A multi-band wire antenna that performs exceptionally well even though it confounds antenna modeling software. Taylor, W2OZH, in which he described a low profile collinear coaxial array.
This antenna covers 80 to 6 meters with low feed point impedance and will work with most radios, with or without an antenna tuner. It is approximately feet long, can handle the legal limit, and is easy and inexpensive to build. The W5GI Mystery antenna, erected at various heights and configurations, is currently being used by thousands of amateurs throughout the world. Feedback from users indicates that the antenna has met or exceeded all performance criteria.
The antenna is especially well suited to hams who are unable to erect towers and rotating arrays. All that's needed is two vertical supports trees work well about feet apart to permit installation of wire antennas at about 25 feet above ground.
The W5GI Multi-band Mystery Antenna is a fundamentally a collinear antenna comprising three half waves in-phase on 20 meters with a half-wave 20 meter line transformer.
It may sound and look like a G5RV but it is a substantially different antenna on 20 meters. Varney had two specific reasons for selecting a 3 half waves on In short, the Mystery antenna is a sky wire that incorporates the advantages of a 3 element collinear and the G5RV antenna.
In its standard configuration, a collinear antenna uses phase reversing stubs added at the ends of a center fed dipole. These stubs put the instantaneous RF current in the end elements in phase with that in the center element. You can make these phase reversing stubs from open wire line or coaxial cable. Normally, a shorted quarter-wave stub is used, but an open-ended half wave stub would also work.
The problem is that the dangling stubs are unwieldy and or unsightly. An article written by James E. According to Taylor, when you apply a RF voltage to the center conductor at the open end, the stub causes a voltage phase lag of degrees at the adjacent coax shield.
This happens because the RF is delayed by one quarter-cycle as it passes from left to right, inside the coax to the shorted opposite end. Add up the delays and you get a total time delay of one-half cycle, or degrees.Great, great choice of antenna.
I have one question, build an antenna for cb 27Mhz vertical dipole. I must fix antena to this tube inch. Greetings from Serbia. Post a Comment. Wire Antennas for Ham Radio. Half-Lamda Tee Antenna. Twin-Led Marconi Antenna. Swallow-Tail Antenna. Random Length Radiator Wire Antenna. Windom Antenna - Feed with coax cable. Quarter Wavelength Vertical Antenna. Folded Marconi Tee Antenna.
Dipole Antenna - Balun. Multiband Dipole Antenna. Inverted-Vee Antenna. Sloping Dipole Antenna. Delta Fed Dipole Antenna. Bow-Tie Dipole Antenna. Multiband Tuned Doublet Antenna.
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Tilted Folded Dipole Antenna. Right Angle Marconi Antenna. Linearly Loaded Tee Antenna. Reduced Size Dipole Antenna. Doublet Dipole Antenna. Half Delta Loop Antenna. Collinear Franklin Antenna. Four Element Broadside Antenna. The Lazy-H Array Antenna. Sterba Curtain Array Antenna.
Vertical Collinear (20m)
Multi-Band Portable Antenna.This antenna covers 80 to 6 meters with low feed point impedance and will work with most radios, with or without an antenna tuner.
It is approximately feet long, can handle the legal limit, and is easy and inexpensive to build.
It is similar to a G5RV but a much better performer especially on 20 meters. Antennas for HF mobile operation The following description should give you guidance on how to build a mobile antenna for HF bands yourself, using a very cheap CB-mobile whip antenna base. Antennas for mobile operation 7Mhz ,10Mhz, 14Mhz, 18Mhz, 21Mhz, 24Mhz,Mhz 40 thru 10 Meter Zepp Antenna A modified 20 meter double zepp wire Operating Bands: 40 thru 10 meters with tunerbasic construction and performance information.
Antenna for deed restricted lots An effective m DX antenna for deed restricted lots, original article by K7ZB Portable Loop Antenna This loop it is small and light enough to carry while operating, it disassembles into small but rugged pieces that fit easily in a backpack or gym bag, and it can be tuned from 14 MHz to 30 MHz.Manifesting an ex reddit
This tunable magnetic loop antenna is my contribution to the well established art of amateur loop making. Can be tuned from 14 MHz to 30 MHz. You must only correct the lengths of the elements for QSY, see table down. For the bands 10 m and 12 m the Yagi is working as a reflector-radiator-Yagi, for 15 m and 17 m as a beam with radiator and director. This was created as a fun project to demonstrate how to enjoy operating HF in the field with a home-made portable antenna without spending a ton of money.
It fits on most balconies and must be hung from the ceiling. Performance considerations, detailed pictures and construction notes. This web page contains pictures, performance data, and enough construction details so you can homebrew your own.
Made with lightweight wooden "X" frame with two folded and linear loaded wire elements.
The two elements are approximately a half-wave each. Ham Radio operators review new sites every day sincefor potential inclusion in the Directory, and to evaluate the best place to list them. Operating Modes Operating Aids.
CB Radio Antique Radio. Home : Antennas : 20M. Yagi Antenna Plans. Search only in "20M Antenna Plans".French horn replacement parts
Add a new link. The DXZone is the largest human created and maintained library of web sites dedicated to Amateur Radio, currently lists Add our Daily Top 10 links gadgets to your site.I currently use only wire antennas which work fine on 40 and 80 meters, but on the higher Bands, I need some gain. My main goal is to be able to improve my ability to reach Stations in the Northwestern US and Canada. Since this is a bi-directional antenna, it will also help with my DX contacts.
This is a classic antenna design that has been used by many people. I am not claiming to be doing anything unique here. I am just keeping some notes to track my attempts to make this antenna work at my QTH. The picture of the antenna above is a little hard to see. It consists of 4 half-wave elements in a line, with two quarter-wave stubs between the pairs of elements.
Each stub is a piece of ladder line, with the end shorted. This provides the necessary phase shifting to align the half-wave sections to provide gain. The antenna is fed at the center and the feedpoint impedence is near ohms. In case anyone is interested in experimenting with the EZNEC model, here is the listing of the wires for this antenna. Note — this is just one trial set of element lengths. It may not be ideal for any particular location, and may not even be the actual dimensions I use in the final antenna.
AntennasHam Radio. You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account. You are commenting using your Facebook account.
Notify me of new comments via email. Notify me of new posts via email.Orfanidis - Lots Of Math! Also shows basic station interconnections - From Hamuniverse. This document has been recently upgraded to take advantage of the CSS system and have also added a button to allow the note to be downloaded as a PDF. Harold H. Dipole Height -- How High?? With a tuner covers the amateur radio HF bands from 40 - 10 Meters. The SWR is usually acceptable on the 3rd harmonic, although that is partly due to the increased feeder losses on But SWR is not the whole story.
This is usually not so severe to make the antenna unusable, and may be considered a reasonable compromise for the dual band coverage. If you do the simple math you will see that on you will have almost a 2 wavelength antenna, which is becoming what we call a "long wire" on the HF bands. As you probably know, a long wire radiates with multiple lobes, the largest of which are toward the ends of the wire.
In other words, most of your signal will be radiated up toward the sky. The reason for the coil in commercial dual band antennas is to phase the antenna currents so you actually end up with two colinear elements which both radiate at low angles, reinforcing each other and providing gain. Without the phasing coil you get multiple undesirable lobes. It is simple and works OK. This antenna can be built from low cost materials available from the local hardware store. Old TV Antenna Scheme.
Submitted by Gary Ruehle. My son and I built a dual 6 element stacked yagi for 2 mtr a couple of years ago. TV antennas were all the building materials we used.
After the antenna was complete, we could hit 2 different repeaters about 60 mi away using a 1 watt handheld. This antenna is highly directional. Amazingly strong for it's size, very abrasion resistant and you have to go looking for it if you're more than twenty feet away from the stuff. The coax connector is at one end of the dipole, where it is most needed. FMx - New To Repeaters? Orr Buy the Book Today! Beam Antenna Handbook by William I. Orr, Stuart D. Cowan Contributor Buy the Book Today!
Practical Antenna Handbook by Joseph J. Carr Buy the Book Today!The motivation for such a design is the fact that I have tall trees for a support and can actually pull such an antenna up into the trees to ft.
We all know that higher is better — and that is true with vertical antennas as well as horizontal dipoles.
The collinear design is simply two in-phase half-wave dipoles place end to end with a separation between the ends. This is simple enough in principle, but somehow you must feed each of the two half-wave structures with the proper phase while not having your feed lines short out the fields you are trying to produce. My first attempts fed the lower dipole via a co-ax line and I then tried to build a resonant structure that would send the wave up the wire to the top part of the antenna, phased with an inductor or a zig-zag delay line phase structure between the two halves.
Unfortunately, these designs were difficult to model convincingly. The biggest problem is with the inductor, which is doing double duty as defining the ends of the radiating half-wave sections and as the phasing element. There still may be hope for these all-wire designs, but for now it was time to move on to something more theoretically tractable.
I decided to try for a design that deliberately fed the upper section with a coaxial feed line. The design I ended up with is elegant, robust to small dimensional changes, and offers very good theoretical performance.Fe2 map test id list
The figure below illustrates the design process click to enlarge. The collinear antenna gets its increased gain by doubling the number of half-wave active elements, effectively increasing the antenna aperture. For this to work, the two elements must work together in phase. Transmission lines have the property that the currents are balanced along the line. A coaxial line illustrate this best.
20M Antenna Plans
The current coming out of the center conductor is balanced by an equal and opposite current traveling on the inside of the outer conductor. All of the fields, both electric and magnetic, are confined in the dielectric between the center conductor and the outer conductor of the cable. This happens because the mutual inductance of the two conductors of the transmission line is large and because, for RF frequencies, the skin effect prevents the fields from leaking out of the shielding conductor.
If you look at the inset in the diagram above, you can see how the balance currents in the feed transmission line must be identical as the currents injected into the transmission line to the top section, and also identical to the current magnitude on the lower half-wave dipole.
The practical implementation, c above, uses the outside of the coax shield as the dipole half-wave elements. The feed current, coming up the coax from the source encounters the break in the coax shield at the feed point for the lower dipole. For the currents to be continuous at this juncture, the current on the inside of the coax shield must turn the corner and go back down the outside of the shield.
We do this with resonant LC traps; the simplest version is just a coil of the coax itself to form the inductor L which resonates with the self capacitance C of the coil structure. At this point we have to compute the actual lengths of the elements and cable sections.Coronavirus, con la pandemia tornano popolari i drive-in
Keep in mind that the electrical length of the coaxial cable will be different inside and outside. For the transmission line properties we need to use the velocity factor of the cable to determine the correct electrical length, while for the radiating elements the wave velocity will be close to the speed of light, modified a few percent by any dielectric jacket on the coax. The table below lists the parameters that we come up with using this conceptual starting point in the 1st Cut column.
There are a number of competing constraints that we have to deal with. The length of the coaxial feed section is barely long enough to include the wound trap coils and the radiating sections of the dipoles for there to be any coax for separation between the top and bottom sections.
The free-space collinear antenna will get maximum gain when there is about 0. One method of addressing the matching problem would be to use an odd quarter wave length section of transmission line and transform the impedance from the top section to how it would appear at the bottom feed point. With the quarter-wave sections the wave-guide is ana-reflective and gets a perfect match when the impedance of the line is the geometric mean of the terminating impedances.
That might be possible by feeding the top section off-center. This is where optimization comes in. There are many variables, several paths to improved performance, but no definitive way forward.
The results of the optimization process significantly lengthen the connecting coax section and generate an off-center feed for the upper section as suggested above. This is all looking good. The 4NEC2 model is here if you wish to play with it yourself. The model included the effects of the insulating jacket on the coax and the THHN top section, so I hope the numbers are close enough to have good results on the first build. Practically, it will be good to understand the sensitivity of the design to the exact lengths of the various sections and how one could finally tune the antenna once it is ready to be deployed.Three towers support two 2-bay wide 4-bay high 5 band curtains at Radio New Zealand International.
From all indications this will be the highest gain array ever installed and used exclusively for amateur radio service on 80 and 40 meters. Read how the curtain evolves in the article below.
In order to understand gain, we have to understand the signal from a good basic antenna like the dipole. A dipole is the normal reference for comparing antennas. The dipole is also a basic building block of many antennas. Let's dispel a common gain misconception about dipoles and isotropic radiators.
A dipole does NOT have 2. Always remember that when you see antenna models over earth that tell you an antenna's gain in dBi. If a model over earth shows a "gain" of about 8. We cannot add 2. The instant the earth is involved in a model or measurement the 2. The plots below are for a foot high copper wire dipole modeled with high-accuracy ground over medium real earth on EZNEC:. You can see the gain is 8. Properly constructed curtain arrays or curtain antennas are a form of broadside radiators.
Their name derives from the similarity to a wire "curtain", or a wide flat sheet hanging vertically. The curtain's flat wide form occurs because broadside radiators generally use elements aligned in a flat plane at right angles to maximum radiation. Properly designed curtains require a minimum number of elements to obtain optimum gain for a given physical area.Dipole and Inverted V Antenna Basics
Other antennas may be less complicated to build, but a properly designed curtain has the highest gain for a given volume of space of any large array. Rhombics are no match for curtains, and neither are Yagis, unless perhaps the curtain is a curtain of made of small Yagis! Curtains can assume several common forms. These forms include vertically polarized arrays like the Bobtail, Bruce arrays, and H arrays.
They also more commonly include horizontally polarized arrays like bedspring arrays, Sterba curtains, lazy-H antenna arrays, or distributed feed curtains like the USIA arrays or HRS arrays used for shortwave broadcast. While E J Sterba E.
Sterba"Theoretical and practical aspects of directional. IRE, vol. The Lazy H is probably the most elementary form of curtain antennas. The lazy-H usually consists of two horizontally polarized doublet or dipole elements, although with some loss in earth reflection gain it can be oriented vertically as an "H". Each lazy-H element has in-phase currents. The lazy H always has broadside gain from parallel in-phase elements.
There are several publications and Internet pages showing incorrect or substandard feed methods. This is the common transposed feed line arrangement. This substandard feed method is highly dependent on feed-system electrical length, needlessly sacrificing gain, and restricting bandwidth!
At least one article containing this drawing claims the elements are being fed out-of-phase. It further states the array will work multiple bands with the feed system shown on the left.
The reasoning behind that statement is understandable. After all, the feed line is transposed.
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