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Topic: Dipole antenna

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In the News (Tue 23 Jul 19)

Antenna gain is comparable to panel antennas including the Freedom Antenna Set sold in Finland.
The one arm of the dipole is soldered both to the centre rod and to the half of the copper conduit.
The one arm of the dipole is soldered both to the centre rod (2) and to the half of the copper conduit (1).
www.saunalahti.fi /~elepal/antenna1.html   (1412 words)

 Two position fold-over dipole antenna - Patent 5561437
Antenna arm 441 is attached to surface 462 in recess 463 of rear flap housing section 111 using a suitable commercially available adhesive.
Thus in the closed position, antenna arm 440 and the antenna arm 441 are substantially parallel with one another, are aligned, such that the antennas overlap when the first housing portion 108 and the second housing portion are in the collapsed position.
The dipole antenna also performs well when the arm are not fully extended, but are positioned relative to one another at an angle of approximately 120-180 degrees.
www.freepatentsonline.com /5561437.html   (3905 words)

 FlashWebHost.com - ANTENNAS Construction Guide for Ham Radio Transmitters.
Antenna is the means by which a wireless operator puts his signal into the space and also through which he picks up the signals of the stations with which he wants to communicate.
The overall length of the dipole is half the wavelength of the frequency for it is used.
Since the beam antenna radiates all the energy only in the same direction to which it points, a rotator has to be used along with it, to rotate the antenna in all directions to make best use of its directional property.
www.flashwebhost.com /circuit/antennas_for_ham_transmitters.php   (1907 words)

 Current distribution of a VLF electric dipole antenna in the plasmasphere
One of the most important characteristics of such an antenna is the current distribution along the length of the dipole, since it is this current which ultimately determines the amount of VLF power which can be radiated from the antenna into the plasma.
In the present work we determine the dipole antenna current distribution from first principles, constructing an integral equation of the Hallén type relating the current distribution to the wave vector potential.
In the case of the dipole antenna oriented parallel to B
www.agu.org /pubs/crossref/2006/2005RS003260.shtml   (344 words)

 Welcome to the Folded Dipole Page
Having a folded dipole does not mean that you have an antenna that is folded in half and so you obtain an antenna that now takes up half the space of a regular dipole.
If the power to a regular dipole antenna was 100 watts and the current was 1.2 amps, we'd solve for R as R = 100 / (1.2*1.2), which is the same as R = 100 / 1.44, which is 69.44 ohms.
In the folded dipole the wires are in parallel, the current must be divided between the two wires.
www.qsl.net /w4sat/fdipole.htm   (696 words)

  Dipole antenna :: Radio-Electronics.Com
The length of a dipole is the main determining factor for the operating frequency of the dipole antenna.
Although the antenna may be an electrical half wavelength, or multiple of half wavelengths, it is not exactly the same length as the wavelength for a signal travelling in free space.
Typically it is between 0.96 and 0.98 and is mainly dependent upon the ratio of the length of the antenna to the thickness of the wire or tube used as the element.
www.radio-electronics.com /info/antennas/dipole/dipole.php   (893 words)

 Terminated Folded Dipole Antenna   (Site not responding. Last check: 2007-10-12)
Its not the best antenna in the world, but is better than no antenna, or one that is not operating properly; and requires virtually no maintenance allowing it to survive when essentially ignored by those who would require its services, which is mostly the case.
Antennas mounted at low elevations at low frequencies will also have associated losses, and the plots were done at various heights to display this.
Antenna tuners of many designs are lossy devices, and common practice in amateur radio is to place the antenna tuner at the operating position and feed the coax from the tuner to the antenna under high SWR.
www.co.missoula.mt.us /acs/antennas/t2fd.htm   (996 words)

 dipole antenna - a definition from Whatis.com
A dipole antenna is a straight electrical conductor measuring 1/2 wavelength from end to end and connected at the center to a radio-frequency (RF) feed line.
This antenna, also called a doublet, is one of the simplest types of antenna, and constitutes the main RF radiating and receiving element in various sophisticated types of antennas.
The polarization of the electromagnetic field (EM) radiated by a dipole transmitting antenna corresponds to the orientation of the element.
whatis.techtarget.com /definition/0,,sid9_gci214149,00.html   (319 words)

 Simple FM Dipole Antenna   (Site not responding. Last check: 2007-10-12)
A dipole is basically a length of conductor (wire) split into two portions and signal is taken off at the split.
The length of a half wave dipole in feet is calculated as 468 divided by the frequency in MHz or in inches as 5606/F mhz.
Therefore, a dipole for 98 MHz which is band center of the FM broadcast band, works out to 4.78 feet or 57.3 inches.
www.northcountryradio.com /Articles/fmdip.htm   (405 words)

 The Dipole Antenna
The antenna input of the radio and the antenna itself are two distinct circuits, and if they are close to each other in impedance, a maximized transfer of power will take place.
If you slope the antenna away from one support, such as your house, do it so that the side of the antenna connected to the inner conductor is the higher side.
As a general rule an antenna that is too long works better than one that is too short, so cut it for the lowest frequency (longest wavelength) band you have room for and you will be pleased with the performance.
dzabcik.home.texas.net /dipole.html   (856 words)

 The Buddipole™ - HFportable dipole antenna system
Our HF portable dipole antenna is instantly configurable as a vertical dipole or any one of several other shapes including a vee dipole, sloper, or L shape.
The Buddipole dipole antenna is directional and can be converted to a an effective single element vertical antenna (the “Buddistick”) by using either one of the dipole antenna arms and a counterpoise.
The Buddipole or Buddistick are perfect for space-restricted covenants such as use as an apartment antenna, hotel antenna or backup marine antenna, or as a compact dxpedition antenna or backpack antenna.
www.buddipole.com   (215 words)

 Tuner + Coax Line + Balun + Balanced Line + Dipole
The antenna is treated as a balanced-twin line open-circuit at its far end, with an electrical length equal to half of its actual dipole length, plus "end" effect, plus the effects of ground proximity.
Transformation of the antenna input impedance to 50 ohms is as accurate as the data input.
At heights exceeding 1/3 or 1/2 wavelengths only a very asymmetrical feedline relative to the antenna wire might have a noticeable effect on input impedance but none on radiating efficiency except that a distorted radiation pattern may be considered in some rare circumstances to be equivalent to a loss of power.
www.smeter.net /antennas/dipole3.php   (1648 words)

 Distributed Capacity Coaxial Dipole Antenna
Also, this dipole has a large circular area over its entire surface, thus a low Q. Over a 5 year period of testing, K7UAE, reports an arithmetic mean average of 1.5db gain over a simple dipole out to the same frequency and instlled at the same height and configuration.
Since this coaxial dipole is completely covered by a vinyl jacket, it greatly reduces static charge build-up which discharges causing a popping noise in the receiver.
Any signal fed to the antenna which is harmonically related to the antenna's operating range is reduced by considerable amount as compared to a simple dipole.
www.k9gd.com /DCCDA.html   (850 words)

 Ham-Shack.com : It's So High . . .
Because so very few people are able to get their antennas 240 feet in the air, most of them settle for 40 to 60 feet for their 80 meter dipoles.
The coax and antenna should form a right angle for as far as possible, so that it does not interfere with the radiation from the antenna.
Dipoles are rarely used on frequencies above the two meter band because beam antennas are small and easy to built for the UHF frequencies.
www.ham-shack.com /antenna_location.html   (1001 words)

 A cheap and easy TV antenna
This antenna is optimized for a single channel, though it will often work acceptably on others.
The antenna is made from "300 ohm twin-lead" the brown or fl ribbon-like TV line that we all used before the days of cable television.
For some additional improvement in reception, cut a similar piece of wire about 5% shorter than the antenna, and mount it parallel to the antenna on the side toward the station, about 0.15 wavelengths (in air) from the antenna.
www.wfu.edu /~matthews/misc/dipole.html   (640 words)

 Amateur Dipole Antenna Calculator
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.
The center of each Tee should be joined to the end of each of the dipole main elements.
To optimize the antenna for a frequency RANGE, do the calculations twice, once for the low end of the range and once for the high end; then average the two and plan to adjust the VSWR on both ends of the range as needed.
www.csgnetwork.com /antennaedcalc.html   (185 words)

 How to make a simple dipole for your AR8000   (Site not responding. Last check: 2007-10-12)
It describes the construction of a simple dipole antenna suitable for use with a handheld scanner such as the AOR AR8000, and describes some of the benefits of using such an antenna.
In it's first incarnation, the dipole was made up of two 44cm lengths of wire cut from a single coathanger; this was simply because I didn't know if it would work, and couldn't be bothered to cut up more than a single coathanger, and 88cm was the maximum length I could get out of one.
The antenna herein presented is very effective, very powerful (better for airband than either of the two commercial whips that I own) and very cheap, making it very attractive to people like myself who pursue their hobbies on a budget.
www.crypticide.com /users/alecm/radio/ar8k-dipole.html   (1304 words)

 The Hairpin Monopole Antenna
A folded dipole antenna is a center-fed half wave dipole with another half-wave element close to it and joined at the ends as shown in Figure 1.
Electrically, a dipole antenna can be expressed as a series resonant circuit consisting of a resistive component and two reactive components.
Thus, for the same amount of power fed to the antenna (or received by the antenna) only half the current appears at the feedpoint and the resistance is increased by 4.
www.antennex.com /preview/monopole.htm   (1359 words)

 The Double Bazooka Coaxial Dipole Antenna
The BAZOOKA antenna design was developed by the staff of M.I.T. in the early 1940's for use by the U.S. Government as a radar antenna.
This antenna can also be installed in an inverted V fashion "Center elevated, with 90 - 120 degrees between the legs" Then it will have vertical polarization and will usually out perform a dipole type antenna at distances of over 500 miles due to its lower angle of radiation.
The Bazooka antenna consists of a half- wavelength of coaxial line with the outer conductor opened at the center and the feedline connected to the open ends.
www.bloomington.in.us /~wh2t/bazooka.html   (1574 words)

 TV Antenna Introduction
Anything that conducts electricity is an antenna, (usually a wire, but it could be your body) but the basic unit from which we build antennas is a wire, 1/2 wave length long having a connection in the middle to equipment.
Called a dipole, it is an efficient radiator of alternating current electrical energy and is a standard of reference for other antennas.
Although some techniques can slightly extend antenna area beyond its physical size, and although a badly designed antenna can have a much smaller area than its physical size, capture area is pretty much proportional to the size you see.
www.kyes.com /antenna/dipole.html   (723 words)

 Atom Voyages | Making a Dipole Antenna
If you want to use the dipole on frequency bands other than the one it was cut for, you can connect the center pin of the dipole's coax connector to the tuner, leave the shield disconnected, and run it as you would a standard backstay antenna.
For an SSB receiver antenna you can use any of the antennas used for a transceiver, such as an insulated backstay, vertical whip or a random length wire hung near the masthead and tied off at the corner of the afterdeck or stern rail and then run under the deck to the radio.
If the above mentioned antennas are too elaborate for your needs, you can always connect a piece of insulated copper wire of any size and length to the center pin of a plug in your external antenna jack, connect the side of the pin to ground, and hoist the antenna wherever it's convenient.
www.atomvoyages.com /projects/dipole.htm   (2958 words)

 Broadband folded dipole antenna
This antenna was designed at Barker and Williamson by the request of the United States Government more than 20 years ago.
Always use the longest antenna that will fit your space, as it will have better radiation efficiency at the low frequencies and give you a stronger signal.
NVIS propagation is performed as a flat-top from ground level to approx 12 feet high, depending upon frequency, ground conditions and distance of coverage desired.
www.bwantennas.com /pro/fdipole.pro.htm   (667 words)

 [No title]
This antenna is a fairly easy to construct antenna and will give you better reception on the frequency it is cut for.
FREQUENCY-A dipole antenna will not only work well on the frequency it is cut for, but also for the multiples of that frequency.
A dipole will work well on frequencies that are an ODD multiple of 1/2 wavelength frequency the antenna is cut for.
www.angelfire.com /mb/amandx/dipole.html   (1098 words)

 Dipole/Yagi Antenna   (Site not responding. Last check: 2007-10-12)
To tune the antenna, each dipole must be trimmed separately by cutting small equal length pieces from each end until a low SWR (below 1.5 to 1) is achieved for the low end of the band.
If you trimmed the dipole SWR for the low end of the band as previously instructed, you may find the resonance is now in the middle of the band.
The antenna modeling was done with all the wires in the yard included in the model to get the whole story of how well this antenna should do for me. First on 20 meters...
home.teleport.com /~nb6z/yagi.htm   (1027 words)

 Ham-Shack.com : Setting Your Mind on Polarization
A dipole antenna, or an antenna that is parallel to the Earth's surface, will produce horizontally polarized radio waves.
Almost all amateurs use a vertical antenna of some kind of their mobiles, because placing a beam antenna on a vehicle is very impractical.
There are many different types of mobile antennas, ranging from those that mount on a car roof or trunk lid, to those that mount on a glass window.
www.ham-shack.com /polarization.html   (573 words)

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