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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING Plumbing antenna. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / HF antennas In a modern city apartment, using a radio, especially a good one, is almost impossible due to the huge level of interference from a variety of electrical equipment, especially electric vehicles. However, I managed to make an antenna with which listening to the receiver began to be a pleasure. This was achieved with the help of a design based on a central heating pipe or water supply. This use of these tubes has been written on the pages of magazines more than once, but, surprisingly, the idea has never been worked out to the end, and as a result either the effect was incomplete or the idea was emasculated altogether. The design of the antenna is shown in Fig.1. It is put on a vertical section of a water pipe or a heating pipe in a girth, and then in any way, for example, using glue and adhesive tape, a ferrite core is pulled together from a tube TV horizontal scan transformer that has served its purpose. Beforehand, a shielded winding with several taps is wound on one of the halves of the core. That, in fact, is the whole antenna device.
The winding is done like this: - any non-hygroscopic insulating tape is placed on the core in one or two layers (if a dry heating pipe is used, you can take plain paper); - copper or brass foil is placed on the tape in one layer, necessarily with an overlap (overlap) of the turn and a piece of the same insulating tape inserted into this overlap (overlap) so that the screen turns out to be continuous, but there is no short-circuited turn. From the screen draw a conclusion. A screen made of a layer of wire is completely unsuitable; - the winding of connection with taps is laid on the screen in one layer. I have wound 5 + 10 + 20 turns of mounting wire with a cross section of 0,2 sq. mm; - a second foil screen is placed on top of the winding, similarly to the first one, and both screens are connected; - all pins can be provided with pins from a suitable connector, or simply solder a coaxial cable of the required length to them. In this case, the screens and the beginning of the winding (output from the side of five turns) must be connected to the cable screen and connected to the "ground" terminal of the receiver, and one of the outputs of the communication coil (selected for the best performance in your favorite range) must be connected to the central core of the cable and the socket " Antenna" of the receiver. According to my observations, the best work was observed in the shortwave ranges on a five-turn tap, in the medium wave band on a fifteen-turn tap, and on long waves with the communication winding turned on completely. With further improvement of the antenna, automatic switching of these taps can be introduced. But try this, and you won't recognize your receiver, it will work so much better. Due to what, in such a simple design, all the above effects are achieved? 1. An existing grounded fitting is used. This is a lightning-proof design, completely equivalent to the well-known top-fed antennas (the ground point is somewhere far away in the basement of the house). 2. The antenna receives waves with a vertically polarized electric wave vector of a radio transmitter, while horizontally suspended wires of electric vehicles and most household electrical networks radiate interference with a correspondingly horizontal position of the electric wave vector, to which the vertical pipe has a reduced sensitivity. Take a portable receiver with a whip antenna and, walking around the city, analyze at what position of the receiver antenna in space it picks up radio stations better, and at what - interference. 3. When a current induced by a wave flows through a pipe around it in rings (remember the magnetic field of the current flowing through a conductor), a magnetic field is located, and the ferrite core of the antenna concentrates it, directing it into the communication winding. It turns out a kind of transformer from one turn of the primary winding - a pipe and a selected number of turns of the communication winding. 4. Screens protect the receiver from the penetration of interference through the capacitive coupling of the winding with surrounding radiating objects. 5. The higher the class of the receiver used, the better, as a rule, it is protected from receiving signals that penetrate other than the antenna, and the better it will work with this one. A good receiver with the antenna turned off should not receive radio stations, and even more so interference. More about some of the features of this antenna. Figure 2 shows where the antenna device can be placed, and where it is impossible, if the heating battery is bridged by a jumper pipe, and in Figure 3 - if there is no jumper. In this case, it is better to make it artificially using a wire jumper made with a mounting wire with a cross section of at least 1,0 sq. mm with its careful connection to the pipes.
Author: V.Lyamets, Severodonetsk, Luhansk region; Publication: N. Bolshakov, rf.atnn.ru
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