Antenna at 144 MHz. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / VHF antennas

 Comments on the article

The development of local FM networks in the 144 MHz band and the increasing spread of repeaters has led to an increased interest of radio amateurs in omnidirectional antennas with vertical polarization. In addition to the classic quarter-wave pin (GP), an antenna with a radiator length of 5/8 L is very often used. In such an antenna, the radiation pattern in the vertical plane is pressed to the ground, which increases the communication range. What's more, compared to the GP, the 5/8L antenna has a gain of 3dB.

The Korean magazine KARL Monthly (1996, April, p. 55-56) published a brief description of the VHF antenna, which is a common-mode radiator composed of two 5/8L antennas.

From general considerations, it can be argued that such an antenna, with quite acceptable dimensions (total height with a mast of about 3 m), has even more gain than a single 5/8L compared to GP. The described version of the antenna is used by the US Navy (USN STAR GP ANTENNA VHF) and has an operating frequency band of 120 ... 158 MHz with an SWR of not more than 1,3.

Schematically, the antenna is shown in fig. 1. The upper vertical radiator is fed through a phase-shifting line. At an angle of 45 "to the lower vertical radiator, two additional radiators are connected, which expand the operating frequency band. Two counterweights are also located at an angle of 45 ° to the vertical radiators and have a length of approximately 5/8L. The antenna matching element with a 50-ohm feeder is the L1C1 circuit.

The design of the antenna is shown in fig. 2. The upper and lower emitters are connected by a dielectric insert, on which a phase-shifting line is wound. The phase-shifting line is made of insulated copper wire. The diameter of the wire is not indicated in the article, but for general reasons it should be as large as possible (if only the line would fit on the frame). The triangular shape allows it to be wound on a dielectric frame turn to turn. There is also a dielectric insert between the lower end of the lower radiator and a metal mast 1 m long (counterweights are not electrically connected to the mast).

The counterweights and the dielectric insert are clamped between the three-lobed parts (see Fig. 2). Additional lower emitters and counterweights are composite. Sections of pipes with clamps are attached to the three-lobed parts, which include emitters and counterweights, which are made of pipes of a smaller diameter. This makes it possible to change their length in the process of tuning the antenna. The coil is frameless. It is made of bare copper wire with a diameter of 1,5 mm and has two turns with an inner diameter of 16 mm. The capacitance of the capacitor C1 is 5 ... 10 pF.

Since the antenna is factory-made, the vertical radiators have a variable diameter. At the bottom tube, in particular, it varies from 19 to 16 mm (see Fig. 2). In an amateur design, you can, of course, use a regular pipe with a constant diameter.

Publication: N. Bolshakov, rf.atnn.ru

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 Roman horse in Germany 04.08.2010 In a well with a wooden frame 11 meters deep near the German town of Waldgirmes, archaeologists found a bronze head of a horse with remnants of gilding. The life-size head weighs 25 kilograms. Apparently, this is a fragment of a lost ancient Roman statue. The Romans intended to make Waldgirmes the capital of their Germanic colony, but in 9 AD they were defeated by local tribes and evacuated the city. Judging by the rings on the logs of the well log house, the well was dug around the same time.

Other interesting news:

▪ AMD will combine x86 and ARM architectures in one processor

▪ ViewSonic VX28ml 2880" 4K Monitor

▪ Sony PlayStation Portable 2

▪ Boost Voltage Converter NCP5007

▪ The size and shape of the human nose determined by the climate

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Spy stuff. Article selection

▪ article Nowhere except in Mosselprom. Popular expression

▪ article How can macaques cooperatively move objects with their minds? Detailed answer

▪ article Boiler operator. Standard instruction on labor protection

▪ article Balancing device. Encyclopedia of radio electronics and electrical engineering

▪ article About information signs on power lines. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

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

www.diagram.com.ua
2000-2024