Ringo antenna . Omnidirectional Vertical Antenna Band of 11 meters . Among the projects that radio amateurs can carry out without much difficulty , especially those that make transmissions in the 11-meter band, is the construction of a truly interesting antenna .
Summary
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- 1 Features
- 2 Advantages
- 3 Structures
- 4 Sources
characteristics
It is a very efficient antenna, both for emission and reception in this frequency range within 27 MHz . This vertical type antenna is known by the name of Ringo antenna; It provides a gain of approximately 4 decibels , which is equivalent to a 2.5-fold power increase. This means that a 2-watt transmitter will be picked up with the same intensity as a 5- watt one .
Advantage
The Ringo antenna has the same advantages as a vertical telescope , especially in terms of omnidirectionality, that is, the ability to transmit power in all directions, although its performance is significantly higher. In addition, it has the characteristic of a reduced angle of radiation , which offers the possibility of reaching a distance significantly higher than what is achieved with a telescopic antenna, taking advantage of only the direct wave that is emitted at a higher distance, thus reducing also the so-called zone of silence .
These advantages will be evident not only in transmission, but also in reception. Indeed, it will be possible to verify that radio stations that normally arrive with great weakness can be picked up at much higher power levels using this antenna. Finally, this antenna is equipped with a very efficient impedance adapter, which allows a perfect match between the impedance of the antenna and the transmitter.
Structures
The antenna consists of a telescopic body 481 cms of length , which is made with tubes aluminum and of a diameter which is chosen so that the entire assembly enjoys a certain robustness. You can start at the base with a tube with a diameter of 20 to 25 mm (tube S ), and then choose other tubes with suitable diameters, which allow each of them to be inserted precisely in the previous one, until reaching the indicated height of 481 cms. (See Fig 1).
Fig 1
It should be checked at the time of inserting a tube into the other that the surfaces of contact are perfectly polished, so as to provide a contact electric suitable. The various tubes, except the last one, can be fixed with screws or aluminum rivets . If we want the antenna to be able to be completely disassembled, we will use clamps at each joint.
To achieve the total length of 481 centimeters , it must be distributed among the different tubes, leaving an additional 15 or 20 centimeters in each one so that each one enters the next, forming a telescopic structure similar to that of the antennas of the Portable radios. At the upper end of each tube should be performed on both sides, a cut with a saw .
At that junction point, adjustable clamps of the type used to splice hoses and pipes in automobiles or industry should be installed . These clamps must be of an anticorrosive material in order to avoid [Oxidation | oxidations]]. (See Fig 2).
Fig 2
The last tube of the antenna must be extensible with respect to the preceding ones so that the length of the antenna can be varied until all standing waves are completely eliminated.
The impedance adapter, consisting of an 8mm diameter aluminum tube, bent so as to form a circumference of approximately 290mm in diameter, will be installed at the bottom end S of the tube . To bend the tube can proceed very simply, using a wheel of wood as template. (See Fig 3).
Fig 3
A = clamp metal binding between the wire E and circular tube M . E = thread copper 2mm connecting the terminal the coaxial cable to the bracket A . F = flange connecting the end of the tube M to the vertical antenna S . G = clamp joining the other end of the tube M to the lower tube piece of G . H = terminal for coaxial cable. M = circular tube of the impedance adapter. N = tubeplastic or rubber which isolates the vertical antenna S of the lower piece G .
Fig 4
Making coaxial cable it is attached to the center of the clamp G , or whatever it is connected to one end of the tube M to the lower support, always indicated with the letter G . The diameter of the circular tube should be 290 mm. One end of the circle must be attached by the clamp F to the base of the top tube, while the other will bind through the clamp H to the apex of the lower tube, indicated by the letter G .
This union must be made by means of aluminum rivets .
It should be emphasized that the two pipes in question must be isolated from each other, which can be achieved easily by placing on the tube S a plastic tube, of rubber or Teflon (indicated by N ) that leave uncovered the pipe S at minus about 10 cms. The two tubes were then introduced into the tube G .
The wire E must be moved in the adjustment phase approximately 40 cm in the tube M , so that it is never in contact with the vertical tube.
Once removed standing waves, the thread E may be fixed or welded on the tube M . (See Fig 5).
Fig 5
In the lower clamp indicated with the letter G , a female nut for coaxial cable ( H ) will be placed approximately in the middle, through which we will connect the antenna to the transmitter . The central terminal will be welded with a 2 mm copper wire, which will be joined by means of a sliding piece, made of aluminum ( A ) or by any other metallic system. In any case, this connection must be able to slide over M , so that in the adjustment phase the desired adaptation of impedances can be carried out .
The antenna will be fixed on an insulated tube. In other words, the bottom end of tube G will need to be isolated from the bracket. For this, the antenna will be fixed to a wooden base , or the same system that serves to isolate tube G from tube S will be applied .
Tuning the antenna is extremely simple if you have a standing wave meter. It will be enough to apply the meter in series with the coaxial cable connecting with the transmitter, progressively fix clamp A along tube M , until the instrument indicates zero . At this point, the adaptation for the desired frequency range will have been achieved
Fig 6
If turning M does not obtain a perfect indication of zero, you can intervene in the length of the antenna, moving the last element, leaving it at 477 or 485 cm, and then turning M again , until obtaining the desired zero indication.
Once the adaptation that is to be provided to the antenna impedance value required, it must be fixed stably to the circle M .
Under these conditions, the antenna will be prepared to transmit and receive signals in the 11-meter band.
The terminal for coaxial cable is fixed, as already seen in the center of the bracket G . The central terminal of the same is soldered to the wire E which connects to the adapter cirnular M .