Open Stub J Pole Calculator

If you need a "super" j, use a piece of 3/4" pvc as the insulator and add the stub and another 38 or so inches of conduit. If both sides of the open line are same distance from pole, you don't need to twist it. The SIMPLE 2m Copper 'J' Antenna : by KB9VBR on September 18, 2001 Mail this to a friend! The J is a great antenna. 0dB/100feet at 146MHz and 2. The quarter-wave stub is a transformer that provides a means of transforming the high impedance of the antenna to that of the transmission line. Page 1 of 2 1 2 Next > J-Pole Calculator for those do not own a personal calculator. See more ideas about Tower, Ham radio and Ham radio antenna. The Romex Dual Band J-Pole antenna project is completed. Every few monthes a group of us get together, invite the new hams and have an antenna party. 93 - Picnic. How to install the Pockrus J-pole (shopping list, tools, instructions by Noji) Arrow OSJ 146/440 2 m / 70 cm 1/2-wave open-stub J-pole ($49, see reviews and reviews and manual) 1000 W / 2. The J-pole antenna is an end-fed omnidirectional half-wave antenna that is matched to the feedline by a quarter wave transmission line stub. One-year paid ARRL membership Hug from Chad! Actually, a roll of paracord Thin Mints! Roll of Stretch-and Seal. Measurements and simulation confirm the quarter-wave stub modifies the circular H-plane pattern shape increasing the gain slightly on the side of the J Read Article. This calculator provides quick estimation of antenna size required for a given gain and frequency. DBJ-UHF was developed from a grant from AC Daughty to develop a low cost medium gain MESH antenna for UHF. I am using 14 awg THHN for the radiator and stub. I am a big fan of the J-Pole antenna style and have built a few of them in the past (see here and here). Instructions can be found on NT1K. Typical construction materials include copper pipe, ladder line, or twin-lead. How to install the Pockrus J-pole (shopping list, tools, instructions by Noji) Arrow OSJ 146/440 2 m / 70 cm 1/2-wave open-stub J-pole ($49, see reviews and reviews and manual) 1000 W / 2. 2M Ladder Line J-Pole Update: Since I wrote this, I've seen in several places that coil chokes are not effective on 2M & higher. There are many rumours on the Internet, claiming that the Slim Jim has better performance than the J Pole. Calderon, DU1ANV Makiling Amateur Radio Society (MARS) Way back in 1987, I was at the Zurich Airport, Switzerland, waiting for my plane ride back to. The calculator above will give you a good starting point, although spacing between the elements, velocity factor and other differences will have an effect on where this actually is. This arrangement turns a J-pole into a phased array. If you need a "super" j, use a piece of 3/4" pvc as the insulator and add the stub and another 38 or so inches of conduit. Relics: Radio communications: 11 m Band Super J-Pole antenna centred at 27. com Copper J-Pole Antennas by dxzone. I needed to add elements and his first calculator had that, but didn't show dipole length and his new one didn't allow for adding elements. -(Students: If the stub is open, what impedance does it stub. Due to material, I decided on a 5 element Yagi built for VHF since all I would have to buy is more 3/8″ round stock. This shows the general idea anyway. Demonstrate resonant 1 l J-pole. The Zepp, short for Zeppelin is any resonant antenna end-fed by ladder line. N3GO has a much more detailed description of the J-Pole antenna here. The Slim Jim, similar to the J-pole, is in fact a half wave end fed dipole, in the Slim Jim's case, an end fed folded dipole. I saw the plans for this on the internet (link to plans) by Allen Lowe (N0IMW). PDF | In this paper a super J-pole antenna with two modified fractal Koch curve shaped elements is proposed. still really cheap" Dave, WB5HDS. 1, I S S u e 1, S e p t e m b e r 2010 ISSN : 0976-8491(Online). 1 on ch 20, and 1. ImpedCalc is a free transmission line impedance calculator. then instructs to do the calculation on the linked site (which was a handy little tool). I found that the dimensions may vary from supplier to supplier by as much as 1/8 of an inch!. 220 MHz not only has repeaters but has become a. 3 on ch 20 and 1. Above is a connection of half-wave dipole antenna. The J-pole antenna is an end-fed omnidirectional dipole antenna that is matched to the feedline by a quarter wave transmission line stub. 5 meter of ribbon feed cable. The J-Pole makes a great base station and emcomm emergency communications amateur radio and scanner antenna. With twice the gain of a standard J-Pole antenna, the 2 meter Slim Jim antenna is a J-Pole on steroids! The Slim is an end-fed folded dipole antenna that has a gain of 6 dbi and a nice low RF take off angle. Invented by Fred Judd(G2BCX), the name was derived from its slim construction and the J type matching stub (J I ntegrated M atching). The following program will calculate the lengths needed to construct several popular wire antennas. The Zepp, short for Zeppelin is any resonant antenna end-fed by ladder line. The impedance of this antenna is around 300 Ω, so you may want to use a transformer or a λ/4 long piece of 120 Ω coaxial cable to match this impedance to 50 Ω. It approximates the series inductance as a high impedance transmission line while the shunt capacitance effect is simulated by an open-circuited stub using Richard’s transformation. Department of Agriculture Forest Service Forest Products Laboratory Madison, WI 53705 Abstract This committee meets on an annual basis to review andupdateitsstandards. The quarter-wave stub is a transformer that provides a means of transforming the high impedance of the antenna to that of the transmission line. This calculator can also be used to make the J-Pole. 1 Calculation. There are actually 3 transitions in a j-pole. As with all folded dipoles, the currents in each leg are in phase, whereas in the matching stub they in phase opposition, so little or no radiation occurs from the matching section. A balun is necessary because a J-pole antenna uses a balanced feed (the. A distributed-element filter is an electronic filter in which capacitance, inductance, and resistance (the elements of the circuit) are not localised in discrete capacitors, inductors, and resistors as they are in conventional filters. Basically, the 1/4 wave stub is shorted at the bottom, the feed point is adjusted away from the shorted end until a 50 ohm impedance point is found. The Open Stub. The antenna has an omnidirectional pattern with a low take-off angle. Phased arrays are often used in commercial and military installations. polebarnguru Post author September 3, 2012 at 1:06 pm. Relics: Radio communications: 11 m Band Super J-Pole antenna centred at 27. If both sides of the open line are same distance from pole, you don’t need to twist it. There are losses in the coil. There are actually 3 transitions in a j-pole. That is a good thing. PDF File here. "Buck" Rogers Sr (65 years as K4ABT) Between the articles by the late Lew McCoy W1ICP and myself, the J-POLE, Windom, and ZEPP should be around "forever. A distributed-element filter is an electronic filter in which capacitance, inductance, and resistance (the elements of the circuit) are not localised in discrete capacitors, inductors, and resistors as they are in conventional filters. The Wavelength is 11. Both are great antennas, I don't have a problem recommending either of them as the foundation for a amateur radio base station. I am looking at building an antenna something like the Arrow Antenna's Style J Pole's. 5:1 or better over the entire band. I saw the plans for this on the internet (link to plans) by Allen Lowe (N0IMW). The short tuning stub was 49. I've constructed a 144/440 Dual band Open Stub J-Pole Antenna. 2019- Utforsk denne tavlen til sverreholm på Pinterest: «Moxon antennas». There are times when you may need more gain than the standard J-Pole antenna. The Super-J is a J-pole with an additional 1/2 wave radiator attached to the end of a standard J-pole through a 1/4 wavelength phasing stub. ImpedCalc is a free transmission line impedance calculator. Since I had a Metal Fabrication background, I th… See more. A distributed-element filter is an electronic filter in which capacitance, inductance, and resistance (the elements of the circuit) are not localised in discrete capacitors, inductors, and resistors as they are in conventional filters. The center conductor of the coax is attached to the 3/4 wavelength section, while the. Further, it provides a solid mechanical base for the apex of the triangle. The ARRL Antenna Book describes two common configurations of the J-Pole antenna: an open-stub version and a shorted-stub version. I saw the plans for this on the internet (link to plans) by Allen Lowe (N0IMW). Bottom λ/4 parallel sections are the matching unit. I've constructed a 144/440 Dual band Open Stub J-Pole Antenna. Slim Jim vs J Pole. The coax or stub can then be attached to the connections in the terminal block and held securely. The J-pole antenna, also called the Zepp' antenna (short for Zeppelin), was first invented by the Germans for use in their lighter-than-air balloons. Made from 3/8" solid 6061-T6511 aluminum rod and 1. Slim Jim antenna calculator & Slim Jim information. STANDARD SPECIFICATIONS FOR WOOD POLES Ronald Wolfe, Research General Engineer Russell Moody, Research General Engineer U. then instructs to do the calculation on the linked site (which was a handy little tool). Matching to the feed-line is obtained by sliding the connection of the feed-line back and forth along the stub to obtain the voltage wave Standing Wave Ratio is as close as possible to 1:1 [4]. 00 Ham Radio Satellite Antenna Simple, inexpensive and lots of fun! Here is an easy to make home brew antenna that can get you on the air working satellites or be built for use as a portable hand held antenna to extend the range of your HT. If the AC current flowing in the series resonant circuit is I, then the complex power delivered to the resonator is C R jL j I Z I Pin in 1 2 | (4 |-1) 2 At resonance the reactive power of the inductor is equal to the reactive power of the capacitor. Trailed behind the airship, it consisted of a single element, one half wavelength long radiator with a quarter wave parallel feedline tuning stub. Electrically the J-Pole is a half wavelength antenna that is end-fed by a quarter wavelength stub to achieve a feed point impedance of 50 Ohms. Make the "j"out of 1/4" soft copper, Solder it in place thru the hole and add the cable. I am looking at building an antenna something like the Arrow Antenna's Style J Pole's. 146 MHz marker. Now it’s time to step it up (just a little bit) and fabricate a bigger antenna. This calculator can also be used to make the J-Pole. com J-Pole Dimensions at N6mrx Dual band - Open stub by Chuck W4CLL J-Pole with 5/8 wave section above 1/2 wave Roll-uP J-Pole Antenna at the Conejo Valley Amateur. I saw the plans for this on the internet (link to plans) by Allen Lowe (N0IMW). Slim Jim antenna calculator & Slim Jim information. In addition, it is required to provide an open-circuit condition at the third-harmonic component. I’ve constructed a 144/440 Dual band Open Stub J-Pole Antenna. Thick aluminum base plate. Online physics calculator that calculates the long, short section, feed point, spacing dimensions values for current frequency. I do not know the diameter or length of the coil but it must be under 1 mh. While I haven't built this particular J-Pole, I've constructed several using similiar plans. The basic j-pole antenna looks like this: J Pole (1/2 wave vertical antenna) diagram. VHF and UHF Antenna Systems 18-3 cable TV operators as "end runs"—pieces at the end of a roll. Transmission Line- Open Stub Transmission Line J-Pole- Super J-Pole- Log Periodic. Note that the stub is only an open-circuit at UHF, acting as a small inductance in-stead, at VHF. 5″ so I'd go at least 3x that for spacing away from a pole. where Zin is the input impedance seen on the rig side, Rload is the load or antenna impedance, and Zo is the Q-section's (Q is quarter wave) transmission line impedance. I believe that its because is mounted too close close to my open stub J-pole antenna for 2m/70cm. The J-pole antenna and its variations may be fed with balanced line. Coax can be used to match the J-pole as somewhere between the closed circuit and open circuit of the stub an exact 50 ohm impedance match exists. 3: ImpedCalc; ImpedCalc is a free transmission line impedance calculator. then instructs to do the calculation on the linked site (which was a handy little tool). The radiating part of the antenna starts above the tuning stub. (some say use 73 ohm coax) However, the high quality W2DU 1:4 current balun ( Catalog # W2AU4) was chosen instead because regular RG8x 50 ohm coax connected right to it and it was a faster setup than hassling with cutting and connecting a matching stub at the feedpoint. It includes below a calculator to work out all the mesurements for the frequency you require. STANDARD SPECIFICATIONS FOR WOOD POLES Ronald Wolfe, Research General Engineer Russell Moody, Research General Engineer U. This shows the general idea anyway. 1 Calculation. My name is Michael, KB9VBR, and I carry a full line of VHF and UHF antennas for sale. Free Online Engineering Calculator to quickly estimate the geometric Size of a J-Pole Antenna. As seen above, both the Slim Jim and traditional J-Pole antennas provide a measurable benefit to dipoles and monopole antennas using radials. Slim Jim antenna calculator & Slim Jim information. If both sides of the open line are same distance from pole, you don’t need to twist it. STANDARD SPECIFICATIONS FOR WOOD POLES Ronald Wolfe, Research General Engineer Russell Moody, Research General Engineer U. the beginning reads to use 1. The SIMPLE 2m Copper 'J' Antenna : by KB9VBR on September 18, 2001 Mail this to a friend! The J is a great antenna. Matching to the feed-line is achieved by sliding the connection of the feedline back and forth along the stub until a VSWR as close as possible to 1:1 is obtained. 0dB/100feet at 432MHz. I've constructed a 144/440 Dual band Open Stub J-Pole Antenna. Drill a 1/4" hole at the place where the "J" goes. The J pole has a quarterwave matching stub. The original idea came from the Arrow Antenna open stub J-Pole which is made and sold by Allen Lowe (NoIMW) for $39. 2 535 298 –W J Lattin (1950). Department of Agriculture Forest Service Forest Products Laboratory Madison, WI 53705 Abstract This committee meets on an annual basis to review andupdateitsstandards. Been going all over the place today. My name is Michael, KB9VBR, and I carry a full line of VHF and UHF antennas for sale. Both of these schemes are SWR patches, not fixes. Transmission Line Filters Beyond Stubs and Traps Steve Stearns, K6OIK 2003 Twin-Lead J-Pole Design Transmission line and stub properties. The radiating part of the antenna starts above the tuning stub. Figure 17 - Lumped LC Circuit Replaced with 1/4 Wave length Stub (End Fed Zepp) If you take this a few steps further you can see how the antenna evolves into a classical J-Pole antenna that is often used at VHF with good success (fig. 5:1 or better over the entire band. Slim Jim and J-Pole calculator | M0UKD Amateur Radio Station Information Page I've constructed a 144/440 Dual band Open Stub J-Pole Antenna. I confirm the mast’s propensity to draw current from the j-pole bottom and, using one of the solutions proposed above, confirm a way to mitigate it while still maintaining a dc path to ground. Wire Antenna Calculator. The Open Stub. VHF and UHF Antenna Systems 18-3 cable TV operators as "end runs"—pieces at the end of a roll. Less commonly available from CATV companies is the 3/4-inch 75-Ω. com, the spacing is 3. Sounds complicated, but it really isn't. The J-pole and other end-fed Hertz antennas are prime examples of antenna that can have severe feed line common mode current problems. Transmission Line- Open Stub Transmission Line J-Pole- Super J-Pole- Log Periodic. I've constructed a 144/440 Dual band Open Stub J-Pole Antenna. What can I do? A: Try adding a balun to the coax. Jensen has this one installed in his studio broadcasting on 88. The Copper Cactus J pole antenna design is a simple amateur radio antenna model that will allow you to operate both bands. In addition, it is required to provide an open-circuit condition at the third-harmonic component. I do not know the diameter or length of the coil but it must be under 1 mh. L-Tuner Simulator is a small, handy tool designed to help you calculate the input impedance of the L matching network, the impedance of the load (cables + antenna), or to find the Antenna impedance giving the cable length. There are many rumours on the Internet, claiming that the Slim Jim has better performance than the J Pole. >The Slim Jim / J-Pole is essentially just a halfwave, endfed via a >quarterwave stub (in HF terms, a "Zepp" antenna). Convert a J Pole to a Slim Jim More Antenna Projects!. com/osj/j-. Okay, enough of UHF/GMRS antennas. You’re better off using the extra copper pipe as a mast decoupling stub in the Mast Mountable J-Pole Antenna. And "inf" result means an open circuit stub impedance. A tabulation of mea-sured legs (W) and acceptable root openings (R) related. 85 - Backpack J-Pole Antenna for 10m, 6m, 2m. 54 I n t e r n a t I o n a l J o u r n a l o f C o m p u t e r S C I e n C e a n d t e C h n o l o g y IJCSt V o l. Wire Antenna Calculator. Most of us know a 1/4 wave stub or Q-section can transform impedances. Both open ends. Basically, the 1/4 wave stub is shorted at the bottom, the feed point is adjusted away from the shorted end until a 50 ohm impedance point is found. Department of Agriculture Forest Service Forest Products Laboratory Madison, WI 53705 Abstract This committee meets on an annual basis to review andupdateitsstandards. VHF and UHF Antenna Systems 18-3 cable TV operators as "end runs"—pieces at the end of a roll. Further, it provides a solid mechanical base for the apex of the triangle. It approximates the series inductance as a high impedance transmission line while the shunt capacitance effect is simulated by an open-circuited stub using Richard's transformation. The pvc ic cut 2 1/2″(6. I saw the plans for this on the internet (link to plans) by Allen Lowe (N0IMW). V-U Antenna J-pole bibanda - Benvenuti su OfficinaHF! I've constructed a 144/440 Dual band Open Stub J-Pole Antenna. I’ve constructed a 144/440 Dual band Open Stub J-Pole Antenna. I've constructed a 144/440 Dual band Open Stub J-Pole Antenna. The Zepp, short for Zeppelin is any resonant antenna end-fed by ladder line. Less commonly available from CATV companies is the 3/4-inch 75-Ω. Lots of considerations - first (and most important) chances are very good your roof system is not designed to support the weight of drywall. Second, half a wavelength of aluminum in the air whether a ground plane or an open stub j-pole will have virtually the same gain. My experience is that they may reduce your SWRs & make a more forgiving antenna - but this could be bad & good - so do a little research. Note: See Annex II for formula governing the calculation of effective throats for fillet welds in skewed T-joints. Figure 17 - Lumped LC Circuit Replaced with 1/4 Wave length Stub (End Fed Zepp) If you take this a few steps further you can see how the antenna evolves into a classical J-Pole antenna that is often used at VHF with good success (fig. Above is a connection of half-wave dipole antenna. The Super J Pole antenna is a co-linear vertical consisting of a number of half wave length vertical elements separated with half-wave length stubs (Tuning stub) feed with a folded matching stub. where Zin is the input impedance seen on the rig side, Rload is the load or antenna impedance, and Zo is the Q-section's (Q is quarter wave) transmission line impedance. 91 - Inductance-Loaded Shortened Dipole for 160m. As with all folded dipoles, the currents in each leg are in phase, whereas in the matching stub they in phase opposition, so little or no radiation occurs from the matching section. stub may be grounded directly. Open Stub J-Poles Photos of the OSJ 146/440. Thick aluminum base plate. Emmett ~ Thank you very much for your kind words. Department of Agriculture Forest Service Forest Products Laboratory Madison, WI 53705 Abstract This committee meets on an annual basis to review andupdateitsstandards. Randy's approach was a common one in ham radio: Let's just try it! We would try the J-Pole in the attic location first and see if the performance was acceptable in that. I’ve constructed a 144/440 Dual band Open Stub J-Pole Antenna. It includes below a calculator to work out all the mesurements for the frequency you require. I started around 5am and modified Chang Puak's Yagi-Uda calculator to suit my needs. I do not know the diameter or length of the coil but it must be under 1 mh. A two-pole Chebyshev bandpass filter is designed and tested at 1. With twice the gain of a standard J-Pole antenna, the 2 meter Slim Jim antenna is a J-Pole on steroids! The Slim is an end-fed folded dipole antenna that has a gain of 6 dbi and a nice low RF take off angle. Note that the Slim Jim has more gain at a lower angle, directed towards another radio at your same elevation. open end decouples that frequency from the main element 10 m ¼ W VERTICALS ¼ W Decoupling Stub Multiband A A B B C A C ½ W ½ W VHF/UHF Collinear (J-Pole Match) A different connection is possible -that is A to C. Typical construction materials include copper pipe, ladder line, or twin-lead. I saw the plans for this on the internet (link to plans) by Allen Lowe (N0IMW). Baofeng UV-5XP transceiver and a “Pockrus” Joystick dual-band open-stub J-pole, the grand prizes, which the club gives away at each meeting. Figure 17 - Lumped LC Circuit Replaced with 1/4 Wave length Stub (End Fed Zepp) If you take this a few steps further you can see how the antenna evolves into a classical J-Pole antenna that is often used at VHF with good success (fig. The coax feed point was about 5cm from the bottom. This results in an insulator action or decoupling B B A Patent No. Some Amateur Radio stations use high power 1500 Watt transmitters to bounce signals off the moon reflecting back to earth however others make worldwide contacts using. The club also gives away one paid one-year ARRL membership (new or renewal) at each meeting. Note: See Annex II for formula governing the calculation of effective throats for fillet welds in skewed T-joints. Baofeng UV-5XP transceiver and a “Pockrus” Joystick dual-band open-stub J-pole, the grand prizes, which the club gives away at each meeting. Stainless steel jam nuts and Workman SO-239 female feed connector. Here come the arguments as about half the designs attach to the. 1) An end-fed unbalanced half-wave to: 2) balanced quarter-wave stub to: 3) unbalanced feedline. A planar phased array is used on AEGIS class guided missile cruisers of the US Navy. This was. With twice the gain of a standard J-Pole antenna, the 2 meter Slim Jim antenna is a J-Pole on steroids! The Slim is an end-fed folded dipole antenna that has a gain of 6 dbi and a nice low RF take off angle. com Copper J-Pole Antennas by dxzone. Basically, the 1/4 wave stub is shorted at the bottom, the feed point is adjusted away from the shorted end until a 50 ohm impedance point is found. the hatchback of the vehicle to be opened with the antenna instaled, Fig 37. I saw the plans for this on the internet (link to plans) by Allen Lowe (N0IMW). 6 Meters for the Slim-Jim. Trailed behind the airship, it consisted of a single element, one half wavelength long radiator with a quarter wave parallel feedline tuning stub. Here is a step by step build of the Open Stub J-Pole Antenna. There are times when you may need more gain than the standard J-Pole antenna. 1 on ch 20, and 1. 0dB/100feet at 146MHz and 2. It is based on this production antenna. The improvement came today when I implemented an idea I had concerning the severed piece of wire that "just goes along for the ride" in. "Buck" Rogers Sr (65 years as K4ABT) Between the articles by the late Lew McCoy W1ICP and myself, the J-POLE, Windom, and ZEPP should be around "forever. I saw the plans for this on the internet (link to plans) by. Jensen has this one installed in his studio broadcasting on 88. Sounds complicated, but it really isn't. LinK 3 LinK 4 Calculator. still really cheap" Dave, WB5HDS. 0dB/100feet at 432MHz. 5″ so I'd go at least 3x that for spacing away from a pole. The formula is. N3GO has a much more detailed description of the J-Pole antenna here. That is a good thing. 2m 70cm Dual Band Open Stub Solid J-Pole : I make these antennas out of solid, aircraft-grade aluminum, no weak tubing! These antennas are welded, so they are strong, have low resistance between parts, are more efficient and zero maintenance! Put one up and use it for many years. 90 - Double-Delta Antenna 80m and 40m. ImpedCalc is a free transmission line impedance calculator. Electrically the J-Pole is a half wavelength antenna that is end-fed by a quarter wavelength stub to achieve a feed point impedance of 50 Ohms. Invented by Fred Judd(G2BCX), the name was derived from its slim construction and the J type matching stub (J I ntegrated M atching). 2m 70cm Dual Band Open Stub Solid J-Pole : I make these antennas out of solid, aircraft-grade aluminum, no weak tubing! These antennas are welded, so they are strong, have low resistance between parts, are more efficient and zero maintenance! Put one up and use it for many years. I dry fit everything together to check the measurements. N3GO has a much more detailed description of the J-Pole antenna here. Some swear by it but I am sorry , I have never heard one that worked that well. Need a general purpose antenna on ' 6 metres - the magic band ' ? The J-Pole is an easy-to-build and inexpensive device that provides an omni-directional vertically polarised antenna without the need for a ground plane. Aug 21, 2019- Explore jimmohney's board "Amateur radio", followed by 131 people on Pinterest. I started around 5am and modified Chang Puak's Yagi-Uda calculator to suit my needs. (some say use 73 ohm coax) However, the high quality W2DU 1:4 current balun ( Catalog # W2AU4) was chosen instead because regular RG8x 50 ohm coax connected right to it and it was a faster setup than hassling with cutting and connecting a matching stub at the feedpoint. Unlike to others, this notch is then matched to the source/load at the passband frequency. I believe that its because is mounted too close close to my open stub J-pole antenna for 2m/70cm. 1) An end-fed unbalanced half-wave to: 2) balanced quarter-wave stub to: 3) unbalanced feedline. the SIMPLE 2m/440 Copper pipe "J" by Dale "Kuby" Kubichek, N6JSX 03/2001&2008 Can you use a pipe cutter or a hack saw, can you solder - then here is how to build a SIMPLE "J" antenna that will more than double your 2 meter (and even 440) performance! The "J" antenna goes back many years, long before I became a ham. (radiator) section of the J -pole? Zig or Zag: Although there is not a big change in VSWR, let it be known! There is a pronounced (worse) difference in field intensity when the coax center conducted is attached the short stub of the J-pole; NOT GOOD! Without a lot of fanfare,. 54 I n t e r n a t I o n a l J o u r n a l o f C o m p u t e r S C I e n C e a n d t e C h n o l o g y IJCSt V o l. com Abstract The theory for a single band J-pole is first described. We will introduce the Smith Chart later, which simplifies the calculation of Zi for. I've constructed a 144/440 Dual band Open Stub J-Pole Antenna. A balun is necessary because a J-pole antenna uses a balanced feed (the. I saw the plans for this on the internet (link to plans) by Allen Lowe (N0IMW). 5 Meters of ribbon feed cable for a J Pole and 7. A while back, I build a 2 meter J-pole for indoors to use while scanning Rail Road frequencies. My SWR reading was 1. The DBJ-2: A Portable VHF-UHF Roll-up J-pole Antenna By: Edison Fong WB6IQN email: [email protected] Last week, in part 1 of the project, several variations of the J-Pole antenna were on display and discussed. The club also gives away one paid one-year ARRL membership (new or renewal) at each meeting. I needed to add elements and his first calculator had that, but didn't show dipole length and his new one didn't allow for adding elements. Less commonly available from CATV companies is the 3/4-inch 75-Ω. >The Slim Jim / J-Pole is essentially just a halfwave, endfed via a >quarterwave stub (in HF terms, a "Zepp" antenna). 89 - Indoor Loop Antenna for 80m. All you need to do is enter the desired resonant (center) frequency in the form below, then click "Calculate". The antenna has an omnidirectional pattern with a low take-off angle. Slim Jim antenna calculator & Slim Jim information. You can't squeeze more than the physics will allow out of half a wavelength. Cost about $6 using new parts. To find 1/4 wave in feet divide 234 by the frequency in MHz. The J-Pole antenna is a 1/2 wave antenna with a 1/4 wave matching stub. Yes, if your ladder line is 6″ wide it should be kept 12-18″ away from metal tower or pole. The short tuning stub was 49. This page documents a build of a 2-element 1/2 wave collinear J-Pole performed by Harry, KC9EOT, and myself, KB8OJH. The J-pole and the Slim Jim achieve similar performance. I own an arrow antenna for 2 Meters & 70 cm was wanting to build one for other bands but looking at the Space between the element and the matching stub a regular J-pole calculator has them closer together?. I started around 5am and modified Chang Puak's Yagi-Uda calculator to suit my needs. 2 on ch 1,1. The original idea came from the Arrow Antenna open stub J-Pole which is made and sold by Allen Lowe (NoIMW) for $39. 188" solid 6061-T6 angle. This calculator can be used to design a Slim Jim or a J Pole antenna. Yup, learning this was part of our journey, and we changed antennas 3 times along the way. When you open the calculator there are the following notes on the matching: For omni position the original scanner directions give a series capacitor of 250pf and a 9 turn inductor. V-U Antenna J-pole bibanda - Benvenuti su OfficinaHF! I've constructed a 144/440 Dual band Open Stub J-Pole Antenna. the SIMPLE 2m/440 Copper pipe "J" by Dale “Kuby” Kubichek, N6JSX 03/2001&2008 Can you use a pipe cutter or a hack saw, can you solder – then here is how to build a SIMPLE ”J” antenna that will more than double your 2 meter (and even 440) performance! The "J" antenna goes back many years, long before I became a ham. Vertical open stub antenna 40/20 meter: VHF End-Fed Half-Wave J-Pole: VSWR to return loss conversion: Quad 2 element 3 band 10 15 20mt: Quad 2 elementi per 144 Mhz: Quad Swiss Portabel,DH1PLY: Quad 4 elementi per 144 Mhz: Test measure balun, and compare antenna baluns or balums, W8JI: What is Numerical Electromagnetics Code: wire yagi 3 element. Open Stub J-Poles Photos of the OSJ 146/440. J Pole (1/2 wave vertical antenna) diagram. 88 KB; Synthesized Pulse Generator. The original idea came from the Arrow Antenna open stub J-Pole which is made and sold by Allen Lowe (NoIMW) for $39. J-Pole antennas get their name simply enough because they are in the shape of a J. That is a good thing. 1) An end-fed unbalanced half-wave to: 2) balanced quarter-wave stub to: 3) unbalanced feedline. It approximates the series inductance as a high impedance transmission line while the shunt capacitance effect is simulated by an open-circuited stub using Richard’s transformation. It is solving for Xc, not impedance. Since I had a Metal Fabrication background, I th… See more. The J-Pole antenna is a 1/2 wavelength vertical antenna with a 1/4 wavelength stub and is a popular solution for low power FM stations. We fabricated two identical J-Poles using the dimensions in this document, and both of them performed quite well, with a resonant frequency toward the lower end of the 2-meter Amateur band and a VSWR of 1. L-Tuner Simulator is a small, handy tool designed to help you calculate the input impedance of the L matching network, the impedance of the load (cables + antenna), or to find the Antenna impedance giving the cable length. Building VHF and UHF J-Pole Antennas. Open stub J-pole from Arrow antenna was originally a 2meter/70cm antenna and cut slightly to match the specs of the 152/462 antenna they also sell--- Have no need for now since Need a 2/70 antenna. Cubical quad X frame with antenna wire and terminal block added. 146 MHz marker. We already published in the 9 J-pole-antenna-projects some samples of copper J-Pole antennas. Note that the stub is only an open-circuit at UHF, acting as a small inductance in-stead, at VHF. Sounds complicated, but it really isn't. What can I do? A: Try adding a balun to the coax. Calculate input impedance with this application. The principle of a J Pole is well understood, and basically involves feeding the upper part of the antenna (a half wave dipole) with the lower part of the antenna (a quarter wave matching stub). 0dB/100feet at 146MHz and 2. PDF File here. The Wavelength is 11. Lots of considerations - first (and most important) chances are very good your roof system is not designed to support the weight of drywall. Looks like a “J”…(well, a backwards ^J in this illustration) … Make it out of wire and hide it in a tree Check reference section for websites that include a “J” pole calculator for Cu tubing like what was built as shown in the next slide. then instructs to do the calculation on the linked site (which was a handy little tool). Measurements and simulation confirm the quarter-wave stub modifies the circular H-plane pattern shape increasing the gain slightly on the side of the J Read Article. As with all folded dipoles, the currents in each leg are in phase, whereas in the matching stub they in phase opposition, so little or no radiation occurs from the matching section. 54 KB; Texas Instruments TTL Databook - 1976.