It resembles a coaxial antenna whose lower section consists of straight elements called radials instead of a hollow conducting cylinder. An efficient vertical antenna, such as a medium wave broadcast tower might appear to work off the earth ground however it most likely has conductive radials buried just below the surface the number of them and the. The ground plane antenna consists of a vertical rod lifted by four radials. It contains many calculators to help you design radios and antennas for all your projects. Verticals are commonly installed at ground level, although you can also place a vertical on the roof of a building. The first antenna that you should consider building is the quarterwave groundplane antenna for the 2m band. Of particular interest was how much was actually to gained as the radial numbers were made larger and the point of vanishing returns. I have made a page showing some images and construction details. Maple leaf communications assumes no responsibility for material calculation errors or other deficiencies in the calculator offered here.
Amateur vertical antenna calculator this basic calculator is designed to give the aproximate length height of a particular vertical antenna, for the frequency and wavelength chosen. Actual antennas can vary between these two extremes. Amateur vertical antenna calculator this calculator requires the use of javascript enabled and capable browsers. This calculator is designed to give the vertical length of a quarterwave ground plane antenna, and the length of each of the four radials for the selected frequency you have entered. Verticals are commonly installed at ground level, although you can also place a vertical on the roof of a. Its just one end of my g5rv dipole, or sometimes called a dummy load.
Each radial is evenly spaced 90 degrees apart from each other around the vertical element. The horizontal radiation pattern is a circle where the antenna radiates equally well in all directions. Indeed, when a vertical antenna is erected at ground level and powered, there are much ground currents generated by the earth capacitance and resistance that increase the effect of the earth on the antenna losses associated to losses in the transmission lines, etc that see its radials running at ground level be completely detuned. Note, however, that, for best performance, the ground plane antenna should be isolated from the tower structure.
Instead of a solid ground plane, you could use four radial wires, 0. Is a ground plane necessary for transmitting and receiving. It is found that for a monopole antenna like a quarter wavelength vertical, the ground acts as a plane to reflect the radio waves so that an image of the top half of the antenna is seen in the earth. Quite often a vertical antenna or a random wire is one side of the antenna and the earth ground is the other a flat plane. Since the radials are elevated, the ground losses are minimized, even though there are only two of them. The idea is simple enough hang a wire vertical from a support, using two elevated but sloped radials to form a basic ground plane antenna. High performance 40 meters vertical without radials. The normal quarter wave ground plane antenna consists of a vertical radiator which is insulated and centered between 4 horizontal surrounding. The inverted vee antenna legs will be longer by 2 6% from those of the horizontal antenna depending on the angle. Listed under the antennas antenna calculators category that is about antenna design calculators. The simplest idea of a groundplane antenna is that you take a quarter wave vertical and add four quarterwave radials at the base. The vertical element and radials are 332 or 116inch brass welding rod. It follows the fm convention of vertical polarization.
Apr 08, 2012 the first antenna that you should consider building is the quarterwave ground plane antenna for the 2m band. If you have no particular preference within a given ham radio band, then simply enter its center frequency i. The normal quarter wave ground plane antenna consists of a vertical radiator which is insulated and centered between 4 horizontal surrounding radials which extend out from the base of the antenna. Find the lowest frequency for which you have minimum return loss. A closer look at vertical antennas with elevated ground. Antenna design calculators category is a curation of 83 web resources on, parallel square conductor transmission line calculator, analysis of antenna mast strength and bending stress, full wave loop antenna calculator. As shown in figure 3 a small secondary lobe grows at high angle. It is possible to simulate this function by replacing the real earth. The conductor width isnt of great importance in the design. You should use an rf choke balun in the transmission line to prevent rf from. A basic antenna like a dipole is selfcontained and requires no ground plane. Firestik lg3m2w 3foot firefly cb no ground plane antenna kit white. Choose from quarterwave, halfwave, the powerful 58wave, 34wave, or fullwave, and calculate minimum lengths of required radials, and then shop for your needs on our other pages and select from our inventory of aluminum, fiberglass, wire, coax, connectors, and other parts and. Hb9sl vp2e directional wire antenna dd5lp g8glm vk2ji blog.
A vertical antenna with radials bent down at approximately 45 degrees will have a natural impedance around 50 ohms making it a good match to the radio in use. The antenna is designed to be fed with 50 or 75 ohm coax cable of most any length with a balun. A ground plane antenna is a variant of the dipole antenna, designed for use with an unbalanced feed line such as coaxial cable. This is usually achieved with radials, either attached to the base of the vertical, or buried below a ground mounted antenna. This is, of course, the familiar groundplane antenna being viewed as an asymmetrical dipole. A quarterwavelength antenna is easy and inexpensive to build and can be an effective antenna with a low angle of radiation that is, power is radiated out, not up. Helical model and predict helically wound vertical antennas this program models and predicts the performance of a helically wound vertical antenna, mounted immediately above a ground plane, topcapacitanceloaded with a vertical rod or whip. In verticals, something below must provide ground to complete the rf wave. Helical antennas invented by john kraus give a circular polarized wave.
That image isnt an actual current or dipole at the position of the image antenna. The amountsize of the groundplane required for the optimal performance of a monopole antenna is determined by the frequency you are transmittingreceiving at. Amateur quarter wave ground plane antenna calculator. They are very easy to build and will perform better than the antennas that come with most handhelds. Testing lora antennas at 915mhz home wireless medium. I have been making a few 14 wave antennas lately, mainly for uhf and the ghz bands with good success, so i decided to create a calculator to simplify the process and maybe get some people who have not tried one before to give it a go. Find a tube with a circumference equal to one wavelength, and wrap wire in a helix spaced a quarter wavelength. Aug 07, 2007 in discussions of principal plane patterns or even antenna patterns, you will frequently encounter the terms azimuth plane pattern and elevation plane pattern. Maximumgain radial ground national contest journal. If you are just getting experience in building antennas or you are an old pro, here is a simple and fun project. Listed under the antennasantenna calculators category that is about antenna design calculators.
Blog antenna ground plane calculation arcadian antenna. A single band 14 wave ground plane vertical antenna can be installed atop a tower. Dipole, inverted v and ground plane antenna calculators. A groundplane antenna is a form of dipole antenna designed to work with an unbalanced feed line. This particular ground plane is constructed out of. Aug 21, 2018 to the rescue, would be an external antenna. Ease of fabrication and cost makes the groundplane antenna one of the popular antennas in communication systems. Courtesy of and designed by n2imf joseph r mielko this downloadable calculator will provide you with good starting measurements for a basic ground plane, inverted v or standard dipole antenna. This calculator was adapted from the coilshortened dipole antenna calculator. Dec 30, 2015 another little application written to help aid in vertical antenna construction. Ideally for radials you should have them sloped downward at a 45 degree angle to help provide a better match. With dipoles, one half of the antenna is your ground. As the name indicates the antenna ground plane acts as a simulated ground. Whats the difference between a dipole and a ground plane.
For angles greater then 90 degrees the legs will have less of an increase in length. Download software 14 wave antenna with ground plane. If you have been in the market for a vertical you have probably noticed the availability of a tuner required vertical which is fortythree feet in height above a reasonable ground plane of radials. The antenna is designed to be fed between its base and the ground plane operating at its 14wavelength. Maximumgain radial ground systems for vertical antennas al christman, k3lc table i optimum number and length of radials for a vertical antenna on 40 meters 7. A ground plane antenna project for 10 meters band by n4zaw. In an electrical sense, a vertical is a dipole with half of its length buried in the ground or mirrored in its counterpoise system. Enter the frequency in mhz and click calculate it will give you the length for the radiating element as well as the ground plane elements. Pay no attention to the wire goingoff horizontally from the base. A solid ground plane will work, and it should be a quarter wave radius. A ground plane antenna by definition gives you a ground plane, but still, if you antenna has a good ground plane there should be only marginal deferences.
Cb wilson firestik francis astatic cb radio antenna ground plane 38 x 24 black tip mirror trucker. Installed antennas can be affected by buildings, trees, mast properties, other antennas, ground conditions, and more. Download the ground plane dipoleinverted v calculator by n2imf. A groundplane antenna is more of less one half of the dipole and mounted above the ground plane. The quarterwavelength, ground plane antenna is made up of one vertical element, called the driven element, and four radials. Paying attention to the effect of the ground plane, using the right materials and matching the impedance of the antenna to. The image antenna just represents all of the currents induced in the ground all around the antenna. The antenna calculator above uses this formula as a starting point to calculate wire lengths for the dipole. There are usually four radials, three being a minimum, but you could use up to six. Vertical antenna ground system experiment 2 rudy severns, n6lf the purpose of this experiment was to quantify the effect of varying the number of radials in the ground systems of several different vertical antennas.
The antenna system requires a ground plane for the radio wave to form. This calculator is designed to give the vertical length height of a particular antenna, for the frequency and wavelength chosen. The antenna can be ground mounted or attached to an insulated pole, which will further improve the hf performance as shown later. Aug 08, 2018 each antenna has a left curve no ground plane and right curve ground plane. To determine the frequency for which this length is 58 wavelength, multiply the frequency by 2. The measurements below are for building a simple dipole antenna. The ground plane antenna is designed for unbalanced feed cables, like a coaxial cable. Amateur radio toolkit for android free download and. This calculator assumes an apex angle of 90 degrees or 45 degrees from hoizontal for each leg and uses an increase of 5%. For contesting, i suspect the vertical would be extremely difficult to maintain an hourly qso run rate higher than the teens, if that, with the antenna in this configuration, without 60 ground radials. Amateur radio toolkit is the best app for ham radio hobbyists. Ground plane antennas are easy to recognize by their appearance. Ground plane and antennas electronics forum circuits. Groundplane antennas for 144, 222 and 440mhz for the fm operator living in the primary coverage area of a repeate r, the ease of construction and low cost of a 14.
This calculator can be used to design a quarter wave ground plane antenna, with radials. The concept of a ground plane is roughly to build a antenna half as long as a normal selfcontained one, then add a mirror so that it looks like a complete antenna from the antenna side of the mirror. Log periodic antenna design calculates the dimensions and spacings of the elements needed to build a log periodic antenna, given tao. Another way to look at vertical antennas 1notes appear on page 32. Vhf and uhf antenna systems 1821 fig23these drawings illustrate the dimensions for the 144mhz groundplane antenna. This calculator is designed to give the vertical length height of a quarter wave ground plane antenna, and the length of each of the four radials often called radiators for the frequency chosen. You can further reduce the height of the antenna by placing a capacitance hat at the top. Another solution to prevent ground loss is the socalled ground plane. In this case, its a multiband antenna the customer is using it can be used from 700 mhz 2700 mhz so the ground plane required could be anywhere from 464 square inches. I wanted high efficiency 40 meter antenna with lowangle radiation.
Use our simple calculator to determine approximate dimensions of materials needed to build a vertical antenna. Fortunately there is an antenna that is inexpensive and simple to build with a minimum amount of parts and tools. Ground currents all around the antenna make the image work. Ground plane antenna calculator resource detail the.
Maple leaf communications antenna calculator vertical. The most widely used formula to calculate the approximate overall length of wire required for a dipole is. T he vertical is a popular antenna among hams who lack the space for a beam or long wire antennas. This antenna has a large load coil right at the top of the antenna followed. It is tough to get better or more simple than this quarter wave ground plane antenna. I use it only on the weekends, primarily for contests, thus it is designed to be raised and lowered with a minimum of fuss. I recently built a quarter wave ground plane antenna, so that i could get back on the 4m 70mhz band. The image antenna for a dipole over perfect earth is a dipole at the same distance below. This antenna is perfect for those hams living in the primary coverage area of the repeater for 2 meter use. Are you looking for a fun and easy antenna project. The term azimuth is commonly found in reference to the horizon or the horizontal whereas the term elevation commonly refers to the vertical. But the construction details are important in order to efficiently convert directivity into gain.
Further simulations indicates that this is true for all other variants of vertical antenna systems too. A comparison was made using the elnec antenna modelling program of the vertical radiation patterns of three antennas. When the antenna is erected and the ground plane is in place, grab your antenna analyzer or vna. If you would rather calculate the length of a fullsize vertical antenna, see the quarterwave vertical antenna calculator. Twayrdio uhfvhf mobile ground plane antenna enhance signal uhf female to pl 259 male connector for car radio mobile transceiver. A quarter wave ground plane antenna has a radiation pattern that produces maximum gain at about 25 degrees and a half wave antenna drops that angle to 20 degrees, and the 58 wave antenna further drops that angle to 16 degrees. For fm radio, wavelength is about 3 m, so the ground plane should be 1.
The formula for calculating the approximate length of a quarterwave vertical antenna is. The basic antenna is a vertical monopole, using elevated radials to complete the ground plane. It has advantages over your folded dipole in several important ways. This indicates a small amount of higher gain compared with the ground mounted antenna. This does not take into consideration the type or size of horizontal reflectors, of even if there is a need for them. Today were going to build a simple ground plane for the vhf 2 meter band. A 12 wave antenna isnt dependent on a good ground, it isnt as prone to lose power in a poor ground situation. By way of background, a 58 wave antenna is the highest directivity, single element, linear antenna that you can construct. An interesting sideeffect i noticed is that under certain conditions a vertical antenna with one radial was substantially more efficient than an antenna with any other number of radials. The vertical axis lines are at 50mhz intervals starting at 800mhz and ending at 1150mhz.