Diskokonusnaja antenna is a characteristic radiator, gave its name to the first part of a multipart name products, equipped with the "ground" of the metal reinforcement or a cone. The partial range of the design will provide a linear vertical polarization wave when moving between the disk and a cone. This is what you need for wireless communication. In addition, consider the revision, which converts the circular polarization device radiator in the direction perpendicular to the disc and opposite to the determination of the earth. Readers will learn how to self-assemble diskokonusnaja antenna.
Scheme discone antenna
Important! Diskokonusnaja Omnidirectional antennas are often used in VHF range. They do not differ a clear gain for this reason.
The theme of today's conversation - diskokonusnaja antenna with your hands. Rumor has it that the first patent under the number 2368663 (USA) took the AG Kandoyan (Kandoian). The advantage of the device is recognized as a wide range of operating frequencies. Of course, increased yields dipole. On a range can usually be connected to the cable without coordination, plus proper design is not critical to the dimensional accuracy. The decimeter have to take solid cone, HF and meter wavelengths, most lack a skeletal form. The disc degenerates into a set of wire-rays to a single center. This reduces the wind load at a wavelength dimensions of the cone and the disk acquire huge importance. Bars 6, 8 or 12.
Attention! Power drive cone and being in opposition.
To drive a certain value is connected core of the wire. The role of the land plays a bundle of metal fittings, if there is no desire to do his own cone. It is understood that the radiation pattern is distorted. Unevenness occurs in the azimuthal direction. A diagram of a typical diskokonusnaja antenna resembles a torus (donut). Wave occurs between the disk and a cone. The range depends on the distance. For example, we give the structure indicated on the site http://elektronika.rukodelkino.com/stati/antenni/35-disko-konusnaya-antenna.html.
The sense operation is already described, for the realization of the frequencies 85 - 500 MHz:
- Disc diameter - 550 mm.
The size and types of disk
- The taper is not given, but the area of the base diameter of 600 mm as the side wall. We believe that the figures easier to cut (out of tin, at least) something suitable.
- The distance from the cone apex to the disk is 100 mm.
- According to estimates of the authors, the total height of the antenna is equal to 620 mm, excluding the thickness of the disc.
Wave device resistance is 60 ohms, prepare align any convenient way. Center conductor is connected to the middle of the bottom disk, cone combined with the screen. Thus, a sort of open waveguide, where the wave is radiated apply. Gain - minus 3 dB in comparison with half-wave dipole. Online calculators to calculate not find a suitable method. Let us analyze our own design. We assume that minimum and maximum distances between the disk and the cone should be related to the boundary wavelength range. Initially, we calculate dimensions:
λmin = 299 792 458/500 000 000 = 60 cm.
lmax = 299,792,458 / 85,000,000 = 3.53 m.
We rely on the values obtained. Divide both sides by four and see what remains. We have 15 and 88.2 cm. We see that the dimensions to anything not tied. According to figures and formulas:
- The apex angle of the cone is 60 degrees.
- side length is a quarter of the maximum operating wavelength or more.
Features of the cone antenna
- The diameter of the cone base calculate, based on the apex angle and the side length. Simply put, it is the length of the part.
- Disc diameter base of the cone is 0.7.
- The cone is cut at the top, to reduce the release cable (coaxial cable).
- The distance from the disc to the truncated cone is 0,3-sectional diameter.
The last two parameters define the upper limiting frequency of the antenna, according to Neil results labor which we have now taken advantage of, diskokonusnaja antenna behaves like a high-pass filter. There is some lower frequency limit, which is calculated on the cone side, where the VSWR is 3. When passing through the limit down SWR starts to grow rapidly, making use of the device impractical. In the operating range setting is gradually reduced to 1.5. The length of the sidewall of the cone take a little more than a quarter of the maximum wavelength. Add that the diameter of the disc does not depend on the angle at the vertex capable differ from 60 degrees.
Compare the number to the above: The calculations show that the side wall is taken to be the minimum wavelength that does not correspond to the book (!). To be sure, we examine the similarity table of literature, to definitively confirm or dispel doubts (site owners are not on that parameter were calculated).
It can be seen that the antenna size decreases linearly with increasing frequency. For example, at 14 MHz nearly twice than at 28 MHz. Consequently, the 85 MHz to find the parameters for the desired proportions (recall that the apex angle in the previously listed data is 60 degrees). 85 divided by 14 = 6. Consequently, the divide ratio obtained for dimensions, yield:
- The apex angle of 60 degrees.
- Diameter and base side length - 91 cm.
- Disc Diameter - 61 cm.
- The clearance between the disk and cone - 4 cm.
The upper frequency is not necessarily 500 MHz, saying that figure depends on the diameter of the cone section. The smaller the hole under the cable, the higher frequency antenna operates. So, we have shown that the trust calculations of the network can not be 100% probability. Perhaps there used some design innovations with unknown data, but rather, the authors cut cone to disc size. Consequently, the lower frequencies will not work.
We can guess how is calculated the maximum operating frequency a quarter wavelength is equal to the distance from the conductor attachment points to disk before the cone section. Just by analogy. Check the facts without portal VashTehnik thesis consider obvious.
Form diskokonusnaja antenna
The attentive reader will note that not all reviews vertex angle is 60 degrees. Why did you choose the specified parameter theorists and experienced practitioners. Conducted research for 50 ohm cable, clearly showing that the angle at the top gives you the widest range where the VSWR is less than 2. In other cases, in the direction of increasing and decreasing, there are various peaks and constriction band. It turns out that an angle of 60 degrees at the apex theoretically justified. If the lower bound unimportant, increase by 10 degrees. VSWR becomes more acceptable, without changing the region of the lower boundary.
As for the skeletal forms, instead of solid cones and discs, it significantly reduces the weight of the product, reduces wind load. Imagine hefty steel products, especially copper! Weight considerable.
Thus, it is shown that demonstrates broadband discone antenna gain is less than that of the vibrator. When this construction is not so sensitive to deviations of dimensions, different comparative complexity. In other words, do diskokonusnaja antenna yourself is possible, but difficult. Let us generalize:
- The key size is considered to be the part of the cone that produces the calculation of the other dimensions.
- The apex angle of 60 degrees to take radio and WiFi.
We promised to show how to improve diskokonusnaja antenna. You are welcome! The disc is not powered from the cable itself, and through the segment of wire constituting a line segment with an infinitely large resistance when passing through a certain cutoff frequency. In the center of the disk is cut an opening through which the live feeds additional drive located above the emitting to the zenith. This design catches virtually any linear polarization, emanating from a point vertically. The need for authors unknown. The example is taken from the literature.
Features diskokonusnaja antennas that may make a gigantic structure that takes on all frequencies. The main thing - the right to carry out the top which is responsible for the upper range. Of course, when approaching a microwave growing requirements for the surface roughness, the light rays, for example, reflected from the mirror. In this light, it is understandable why for products shown such an interest. Half-wave vibrator gives a good gain, but not so plush strip device does not provide. Homemade diskokonusnaja aerial decent size catches almost everything! From all directions. Recommended make discone antenna design and provide good input filter.