12 Apr 2014

Car antenna for the 144-146 MHz

In one of the amateur radio magazines Russia was published scheme homemade car radio for range 144-146 MHz antenna also for this station . Well, since my blog about the antenna I decided to show you this antenna . And so I had not considered a thief to start write in what magazine was published this scheme automotive radios and antennas respectively for her magazine is " radio ham " 1992 , № 5 . (In Russian) . As can be seen quite unpretentious dish , but its size makes it clear that it is much more effective than in the smaller antenna . This car antenna for the 144-146 MHz range includes : vibrator coil , a magnet , a pair of insulators , it all (except the vibrator ) is placed in the body. The antenna is connected to the transmitter via a coaxial cable with an impedance of 50 ohms. The coil is wound silver-plated wire , wire diameter 3 mm, 4 coils has a diameter of 30 mm and stretched to a length of 40 mm. In the upper part of the housing is an insulator that is inserted into the vibrator antenna coil connected thereto , it is also inserted into the lower outlet in the insulator and connected to the center conductor of the coaxial cable. Below is an insulator under the magnet , whereby car antenna mounted on the roof of your car . Braid is soldered to the body of the antenna. Tuned antenna with a coil , compressed or decompressed its coils antenna configured directly on the roof of the car in the place where it will be located permanently in this place need to change the antenna tuning in section 144-146 MHz . In the presence of the auto antenna tuning devices easier and more tochnoy.Vot and all descriptions . Successful if you travel far and qso.73! yet !

This car antenna for the 144-146 MHz range includes : vibrator coil , a magnet , a pair of insulators , it all (except the vibrator ) is placed in the body


15 Mar 2014

Using shortwave antenna coils and capacitors, as switching elements

Previously considered for shortwave antenna in which as of extension elements used inductors and capacitors (w3dzz), on this page on your blog suggest considering another shortwave antenna published in the Soviet journal Radio hobbyist and part-time engineer I.Adamkovskim (UA3APM) of Moscow region, the article came out in 1969.
The figure shows that the total antenna length of about 40 meters, shortwave antenna operates in the 80,40,20,14,10 meters . Input impedance of 600 ohms , depth of about 20 meters from the surface . As the supply line used ribbon cable 300 ohm. This cable is made of transformer converts the input impedance of the short-wave antenna (600 ohm) to 300 ohms resistance . Why do I need this! ? All banal just - in those years in the USSR was not ready supply line impedance 600 ohms , but there were 300 ohms. If you decide to make this dish one to one , then overcame drawing in which all dimensions are in meters and millimeters. Coil wound carcass without winding diameter of 30 millimeters , 43 millimeters winding length . These wire coils - Copper 1.2 millimeter its diameter . ( Having instrumentation I think will be easy to set up ) . Capacitors used in this shortwave antenna pifarad have a value of 300 with a working voltage of at least 1 kV . After setting up the short- circuit antenna to be sealed .

ps: capacitors and coils in the shortwave antenna play the role of automatic switches.


shortwave antenna

1 Feb 2014

Two wire antennas range of 1.9 MHz

These two simple wire antennas are designed to operate in the 1.9 MHz amateur band . They are connected to a coaxial cable with a characteristic impedance of 50 or 75 ohms. Total length of the wire antenna should be: for the first figure of 38 meters, the second slightly longer than 43 meters . Of both figures show that the wire antenna for 1.9 MHz band as it split into two sections - the antenna itself and reduced to connect the matching device and coaxial cable. Here it should be noted that the ratio of these areas antenna wires can be anything, the main thing here is the total length of the antenna wire and the length of these sections can be arbitrary. Inductance for the first wire antenna is 13 micro Henry , she performed on a frame of 50 mm diameter , has 20 turns of copper wire with a diameter of 0.8-1.0 mm. Winding length of 50 mm. In this design, the wire antenna for 1.9 MHz is much more difficult to make (or find) the variable capacitor ( in terms of its dielectric strength ) , to transmit power to 10 watts , you can use a regular capacitor . Setting a first embodiment of a wire antenna for a range of 1.9 MHz start with the settings in the resonance of the capacitor at the operating frequency , on the selection of the number of coil turns achieve minimum SWR. Antenna in the second picture has an active component of the input resistance of about 50 ohms. Please compensate capacitor C reactive component of the input resistance (it has an inductive character ) , and then pick the length of the antenna SWR , each time adjusting the capacitor C. Because of the high input impedance of this antenna is more efficient than the first wire antenna pattern but the latter is easier to setting , as it requires careful selection of the overall length of the antenna. For these two wire antennas for a range of 1.9 MHz required good " grounding system " , in the simplest case, a system of " earth " should be supplemented by at least one counterweight to the maximum possible length ( but not less than 5 m) .
wire antennas range of 1.9 MHz

wire antennas range of 1.9 MHz

18 Jan 2014

Anti noise wire antenna for MW and LW bands

On this page of their site, I want to tell you that I found this description of the Russian Internet wire antenna , which I was very interested . This wire antenna for observers (SWL). What I'm interested in this dish: the first - is its simplicity , the second - that I have the opportunity to set it up , and the third - this antenna anti noise , well, that this fourth antenna operates in the long and medium waves . About the last ( fourth ) will say that I particularly recently started exactly like the medium wave and long wave bands and radio stations operating amplitude modulation. Real romance for radio amateur observer why I ceased to please ssb I do not know , but it seems just tired of these unnatural narrowband signals. And maybe that's why I decided to turn its attention to the low-frequency ranges . Of course these bands in Russia is very much noise but may be due to its two digital radio WinRadio and SDR-IQ that will work with this wire antenna I get to grips with this problem. This summer I will try to install this antenna . And so I will not steal someone else's article and pictures here and just giving this < link > to it . And to describe briefly what there are articles and pictures I think you will understand even though they are in Russian, everything is clear . For a full translation of an article on this wire antenna , you can use < translator google>. It states that the use of an antenna that receives the magnetic component of the electromagnetic field to reduce the noise level is almost 100 times ! Wire antenna in question in the article is very close to the ground , you can even put it in general . Admission to this antenna is carried out with the direction perpendicular to the plane of the frame antenna , ie reception of the station most distant from the point of finding antenna (similar vertical emitter ) . Due to the fact that the wire antenna is very low to the ground resonance it is missing, it is obtained as a shunt to ground. Dimensions of this antenna is to be performed for the highest frequency band ( wire antenna dimensions for a range of communication and there are doors ) . There's also said that raising it too high , too, do not need , it will lead to a drop in antenna gain . The antenna connected to two coaxial cables , and there are drawings of how to connect these cables to the symmetric and symmetric receiver input . The author writes that he took the radio communication range and doors to all on a very short antenna , but with a short wire antenna becomes difficult to receive distant stations . Generally, if it is not clear that you will be from the translation please contact me by e-mail envelope is below , we will try together to understand this wire antenna for SWL.

(here the translation of the text in the picture)

11 Jan 2014

Wire loop antenna for a range of 1.9 MHz

Compared with the antenna for the transmitter antenna to the receiver is not too difficult , even for a band as 1.9 MHz . Typically, such wire antenna is a frame that consists of one or several coils . Wire loop antennas have two distinct minimum when the signal directed perpendicular to its plane . Suppression of radio signals and interference are the side of the loop antenna can reach about 30 dB ( five points on the scale S!). An embodiment of the wire loop antenna shown in Fig . The antenna has three turns ( a square with sides 1.5 meters ) , forming a frame, and one round of communication . Any wire diameter , the usual equipment wire. The frame is placed in the electrostatic shield , open at the top. The screen can be made of braided coaxial cable , fixed to the frame cross member of the dielectric. Framed wire antenna is tuned to the operating frequency of the capacitor C1 , which must be protected moisture. To frame the receiver is connected via coaxial cable with a characteristic impedance of 50 ohms.
Wire loop antenna for a range of 1.9 MHz