The following program will calculate the lengths needed to construct several popular wire antennas. All you need to do is enter the desired resonant center frequency in the form below, then click "Calculate".
The correct lengths for the various models will be displayed in the chart.
To better understand the variables be sure to read the application notes and study the drawings, following. This calculator will accurately compute values for all HF antennas — 1. The basic formula for determining the length of a center fed, half-wave wire Dipole or Inverted Vee antenna is:.
This formula takes into consideration the capacitive "end-effect" from insulators which shortens the physical length requirement for the equivalent electrical length.
More importantly, for symmetrical current distribution, reduced feedline radiation, and thus a cleaner pattern, a balun should always be used at the feedpoint. The advice regarding the use a feedpoint balun pertains to the Inverted Vee as well.
This configuration, known as a "Doublet", will work well as a multiband antenna. Flat-Top Dipole or Inverted Vee? As is often the case when given a choice, there are trade-offs involved. The Inverted-Vee requires only one tall support, and less horizontal spread than the Flat-Top Dipole.
On the other hand there is some loss of gain because the pattern is less directional, and the bandwidth is narrower than the the horizontal dipole. You may purchase commercially made end insulators and center insulators with coax connectors built in, but why not make it truly homebrew and make your own hardware? It is quite easy using schedule 40 PVC pipe. Admittedly, if you are going to use a balun at the feedpoint, purchasing a center insulator with the balun built in is certainly a lot less work!
If you decide to roll your own, be sure all connections are secure, both mechanically and electrically. Be sure to properly solder all joints and to use weatherproofing. Remember to provide some type of strain relief at the center insulator for your "dangling" feedline. Not only does the feedline represent a strong downward tug, but when the wind blows the mechanical stress on your connections increases dramatically.
A good strain relief system is to wrap the feed cable once around the center insulator and secure it with "UV-Resistant" usually black tie-wraps. You will, of course "invent" something much more sophisticated for your design!
Believe it or not, even zip cord lamp cord will perform quite well. Of course you need to "size" your feedline according to the power you intend to run. Power in excess of watts can develop very high RF voltages. Be sure your feedlines and antenna hardware can handle the power.
Wire Antenna Calculator
In the real world — where you build your antennas — the actual impedance of your wire antennas will depend on several variables. Always cut your antenna lengths a bit long. This will allow you to "fine tune" the antenna by trimming. You will quickly learn that "trimming" is a LOT easier than "adding to"! When you decide where to "hang" your antenna, remember that the horizontal radiation pattern of a Dipole in free space is a wide "Figure-8", which radiates perpendicular to the axis of the dipole.
The vertical radiation pattern depends on the height above ground. As stated above, to be an effective DX antenna, a low-angle signal take-off is required, and that means your dipole must be at least one-half wavelength above ground.
If you choose to build an Inverted Vee, be sure the angle of the sloping legs is not more than 45 degrees the inside angle at the feedpoint is not less than 90 degrees.I am a math geek, computer nerd, and recovering civil servant. I have come up with a trio of web-based calculators which should help you design and build your own wire antennas - no need to buy expensive kits when the wire you need is available at the local hardware store for a fraction of the price! I will post the download link here soon.
Thanks to Janis for allowing me to use her soapbox for a bit. I hope you find my calculators useful. Just put in the frequency you want the antenna to be resonant on, choose the type of antenna you're making from the drop-down list, and whether you want to use insulated or bare wire.
Then click [Calculate] and Bob's your uncle. I would suggest adding a little bit to the length you get, as real life is never as neat as mathematics. And shortening is much easier than lengthening. It allows you to test the resonant frequency of the antenna for lowest SWR and zero reactance, and adjust the length to the exact frequency you want, in just one step, rather than a lengthy process of cut and try.
The only problem is, what to do if you don't know the current length of your wire antenna? Instead of taking it down just to measure it, you can use the Wire Antenna Length Calculator above to estimate it. Since we're probably talking about very short lengths relative to the full antenna, this should be close enough. The tricky part is that it needs to know your coax's Velocity Factor.
If you know it, or have the original spool the coax came on, you should be fine. If not, I found a couple of places see below to look up the VF based on the coax type. If the markings have rubbed off your coax, I even found a calculator to let you get the VF of a piece of coax using an antenna analyzer. Thanks, W6LSN!
This calculator is also simple enough.Here is a simple antenna calculator for two popular forms of ham radio HF wire antennas: the horizontal dipole and the inverted "V". Enter your desired frequency MHz of operation i.Ten Must-Have Items For Portable Amateur Radio.
If you have no particular preference within a given ham radio band, then simply enter its center frequency i. To fully understand the results obtained by this calculator, please take a few minutes to read the explanation below it. Be prepared to trim the ends of the inverted V dipole if the final frequency of resonance ends up being too low for your needs when the inverted V is installed in its permanent position.
The antenna calculator above uses this formula as a starting point to calculate wire lengths for the dipole. The results are conveniently displayed in inches, centimeters, feet and meters. This formula to obtain the length of a half-wave dipole antenna will give a good ballpark value to start with. However, the actual resulting frequency of resonance and feed-point impedance of a dipole will depend on:.
When each side of a dipole slopes down from the feed point, it is commonly called an inverted V. But if one were to actually do that, the inverted V would resonate at an even higher frequency! This will give you some leeway to trim the wire ends back if the inverted V resonates too low for your purpose when installed in its final position.
The formula used by the calculator to compute the wire lengths for the inverted V is based on the formula for a half-wave dipole. It is adjusted to take into account the special characteristics of the inverted V. In the case of the inverted V we must add - to the list of environmental variables influencing the half-wave dipole - the angle between the two legs of the inverted V.
The angle below the two sections of a horizontal dipole is degrees. As the two sections of the dipole are lowered below the feed point, the angle between the two legs decreases:. To avoid the latter outcome, the antenna calculator above is set up to compensate somewhat for local adverse environmental conditions.
The length it will calculate will likely be a little too long. You will only have to trim it a few inches at a time to bring the frequency of resonance up to where you want it.
For more detailed information on ham radio HF wire antennas, please visit this section of our Web site. If the angle between the two legs of the inverted V becomes less than 90 degrees, the radiation patterns from each leg of the inverted V begin to interact and cancel each other to some extent.
Therefore, the angle between the two legs of an inverted V should not be less than 90 degrees. Remember, an inverted V requires slightly more wire than a horizontal dipole for a given frequency of resonance. The antenna calculator above will provide appropriate wire lengths for the inverted V and the dipole for a given frequency of your choice. HF Antenna basics are not hard to grasp when explained in simple terms as they are in these e-books.
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Thank you! Click here to read all about it It's kind of special!About Wire Antenna Calculator The resource is currently listed in dxzone.
The main category is Antenna design calculators that is about Antenna design calculators. This link is listed in our web site directory since Thursday Nov 16and till today " Wire Antenna Calculator " has been followed for a total of times.
So far received 14 votes for a total score of 7. The scale is 1 - 10, with 1 being poor and 10 being excellent. Webmaster, add a Remote rating Related links We thought you might also be interested in these additional resources we selected from the same category: Quad calculator - Cubical quad antenna calculator in java script let you calculate eleme Amateur Vertical Antenna Calculator - This basic calculator is designed to give the aproximate length heigh Log Periodic Antenna Design - calculates the dimensions and spacings of the elements needed to build A simple jscript calculator Visit this link Wire Antenna Calculator Visit Site Share this resource Share this link with your friends, publish within popular social networks or send it via email.
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Service provided by Google FeedBurner. Visit Site.H ave you been thinking about experimenting with a loop antenna, but are not sure you have enough space to put one up? Have you heard that loops come in many "shapes and sizes" and are confused about what might work best for you at your particular location? Would you like to see "at a glance" if you have room for a loop? It also calculates measurements for: A square or diamond loop shape A rectangular shape with a ratio, where the horizontal is longer than the vertical length by a factor of 2 A delta or triangular loop shape A circular shape in the HF and VHF Amateur Radio bands.
NOTE: All results may be presented in either feetmetersor centimeters. See Hints and Tips below for suggestions about actual construction techniques T he purpose of the calculator is to give you a quick overview of the feasibility of "squeezing" a loop into your available yard or apartment space.
It does not calculate inductance, impedance, or even "Q" factor values since it is assumed that tuning will be accomplished using open feeds and a transmatching device, which should more than adequately compensate for the range of construction and materials variations as measured by these parameters. T hese calculations should be able to tell you at a glance if you have room for a loop!
I hope so NOTE: You may deduct Don't forget to include an additional height above ground for the lowest horizontal element when determining the total vertical dimension, usually six or seven feet for safety reasons, i. To see how the calculator works, click on the " Random Sample " Button. Or, enter a value in the Frequency megaHertz text box, the Band text box, the Wire Length text box, or select an entry from the drop down menu, and then click on " Calculate Dimensions " to see the values you are interested in Repeatedly pressing the " Mid-Band " button displays the wire lengths, and design dimensions, for the center frequency in each of the amateur bands in turn.
A single press for any given frequency, occurring within a valid amateur band, will also show its mid-frequency point for that band range. Pressing the " Mid-Band " button after entering a wire length, will identify the lowest frequency loop, or largest antenna size, within an amateur band. A subsequent press will calculate the actual mid-band dimensions for that band as usual.
NOTE : Wire lengths for a mid-band frequency may prove to be the most practical since you may tune above or below to obtain full coverage over the entire band! The probable exception here would be the m band. Tuning down from the mid-point might place a tuner box under considerable electrical "strain" and would not be recommended. So, you can't "cheat" at m, you will most likely need the full loop for its lower band edge frequency.
For a broader discussion of antennas used in packet radio, please see Packet Radio Antennas. A Few Operating Notes : The conversion factor, as applied in feet-to-meters calculations, is: 0. Thanks to Steve, G0SGB for keeping me honest : Geometry buffs might notice an equivalency between the side of a square and the height of the square's diagonal when sloped at 45 degrees.
This implies that a vertical square loop has the same height as a 45 degree sloping diamond square loop. Interesting : For radio buffs, this means that you only need one support if you use the sloping diamond shape. Are these two antennas comparable in performance? A good research question! The sloper certainly has a larger "footprint" and possibly a significantly different radiation pattern. T here are several factors to consider when choosing your wire gauge and type.
As you know there is solid, stranded, covered or insulated, and bare. A general principle is: as you move up in frequency, wire size and type matter! As you move down in frequency, these parameters become much less critical, or even relevant! For example, for an 80m loop, the diameter of the wire compared to its length is going to be a very small ratio. And, it is this ratio that plays a key role in determining the inductance of the antenna. So even if you double or half the size of the wire, the outcome is not going to be significant enough to be concerned about at these very long lengths of wire However, for a loop approaching the microwave region, wire size and type become central to the design of the antenna!
The formula noted above, for the length of the loop, is probably not going to be very accurate in this regard.This is ostensibly true, but to access results older than 30 days requires clicking through a calendar, day by day, and entering CAPTCHA codes for each one. Before long you find yourself in an infinite CAPTCHA loop, unable to continue, blocked from any attempts to tabulate the hard evidence. Two real-world bettors, one of whom is a former financial analyst in his late 20s who is highly regarded by oddsmakers, developed a script to scrape Pregame.
You can view and download a spreadsheet containing all the data, including every single Pregame pick dating back to Jan. It is a large file and may take several minutes to open. Based on full record of Pregame picks. The data covers 49 touts who sold their plays during this period (not including those whose existences have been completely expunged from the archives, like David Glisan, Mike Hook, and Stan Sharp), and of those 49, only 11 of them showed a profit.
Of those gains, most were marginal and would be wiped out by standard fees. Flipping a coin would have been a more cost-effective strategy. Based on full record of Pregame picks plus standard per-pick prices. His touts, he claims, win 55 percent of the time. Such a strike rate would be a license to print money. Bell is smart enough to understand that shouting about winning records of 75-90 percent, as some barrel-bottom touts do, would only garner ridicule. It tells you something that for all their supposed professionalism, touts still use aliases.
At Pregame, the big ones go by names like Fezzik, Goodfella, Spartan, Sleepyj, VegasButcher, and King Creole. In July 2014, Bell patted himself on the back when he announced on Pregame a new standard for his touts: They had to publicly provide their real name and a signed declaration declaring any past legal troubles.
Dipole Antenna Calculator
As touts bounce from site to site, sometimes under different names, there really is no way to determine their true track records. Touts plug away despite columns of red, all the while advertising useless cherry-picked short-term streaks or outright falsified ones.
Like most touts, Coach sold picks in a few places. Every Super Bowl, places like The PBS NewsHour turn to the bespectacled Covers as the prototypical long-time professional bettora sharp. Teddy Covers is as sharp as a marble.
A documented six-year loser at SportsMemo, he became one of the faces of Pregame after joining in August 2014. How rare was it. He had sold another one nine days earlier.One suspects that Cunningham would have approved. And the company is dancing especially well these daysduring its winter season (at the David H.
The national company was founded long before the revolution, by the Cuban-born star Alicia Alonso, and remains a prized institution, as beloved as baseball. Modern dance has had a harder time putting down roots there, but lately that has started to change. Malpaso Dance Company, founded in 2012, is part of this new flowering.
Amateur Vertical Antenna Calculator
The independently run company, stocked with vibrant, beautifully trained dancers, tours abroad extensively and, thanks in part to the Joyce Theatre Foundation, regularly commissions work from outside choreographers. Thank you to our students for making Summer 2017 a great success. Please check back on December 15 to learn what is in store for Summer 2018.
This summer, spend an exciting week becoming familiar with college life, exploring fascinating subjects and making new friends. Our one-week non-credit Summer Preview program offers a choice of seminars to rising high school freshmen and sophomores.
Take advantage of this opportunity to explore an area of academic interest or become familiar with an entirely new subject. Browse Seminar ChoicesView the Full CalendarOur Summer Preview seminars offer academic, residential, and social opportunities through small-group lectures focused on a specific topic and planned activities. Alongside other motivated peers, you gain exposure to an area of academic interest, experience college life at Boston University, and start friendships with students from around the world.
You also benefit from a college workshop designed to help you maximize your high school studies so you are prepared to fill out college applications when the time comes. We also offer a variety of planned social group activities so you can get to know Boston University as well as the city of Boston.
Summer Preview is open to both commuter and residential students. Please note that you must be 14 years of age or older to live in the dorm. Learn More and Apply Get the scoop on seminar topics, program activities, and favorite moments of the Summer Preview program from last summer's students.
Learn More and Apply The Big Picture Get the scoop on seminar topics, program activities, and favorite moments of the Summer Preview program from last summer's students.
Brady, Anne B BrittPlant Physiol. Gommers, Elena MontePlant Physiol. Townsend, Renata Retkute, Kannan Chinnathambi, Jamie WP Randall, john foulkes, Elizabete Carmo-Silva, Erik H. Jinkerson, Sophie Clowez, Cawa Tran, Cory J. Krediet, Masayuki Onishi, Phillip A. Day, James Whelan, Renate ScheibePlant Physiol. Shimada, Makoto Hayashi, Ikuko Hara-NishimuraPlant Physiol.
Keurentjes, Maike Stam, Frank JohannesPlant Physiol. In many ways, it's a Super Bowl of the lower weight classes, featuring a rising star in Lomachenko (9-1, 7 KOs), who captured world titles in two weight divisions in just his seventh pro fight, and the enigmatic Rigondeaux (17-0, 11 KOs), among the greatest defensive geniuses in history.