Antennas. Measurements, adjustment and coordination. Schemes, articles of the Free Technical Library

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Antennas. Measurements, adjustment and coordination. Schemes, articles, descriptions

Free library / Schemes of radio-electronic and electrical devices

Antennas. Measurements, setup and matching

We recommend reading in our Free Technical Library:

Multirange dipole

HF Antenna Section. Finnish radio amateur Pekka Pyukko (OH1NE) from Turku sent a description of his multi-band dipole designed to operate in the 3,5, 7, 14, 21 and 29 MHz bands to the editor. According to the author of the letter, the dipole gives good results at 3,5, 7, 14 and 29 MHz (with a low standing wave ratio). Sufficiently good results and a low standing wave ratio were obtained at 21 MHz. The dipole of the radio amateur OH1NE is shown schematically in fig. 1 ... >>

Single coil induction metal detector

Section Metal detectors. The quartz oscillator is a source of rectangular pulses, from which a signal is subsequently formed that enters the sensor coil. The oscillator signal is divided by frequency by 4 using a ring counter on flip-flops. According to the ring circuit, the counter is designed so that two signals F1 and F2 can be generated at its outputs, shifted relative to each other in phase by 90 °, which is necessary to build a discriminator circuit. A rectangular signal (meander) is fed to the input of the first integrator, the output of which is a piecewise linear sawtooth voltage. The second integrator makes a signal from the saw, which is very close in shape to a sinusoidal one and consists of half-waves of a parabolic shape. This stable amplitude signal is fed to the power amplifier, which is a voltage-to-current converter loaded on the sensor coil. The sensor voltage is no longer stable in amplitude, as it depends on the signal reflected from metal objects ... >>

Telemechanics for switching loads by telephone

Section Telephony. The device allows, by means of a call to the phone, to turn on and off three loads independently of each other. For example, in the absence of the owners, you can turn on and off the light in the apartment, thereby imitating their presence, feed the fish, etc. Power of each load = 120 W, Upp. = 10...12 V ... >>

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Articles on setting up and matching antennas

Articles on adjustment of antennas; schemes for setting up antennas; antenna adjustment descriptions: 28 articles

All articles on antennas

Latest news of science and technology, new electronics:

Air trap for insects 01.05.2024

Agriculture is one of the key sectors of the economy, and pest control is an integral part of this process. A team of scientists from the Indian Council of Agricultural Research-Central Potato Research Institute (ICAR-CPRI), Shimla, has come up with an innovative solution to this problem - a wind-powered insect air trap. This device addresses the shortcomings of traditional pest control methods by providing real-time insect population data. The trap is powered entirely by wind energy, making it an environmentally friendly solution that requires no power. Its unique design allows monitoring of both harmful and beneficial insects, providing a complete overview of the population in any agricultural area. “By assessing target pests at the right time, we can take necessary measures to control both pests and diseases,” says Kapil ... >>

The threat of space debris to the Earth's magnetic field 01.05.2024

More and more often we hear about an increase in the amount of space debris surrounding our planet. However, it is not only active satellites and spacecraft that contribute to this problem, but also debris from old missions. The growing number of satellites launched by companies like SpaceX creates not only opportunities for the development of the Internet, but also serious threats to space security. Experts are now turning their attention to the potential implications for the Earth's magnetic field. Dr. Jonathan McDowell of the Harvard-Smithsonian Center for Astrophysics emphasizes that companies are rapidly deploying satellite constellations, and the number of satellites could grow to 100 in the next decade. The rapid development of these cosmic armadas of satellites can lead to contamination of the Earth's plasma environment with dangerous debris and a threat to the stability of the magnetosphere. Metal debris from used rockets can disrupt the ionosphere and magnetosphere. Both of these systems play a key role in protecting the atmosphere and maintaining ... >>

Solidification of bulk substances 30.04.2024

There are quite a few mysteries in the world of science, and one of them is the strange behavior of bulk materials. They may behave like a solid but suddenly turn into a flowing liquid. This phenomenon has attracted the attention of many researchers, and we may finally be getting closer to solving this mystery. Imagine sand in an hourglass. It usually flows freely, but in some cases its particles begin to get stuck, turning from a liquid to a solid. This transition has important implications for many areas, from drug production to construction. Researchers from the USA have attempted to describe this phenomenon and come closer to understanding it. In the study, the scientists conducted simulations in the laboratory using data from bags of polystyrene beads. They found that the vibrations within these sets had specific frequencies, meaning that only certain types of vibrations could travel through the material. Received ... >>

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