Menu English Ukrainian russian Home

Free technical library for hobbyists and professionals Free technical library


ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Schemes of radio-electronic and electrical devices

YAGI antenna at 28 MHz. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / VHF antennas

Comments on the article Comments on the article

The presented 3-element YAGI antenna is designed by SP1CLY.

Its design (Fig. 1) is very simple and does not require scarce materials. With exact observance of all dimensions, the adjustment is reduced to adjusting the capacitor C1 to a minimum SWR.

28 MHz YAGI Antenna

The maximum capacitance is C 1 - 100 pF; instead, you can use a piece of coaxial cable that is open at the end.

Literature

  1. "QTC" №5/6 1993

Publication: cxem.net

See other articles Section VHF antennas.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

A New Way to Control and Manipulate Optical Signals 05.05.2024

The modern world of science and technology is developing rapidly, and every day new methods and technologies appear that open up new prospects for us in various fields. One such innovation is the development by German scientists of a new way to control optical signals, which could lead to significant progress in the field of photonics. Recent research has allowed German scientists to create a tunable waveplate inside a fused silica waveguide. This method, based on the use of a liquid crystal layer, allows one to effectively change the polarization of light passing through a waveguide. This technological breakthrough opens up new prospects for the development of compact and efficient photonic devices capable of processing large volumes of data. The electro-optical control of polarization provided by the new method could provide the basis for a new class of integrated photonic devices. This opens up great opportunities for ... >>

Primium Seneca keyboard 05.05.2024

Keyboards are an integral part of our daily computer work. However, one of the main problems that users face is noise, especially in the case of premium models. But with the new Seneca keyboard from Norbauer & Co, that may change. Seneca is not just a keyboard, it is the result of five years of development work to create the ideal device. Every aspect of this keyboard, from acoustic properties to mechanical characteristics, has been carefully considered and balanced. One of the key features of Seneca is its silent stabilizers, which solve the noise problem common to many keyboards. In addition, the keyboard supports various key widths, making it convenient for any user. Although Seneca is not yet available for purchase, it is scheduled for release in late summer. Norbauer & Co's Seneca represents new standards in keyboard design. Her ... >>

The world's tallest astronomical observatory opened 04.05.2024

Exploring space and its mysteries is a task that attracts the attention of astronomers from all over the world. In the fresh air of the high mountains, far from city light pollution, the stars and planets reveal their secrets with greater clarity. A new page is opening in the history of astronomy with the opening of the world's highest astronomical observatory - the Atacama Observatory of the University of Tokyo. The Atacama Observatory, located at an altitude of 5640 meters above sea level, opens up new opportunities for astronomers in the study of space. This site has become the highest location for a ground-based telescope, providing researchers with a unique tool for studying infrared waves in the Universe. Although the high altitude location provides clearer skies and less interference from the atmosphere, building an observatory on a high mountain poses enormous difficulties and challenges. However, despite the difficulties, the new observatory opens up broad research prospects for astronomers. ... >>

Random news from the Archive

Mathematicians have developed the perfect espresso coffee 21.01.2020

Scientists have created a mathematical model for making espresso, which showed the optimal values ​​​​of parameters that allow you to achieve repeatability of taste, while saving coffee. The key recommendation is to grind the beans to a certain size that is coarser than what is used today in most cases.

Espresso is one of the most popular ways to brew coffee. To obtain this drink, hot water under pressure is passed through ground roasted grains. Despite the prevalence of this method, the result of its application often differs from time to time. As a rule, this is attributed to the human factor, although there was no full evidence of this.

There are official guidelines for brewing espresso. According to them, the final volume of the drink should be from 25 to 35 milliliters, while water should be supplied under a pressure of 9 bar, at a temperature of 92 to 95 degrees Celsius and for 20-30 seconds, and the required mass of grains for one cup should be in range from 7 to 9 grams. However, many coffee shops deviate from these rules, as modern coffee machines allow you to adjust not only these parameters, but many others.

The final taste of coffee is determined by the ratio of concentrations of approximately two thousand chemical compounds contained in the beans. It is generally believed that the smaller the grind, the better the drink will be, as this increases the area of ​​\uXNUMXb\uXNUMXbcontact between coffee and water. However, in reality, it is very difficult to brew the same tasting espresso several times in a row.

Jamie Foster of the University of Portsmouth and colleagues have developed a new mathematical model for espresso brewing that offers an ingenious explanation for quality variability. According to the results of the work, the amount of brewed coffee depends non-linearly on the degree of grinding: as the grain size decreases, the dissolution productivity increases, but after a certain value it starts to fall.

The authors did not use direct modeling of all physical and chemical processes during the flow of water through coffee, but modified well-developed methods for simulating the movement of charged particles in lithium-ion batteries. It turned out that too fine grinding leads to partial clogging of the filter and a decrease in the proportion of the dissolving substrate.

Ultimately, the authors suggest using not the finest grind, adding slightly fewer grains and using less water. According to the researchers, this strategy results in saving money and resources, and ensures the reproducibility of the taste of the drink. However, this does not mean that there is only one parameter setting that produces the best coffee, as taste preferences vary from person to person. In some cases, it may be necessary to mix several brews in an optimized way to reproduce the preferred taste.

Other interesting news:

▪ Anger Pill

▪ Smart speakers help save lives

▪ Residents of countries with migrants smile more often

▪ Technology for creating artificial joint selfies

▪ Liquid with piezoelectric effect

News feed of science and technology, new electronics

 

Interesting materials of the Free Technical Library:

▪ section of the site Your stories. Article selection

▪ article Activator for seedlings. Tips for the home master

▪ article Who eats more than others? Detailed answer

▪ Daikon article. Legends, cultivation, methods of application

▪ article Current sensor on the Hall element. Encyclopedia of radio electronics and electrical engineering

▪ article Separate the hoops. Focus Secret

Leave your comment on this article:

Name:


Email (optional):


A comment:





All languages ​​of this page

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua

www.diagram.com.ua
2000-2024