j antenna, was first invented by hans. Antennas antennas couple propagating electromagnetic waves to and from circuits and devices, typically using wires treated in section 3.
Generally people dont think of radiofrequency radiation in terms of discrete. Ive made a few j pole antennas over the past few years, and they work great on the vhf and uhf bands. The mast and coax is generally vertical and as high and clear as the actual thing we think is the antenna, and so unwanted radiation from the feedline is quite apparent and part of the reason that the jpole sort of works. Pdf comparative analysis of slim jim antenna for ham radio. In radio engineering, an antenna is the interface between radio waves propagating through space and electric currents moving in metal conductors, used with a transmitter or receiver. If you decide to make a 2m antenna, youll end up with 1. About jpole theory the resource is currently listed in in 2 categories. Just enter the operating frequency and calculate the dimensions of your j pole antenna. Simple j antenna that will more than double your 2 meter and even 440 performance. Hf radio qrp ham radio antenna tech hacks all band circuit diagram electrical engineering bands radios. Navigation kb9vbr j pole antennas amateur radio, land mobile, scanner, low power fm, and airband antennas.
Works well with handheld ht radios, base stations, and repeaters. The first thing i would like to discuss is a little history, theory, and uses for fractal antennas. The jpole can be cheaply, simply and quickly constructed using a variety of techniques, some of which are discussed in this article. Experiment, create you own unique designs the j is a very forgiving, yet. The j antenna goes back many years, long before i became a ham. How to make a fractal antenna for hdtv dtv plus more on.
I had already successfully constructed a 2meter j pole, so why not apply the same concept to a 6meter version. Quick repairs to the diamond were out of the question. An inefficient antenna produces a smallamplitude em wave for the same feed power, and converts most of the power into heat. Ruggedly constructed one piece design, this jpole antenna will last practically forever. One of these days, ill make a j pole antenna for 20 meters. In this paper a super j pole antenna with two modified fractal koch curve shaped elements is proposed. The main category is j pole antenna plans that is about building jpole amateur radio antennas. We hang ours from some string thrown over a tree branch. A read is counted each time someone views a publication summary such as the title, abstract, and list of authors, clicks on a figure, or views or downloads the fulltext. Kb9vbr jpole antennas amateur radio vhf and uhf antennas. First discovered back in 1988 by nathan cohen and later published and patented in 1995. Hand crafted in the usa since 2001 and thousands of satisfied customers nationwide.
Despite its light weight and simplicity, the jpole is a timeproven design that radiates efficiently and exhibits low vswr. Claims of gain from 1 to 5 db are seen in writeups, but are not substantiated by sophisticated measurement and good theory. The j pole antenna is an omnidirectional, halfwave antenna fed via a quarterwave matching stub. How to make a fractal antenna for hdtv dtv plus more on the. The main category is j pole antenna plans that is about building j pole amateur radio antennas. These files are copywritten by the arrl and are public domain. Building a 2meter jpole antenna this jpole is made for 146 mhz. Mfj1736 sixmeter rollup j pole antenna instruction manual 1 mfj1736 sixmeter rollup j pole antenna introduction the mfj1736 was designed for fixed or portable sixmeter fm operation. Slim jim is a special wire antenna which has impedance selectivity of 50. J pole antennas should give you about 3 db gain over a monopole antenna. Many antennas are based on halfwave dipoles fabricated from wire or tubing. The antenna shall be supported from a single point at its center.
Buck rogers sr practical antenna handbook by joseph j. Kb9vbr j pole antennas are highly effective, affordable antennas for the vhf and uhf frequency spectrum. The dynamics of antenna design, the jpole antenna revisited yet again. Copper pipe jpole antennas by rory eikland, kg6hcu and ken larson, kj6rz rory and i have had excellent experience building and using jpole antennas constructed from 12 inch ridged copper pipe, so we decided that we would share our experiences. Try not to place the antenna close to any metal objects as well. These are preliminary notes, intended only for distribution among the participants. Ham radio antenna antenna tv communication methods dipole antenna all band electronics projects calculator slim how to plan. It does not need a ground plane, radials or a complicated matching system. Buck rogers, sr k4abt for this ultra simple, easy to understand j pole antenna calculator for hf, vhf, and uhf amateur radio bands.
Trailed behind the airship, it consisted of a single element, one half wavelength long radiator with a quarter wave parallel feedline tuning stub. Being one who enjoys a challenge, i set out to try. Tame the predictable mast currents found in any j pole antenna grounding conductive mast using a simple stub. Macgyver would be pleased with its foundmaterial construction. Despite its light weight and simplicity, the j pole is a timeproven design that radiates efficiently and exhibits low vswr. The vhf dipole antenna at vhf and uhf, most antenna systems are derived from the dipole or its complement, the slot antenna. One of the fractals used in antenna theory and design to. About j pole theory the resource is currently listed in in 2 categories. The jpole antenna consists of a halfwavelength radiator fed by a quarterwave matching stub. Understanding practical antennas and design for something that is often so simple to make, an antenna is remarkably difficult for many people to understand. Pdf in this paper a super jpole antenna with two modified fractal koch curve. In transmission, a radio transmitter supplies an electric current to the antennas terminals, and the antenna radiates the energy from the current as electromagnetic waves radio waves. Pdf file, 100 kb antentop012007, p 39 download pdf file.
Kb9vbr jpole antennas are highly effective, affordable antennas for the vhf and uhf frequency spectrum. For 2 meters, the coil is 4 turns of coax at 5 inches in diameter. In order to increase the bandwidth and to provide proper phasing of the currents in the. Ictpituursi school on wireless networking for development the abdus salam international centre for theoretical physics. At this point its pretty crystal clear fred judds 2bcx slim jim antenna doesnt offer anything special compared to a traditional jpole antenna. Building j pole amateur radio antennas category is a curation of 86 web resources on, j pole antenna for your packet radio station, the j pole antenna revisited yet again, j pole antenna for 6 meters. The jpole antenna is an omnidirectional, halfwave antenna fed via a quarterwave matching stub. Mom solution of hallens or pocklingtons integral equations antenna impedance models. In this paper a super jpole antenna with two modified fractal koch curve shaped elements is proposed. Ictpituursi school on wireless networking for development the abdus salam international centre for theoretical physics ictp, trieste italy, 5 to 24 february 2007. That assumption proved to be correct as i have received letters from a wide variety of people.
Jpole antennas ham radio, ham radio antenna, antennas. Copper dualband super jpole antenna by ka0nan, april 1993. The ugly macgyver 6 meter jpole the need so what do you do when a strong wind storm finally topples your nice diamond gh6 58 wave 6 meter antenna and you want to check into the 6 meter net the next day. Jpole antennas are said to have greater lowangle radiation and gain versus a halfwave dipole. The feed point is usually placed at the centre of the dipole, for although this is not absolutely necessary, it can help prevent. J pole antenna dbj1 a vhfuhf dualband jpole antenna, pdf file. Tame the predictable mast currents found in any jpole antenna grounding conductive mast using a simple stub. The yagi, jpole and nvis dipole and a glance at antenna design using 3d em software brian mileshosky n5zgt high desert amateur radio club 15 feb 20.
Apr 30, 2017 the national film board of canada for the canadian air forces great explanation of propagation. Copper pipe j pole antennas by rory eikland, kg6hcu and ken larson, kj6rz rory and i have had excellent experience building and using j pole antennas constructed from 12 inch ridged copper pipe, so we decided that we would share our experiences. Pdf ham radio applications demand antenna design with an aim of achieving maximum gain, which is affected by. On most of the j pole designs out there, a choke should be used as close to the feedpoint of the antenna as possible to help prevent rf on the feedline and creating difficulty with swr readings. Electromagnetics and antenna engineering basics dipole impedance by antenna theory. An efficient resonant antenna 14 wavelength or longer produces a largeamplitude em wave for a given feed power, and produces little heat. The success of the three previous editions of practical antenna handbook has been most gratifying. The design criteria begins by stating that the jpole is an endfed vertical halfwavelength antenna also known as an end fed zepp, that is matched to the transmitter output impedance by a series tuned section of transmission line. The national film board of canada for the canadian air forces great explanation of propagation. Shown is empirical evidence why this is a problem and a very simple solution all future grounded j pole antennas should incorporate. Oldest and simplest form of antenna di two pole voltage polarity usually 12wavelength long similar to a vibrating strings fundamental current maximum in the middle voltage maximum at the ends pattern repeats every 12wavelength direction or amplitude is reversed 20. Building jpole amateur radio antennas category is a curation of 86 web resources on, jpole antenna for your packet radio station, the jpole antenna revisited yet again, j pole antenna for 6 meters. Most people make these for 2m use, but you can make them for 70cm use if required. That means that mounting a two meter jpole at the top of a 10 foot pole will place the center of the radiating part of the antenna at about feet.
An introduction to amateur satellite ground station antennas. Slot antennas are familiar in the commercial radio world, but not to hams. The jpole antenna is an omnidirectional antenna that can be used for base, mobile and field day stations. All amateur radiorelated projects, tips, tricks, and tools.
A copper pipe j pole antenna is a single band antenna that is much like a. Well just call it a choke and not put everyone to sleep with a long discussion of antenna theory. A2 dipole adjustment required to change resonant frequency 43 fig. Its predecessor is the famous zepp antenna developed for the zeppelin airship.
The jpole is one antenna that probably should not have a balun for the above reason, should you decide to try this poorly conceived antenna. These are downloadable open file and use the save button in pdf reader. As a scanner antenna non transmit it is usable from 30 mhz through the gigahertz bands. Both antennas have served many hams around the globe well. Ed fong ed fong wb6iqn gives vaca valley radio club a presentation via skype. The j pole antenna, more properly known as the j antenna, was first invented by hans beggerow in 1909 for use in zeppelin airships. In the case of the jpole without radials, all of the common mode current created by the poor feed system flows over the coax shield and mast. Shown is empirical evidence why this is a problem and a very simple solution all future grounded jpole antennas should incorporate. A slot antenna is a narrow rectangular opening in a large conductive surface, such as a tv satellite dish. Their performance at a specific site is unpredictable because the jpole antenna interacts with nearby objects like the coax, mast, tower. The receiving properties of antennas are characterized by the antenna affective area af,t,i, where the available power at the output of the receiving antenna prf is the product of the effective area of the receiving antenna in direction t,i and the flux density swm2hz1 incident from that direction.
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