In order not to shoot down very technical segment, we propose here a loop antenna resonant high-gain, not only by the height of your frame, but because it is rotating through a single axle and also be mounted as vertical crosshead. This increases, and the sensitivity of its vertices and pretty, and very low noise levels, because the tangents of radio wave, usually horizontal, not reflected in their turns. The Assembly is self-explanatory, not fitting here too much details, but some considerations must be made:

-Give preference to mount this antenna with wooden frame. An experimenter mounted system with PVC pipes and curiously the physical instability of the system showed signs of background noise. The balance of the system produces small variations of tension, which the receiver, it becomes noise;

-Place the variable capacitor on the outside of the magnetic field, i.e. outside of the coil. The "Q" factor of windings in resonance with the variable is vastly more stable and electrically speaking, the antenna becomes resonant with much higher accuracy;

-use a plastic button to operate in variable. The electric charge of our bodies makes the very sensitive variable, what instabiliza the antenna;

-make sure that the shaft and rotating base support are free to rotate. If necessary, place a little oil between backups;

Let's go to the Assembly:

Materials:

2 pieces of wood, cut to the extent of 61 cm long by 4 wide and 2 cm in height.

1 variable capacitor of 1 or 2 sections, whose total capacity exceeds 420 PF. Experiences must be made with other variables.

PS: miniature type capacitors, of American origin were tested, but not presented good yields.

Wood for the base and a second piece, thinner, as swivel base

1 potentiometer that will be broken, where will be used only the shaft and base

4 small screws (2 mm)

37.80 meters of enameled wire, copper or transformer winding, whose section is next to or greater than 1 mm.

The Loop Antenna itself consists in mounting a cross with pieces of wood. The differential of this proposal is that at the base of the vertical frame, there will be a second base, transfixed by the potentiometer shaft, supported by a wooden base. Electrically, this antenna has 17 turns thirty, consuming 37.80 feet of wire on average. Full Coverage of track between 520 to 1710 Khz.

The crosses have 61 cm long by 4 cm wide and 2 cm in height, can be cut directly into a lumberyard or home construction materials to, but if not possible, lower court measures are: 2 cm to the Center crease, which can be found through cross-cutting risks (see illustration). The spacing of the cuts of the adjacent Sciences is 29.5 cm. The depth is 2 cm, as the height (vertical thickness) of wood.

Base:

The winding must be initiated by the swivel base, where already will set the variable capacitor. will be made, 17 wire ties very well stowed, where to complete the 17 will be made another half, where in any of the points, this wire will be taken to the other end of the variable to facilitate the start of winding can be fixed together with the base of the variable and its end, after the soldier isolated polo.

During the winding of coils, variable shaft and screws should be placed in their holes, to prevent breaking the wire into your retrofitting. In the prototype, the variable shaft has 6 inches of length. To make the holes was used a drill for wood number 8. The screws have 2 mm thick by 115 mm overall length. A proportional view of bindings can be seen in the illustration:

Many didn't realize how cold already set up this project and consider themselves happy with their results. In Sao Paulo, SP, Brazil, it was possible to tune perfectly North and Northeast Brazilian broadcasters like Radio Sociedade of Bahia, Radio Pioneira of Teresina and many others. From the outside, was made very easily, the tune of Radio vision Cristiana of Turks and Caicos Islands in the Caribbean, National Radio of Spain, Madrid. A station not too rare but difficult to capture in the large centers was the radio Norway, broadcasting from Kvitsoy, 1,314 Khz whose tune was made at 23:40 hs of Brasília in the Aclimação district, Central/South region of São Paulo. Argentine, Uruguayan and Paraguayan stations became commonplace during the night.

The G5RV is today a very popular dish in the HF bands. Despite widespread use in these tracks, there are some myths and erroneos concepts relating to her. This seems to be a part of your own existence. To light the text "Antenna Compendium, Volume 1, I would like to clarify a few topics about this versatile antenna, tipping, even some myths erroneously created.

Starting let's hear Louis, G5RV, (the AUTHOR of the project) of West Sussex, England, recently deceased with 90 years of age: "the G5RV antenna, with its arrangement of special food, is a multiband antenna fed in the central part, and can operate efficiently in HF, 3.5 to 28 MHz. Its dimensions are specifically designed to operate in areas of limited space (inverted V)but you can "stretch" for reasonably priced 31 metres when fully operated stretched. Additionally, Louis States that, "Unlike multiband antennas, in General, the G5RV drawn in full length version was not designed as a half-wave dipole on frequency lower power operation, but rather as a long-wire with 3/2 wave fed in downtown 14 MHz, where the 10.36 m of open line work as an impedance transformer 1 : 1. This causes the feed, with open lines of 75 Ohm coaxial cables or 50/75 Ohms can lead us to a perfect food in this band, with a consequent very low SWR.

However, in all other HF bands, this section the marrying kind serves as a makeup, accommodating part of stationary were (components of current and voltage), which, in certain instances, operating frequency cannot be completely accommodated in version fully stretched or even V-inverted. The frequency of the central design of the full-sized version is 14.15 Mhz. and the dimension of 31.27 is derived from mathematical expression for the calculation of long-wire antennas, that is:

Considering that the entire system will be taken to the resonance frequency by use of an antenna coupler, in practice, the antenna is cut with 31 metres. As the antenna does not makes use of "traps" or the dipole part of the ferrites, same becomes progressively more long (electrically) with increasing frequency. This effect gives certain advantages over the use of "traps" or because the ferrites, addition of electrical length, the largest blood cells wool vertical polar diagram component tend to decrease as the frequency rises. Thus, from 14 Mhz upwards, good part of the energy radiated in the vertical plane is made interesting angles on DX.

In addition, changes of polar diagram with increasing frequently tend to a half-wave dipole typical in 3.5 MHz,a two-phase half-wave on 7 and 10 MHz and for a long-pattern wire in 14, 18, 21, 24 and 28 MHz. Although the perfect impedance adjustment with open line 75 ohm or 75 Ohm coaxial at the entrance to the section the perfect fit is good at 14 MHz, and may also result in an SWR of 1: 1.8, with 50 Ohm coaxial cable, in this band, the use of a coupler of impedance instances is required in all other bands, because the antenna over the section of perfect fit had a reactive load to feeder, in these other tracks. Thus, the use of the correct impedance adjuster type instances is essential in order to ensure the transfer of maximum power to the antenna, from a typical transceiver that has impedance of 50 ohms (unbalanced) output. Where as the modern transceivers use protection against high SWR, starting his action from relations of 2: 1, the coupler will help, too, to release all its power. Most of these transceivers already possess internally, these automatic couplers, that lend themselves perfectly for this purpose.

Here follows the general theory of operation. As I cannot attach the file transmission diagrams, I follow the text of the ARRL "Antenna Compendium, Volume 1, which is an excellent literature for the fans of antennas (THIS is NOT an ADVERTISEMENT, JUST a NOTE to the ...) Remember that these information are part of the theory and the operation itself will depend upon the installation height over the ground, metal restraints, power lines, trees, etc.

In this range, the antenna acts as a half-wave dipole type shortened, with roughly 5.18 m. total length. The remainder of section of impedance matching instance introduces a reactance inevitable for the antenna, from the point of feed and feed the antenna diagram is effectively equal to a half-wave dipole in this band.

The total length, plus the 4.87 m adapter section transform G5RV in a collinear with 2-phase half-wave, partially folded up. The diagram of antenna irradiation is higher now than a dipole because of its characteristics of collinear. The coupling is slightly degraded due to inevitable reactance level, introduced by the extra length in the adapter section. This reactance can easily be eliminated with an antenna tuner (ATU).

In this range, the antenna works like a collinear 2 half-wave. Is very effective, but the reactance presented to the point of food requires a good antenna tuner (ATU). The diagram of irradiation is basically identical to the standard 7 MHz.

This track is where the G5RV really shines. The antenna is operating as an antenna 3/2 wavelength, fueled by the Center with a diagram of irradiation with many wool blood cells, low irradiation angle, around 14 degrees of elevation, which is very efficient for DX, the most popular of the DX bands. The antenna features a load resistance of 90 ohms, basically not showing reactance. The feed with 50 ohm coax cable will introduce a SWR of 1.8: 1, easily engaged by an antenna tuner.

The antenna works as 2 full waves in phase, by combining a lower angle of irradiation with high bandwidth of a collinear. The load is high impedance, with fairly low reactance.

In this range, the antenna works as a long-wire with 5/2 wavelength, fueled by the Centre. This leads to many wool blood cells, low angle of radiation with high impedance load resistive instance. When properly attuned to the ATU, becomes a highly effective antenna for Dx 's.

In this band, the antenna works as a long-wire, 3 wavelengths, Center-fed. The diagram of irradiation is similar to 21 or 24 MHZ, but with some advantage, due to the effect of collinear obtained by power of two 3/2 wave antennas in phase. The load is high impedance, with low reactance. In part 3, it will be discussed the construction of the G5RV.

Are specified the dimensions of the G5RV fully extended in part 1. The antenna does not need to be necessarily fully extended, but can be installed as a V-inverted. The center of the antenna should be as high as possible, obviously, and the adapter section should get off at right angle to the antenna. It is recommended that the lower section used for the antenna is copper wire of 2.5 mm², although there are antennas constructed with copper wire 1.5 mm² that are operating very well. If the antenna is mounted as V-inverted, the highest angle (inclusive) must not be less than 120 degrees.

It is recommended that the section's adapter built feeder line open, for minimum loss, because it always will in presence of SWR. Faced with the constant presence of stationary were waves, the impedance of the same is not important. A technique of building satisfying memory to the adapter section of line open would make their own acrylic separators, plastic or similar, with low-loss dieletrico. Plastic strips would be cut approximately 5 inches long and 12 mm. wide, notched to fit the threads of 2.5 mm². Pierce the ends of the tabs in a distance of 1 cm from each end, to then be able to tie the wires in your position the spacers should be mounted to each 30 inches.

Another way to do the adapter section would be using tapes to feed the TV antenna, industrial-grade (not manufactured in Brazil ...) of 300 or 450 ohms, whose section of the wires is, at minimum, AWG20 to AWG16. Open Windows on the plastic part, avoiding the tapes if twist am, by occasion of strong winds. Lastly, and less desirable, (although work), is the commercial television tape. The main disadvantage of this type is the durability. Drivers of this tape are typically in diameter 22 to 28, and the quality of the plastic used for the isolation is very low, deteriorating more quickly in the Sun and rain. The biggest advantage is that is readily available in electronic stores, grocery and hardware store. The quality is proportional to the price, if several types are available. Do not use the "heavy" type (2 isolations), because the additional protection is not achieved the desired result, especially in 3.5 or 7 MHz.

The length of the adapter section is half-wave ELECTRICAL OUTLET on 14 MHz. the physical length to use is determined by the following formula:

The speed factor is determined by the type of line and dielectrics properties of their isolation. For the three types of line discussed above, the FV (speed factor) is:

Replacing the FV on formula and calculate to a frequency of 14.15 MHz, you Gets the following lengths for the impedance adapter instances.

The impedance adapter instances is connected to the center of the antenna, and descend vertically at least 6 meters or more, if possible. From there, he can be tied or folded, connecting to the same coaxial cable, taking until the antenna coupler or straight to the equipment if the even own internal Coupler.

In the original article that described the G5RV antenna, published in "RSGB BULLETIN", November 1966, it was suggested that, if a coaxial cable was used to feed the antenna, a balun could be employed to do the required balancing, right at the base of the adapter section. However, more recent experiences and a better understanding of the theory of operation of baluns indicated that such a device was inadequate due to high load reatance, presented at the base of the adapter section. Consequently, We Dont USE A BALUN On G5RV.

If a balun is connected to a line with SWR not less than 2:1, their internal increase losses. the result of this is the heating of ferrite Toroid, with eventually ¼ ente saturation. Operating saturated, the Toroid can distort the RF waves, generating harmonic, and, in extreme cases, with high power, literally destroy the Toroid. An antenna tuner may quietly accommodate variable loads, cancelling the reatance present, reducing the energy of harmonic gifts, which, by the nature of multiband G5RV, could be irradiated. Generally speaking, the existing equipment in modern couplers engage easily all the bands of the G5RV, with exception of 10 Mhz.

Doug DeMaw, W1FB, W1FB's ANTENNA BOOK "of his own, puts the G5RV can be fed with open line, straight to the ATU. If this is done, the antenna will load on all tracks without problems. In this case, the ATU should have an exit to open line, in such a way that make the wedding in all bands. This would assist in operations, laptops where the operator could use an open line and a small tuner designed for this kind of lines, carrying on all HF bands. is an intelligent solution, that would decrease the weight of equipment to be transported in operations laptops. An interesting open line length would be 21.9 metres, allowing whole antenna and the open line were wrapped in a small bucket or spool empty thread, making it easier to transport.

Finally, if you need a good multiband antenna and discrete for your station, give a chance to the G5RV.

The G5RV 160-10 meters, which is a double G5RV (G5RV) x 2, may be used with better performance at the end of the HF spectrum, configuring it as a V-inverted. Electrically, the (G5RV) x 2 is a dipole with 3/2 wave dipole 40 meters, or wave 0.75 per side. In this configuration, it will be bi-directional sharper qualities, with wool directional blood cells more pronounced. To use a V-Inverted as a multiband HF antenna, the user should design it to the middle of the desired range. For example, if you want to use it from 20 to 10 feet, then the angle of pice is computed for the 15-meter band. Using this logic, the length of each side is 2.25 wavelengths, requiring an angle included around 70 degrees.

Using an angle of 70 degrees, will result in an antenna supported by top with two side Joiners, forming a triangle of 3 equal sides (not the Rectangle) with "legs" of 3 supports, forming a triangle, with sides of 31.1 metres and base of 50.9 metres. Is a large triangle with height (highest point) of 17.83 metres. The directivity is along the plane formed by the sides and height, being bi-directional. Approximate gain, is shown in the table below, where they are tabulated winnings for top bands from HF.

This table of winnings is optimistic, based on the angle of the pice is correct for the given side length, which does not occur in practice. The gain will be closer on the 15-meter band, being in the band of 40 m the least approximate, but at most 1 dBd of difference. the values of this table are approaching very a small gain directional antenna and the opening angle could cover, with all certainty, the Brazil, from North to South. (if mounted in direction East-West).

Multiband G5RV antenna is a very popular project in the HF bands. The most popular of them is configured as a 3/2 wave dipole on 20 meters, and works as both a shortened dipole or a long-wire fed as collinear, in other bands. In this configuration, the total length is 31.1 meters, with an adapter section ranging from 8.53 m to 10.36 m. in some cases, it may be too long to adapt is their land and are not all that can convince your neighbors to accept one of his "legs" on your property. In these cases, a version equivalent to half of the previous one, covering 7 to 28 MHz can be used. The reciprocal is true: some amateurs would operate at 1.8 MHz, living on land that accommodate the 62.18 meters required for this version of the G5RV. Here are some dimensions already calculated, which may be useful:

INDUSTRIAL TV TAPE is not found in Brazil. If adopted the option NORMAL TV TAPE (300 OHM TV Ribbon) search for material of good quality. Preferably adopting the first option, which although a little more cumbersome, presents great results, especially when working with higher powers (above 200 watts).

The aforementioned antennas working in 6 meters, often without the aid of antenna tuner!

The antennas listed above, there is a note made by Louis, G5RV, in his article on "ARRL ANTENNA COMPENDIUM, Volume 1, on the version 7-28 Mhz: it refers to the city of Evhan, residence of WB2ELB, which supplies it with a single line, directly built-in coupler your Kenwood and other amateur radio sites, using the 3.5 version-28 Mhzunder the same conditions.

You can build the power line the open line type in many ways. I suggest, personally, that you can use the celeron processor as an insulator, because in addition to their excellent mechanical rigidity has dieletric very good and great durability, even exposed to lightning storms. I've been using the same, in some antennas, for years, without any kind of problems. In case of any doubt, please contact us.