HF bridge - panoramic SWR meter. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Antennas. Measurements, setup and matching
Comments on the article
The high-frequency bridge shown in Fig. 1 is assembled according to the classical scheme and does not have any features. When you connect a standard signal generator (GSS) and a "0" indicator to it, you get the usual "ANTENNOSCOPE", a very useful device in amateur radio practice. But, if you connect an amplitude-frequency characteristic (AFC) meter, for example, X1-47 or the like, to the RF bridge, the delight of those who like to mess with antenna matching is guaranteed.
With the usual connection of the antenna-feeder path to the frequency response meter, uninformative oscillatory processes are observed on the screen with a repetition period that is a multiple of the half-wave resonances of the coaxial cable used or any connecting line. Against this background, it is rather difficult to discern the resonant response of the antenna under study, all the more so to make serious measurements, due to the fact that the resonant burst is small in amplitude, poorly distinguishable and practically not informative.
Another thing is obtained by connecting the frequency response meter to the RF bridge. By balancing the RF bridge with a 470 Ohm variable resistor, and full balancing is achieved when it matches the wave impedance of the cable or connecting line, oscillatory processes are completely eliminated on the screen and a clear, high-resolution resonant characteristic of the antenna under study is observed. In fact, the reflection coefficient of a particular antenna-feeder system is displayed, and as you know, it is very clearly tied to the SWR.
Without going into details, in the end, visual and quite reliable information appears on the screen about the resonant frequency and bandwidth of the antenna under study (its frequency response) and, which is very important, you can really assess the degree of matching of the antenna with the cable in the frequency band under consideration.
The available capabilities of the measuring device and the panorama of SWR changes observed on the screen create the conditions for quick and accurate tuning of ANY antenna-feeder system, high-frequency filter plugs of multi-band antennas, and even research and tuning of helical antennas.
Author: G. Bragin, RZ4HK, Chapaevsk; Publication: N. Bolshakov, rf.atnn.ru
See other articles Section Antennas. Measurements, setup and matching.
Read and write useful comments on this article.
<< Back
Latest news of science and technology, new electronics:
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. ... >>
Controlling objects using air currents
04.05.2024
The development of robotics continues to open up new prospects for us in the field of automation and control of various objects. Recently, Finnish scientists presented an innovative approach to controlling humanoid robots using air currents. This method promises to revolutionize the way objects are manipulated and open new horizons in the field of robotics. The idea of controlling objects using air currents is not new, but until recently, implementing such concepts remained a challenge. Finnish researchers have developed an innovative method that allows robots to manipulate objects using special air jets as "air fingers". The air flow control algorithm, developed by a team of specialists, is based on a thorough study of the movement of objects in the air flow. The air jet control system, carried out using special motors, allows you to direct objects without resorting to physical ... >>
Purebred dogs get sick no more often than purebred dogs
03.05.2024
Caring for the health of our pets is an important aspect of the life of every dog owner. However, there is a common assumption that purebred dogs are more susceptible to diseases compared to mixed dogs. New research led by researchers at the Texas School of Veterinary Medicine and Biomedical Sciences brings new perspective to this question. A study conducted by the Dog Aging Project (DAP) of more than 27 companion dogs found that purebred and mixed dogs were generally equally likely to experience various diseases. Although some breeds may be more susceptible to certain diseases, the overall diagnosis rate is virtually the same between both groups. The Dog Aging Project's chief veterinarian, Dr. Keith Creevy, notes that there are several well-known diseases that are more common in certain breeds of dogs, which supports the notion that purebred dogs are more susceptible to disease. ... >>
| Random news from the Archive Discovered a unique mineral from the Earth's mantle
16.11.2021
For the first time in history, researchers from the United States have discovered the mineral davemaoite inside a diamond that was formed in the Earth's mantle.
Named after renowned geophysicist Ho Kwang (Dave) Mao, this mineral is the first example of high-pressure calcium silicate (CaSiO3) perovskite found on Earth.
Another form of CaSiO3, known as wollastonite, is commonly found throughout the world, but davemaoite has a crystalline structure that only forms under high pressure and high temperatures in the Earth's mantle, in the Earth's mostly solid layer, between the outer core and the crust.
Geologists assumed that davemaoite would be a common and geochemically important mineral in the Earth's mantle. But scientists have never found direct evidence of its existence because it breaks down into other minerals as it moves towards the surface and the pressure drops.
However, analysis of a diamond from Botswana, which was formed in the mantle at a depth of about 660 km from the Earth's surface, revealed a sample of a whole davemaoite. As a result, the International Mineralogical Association confirmed davemaoite as a new mineral.
Chauner and colleagues discovered the davemaoite sample using a technique known as synchrotron X-ray diffraction, which focuses a high-energy beam of X-rays at specific points in a diamond with microscopic precision. By measuring the angle and intensity of the returning light, researchers can decipher what's inside, Chauner says.
The davemaoite sample in diamond was only a few micrometers (millionths of a meter) in size, so less powerful sampling methods might have missed it.
Davemaoite is believed to play an important geochemical role in the Earth's mantle. Scientists suggest that the mineral may also contain other trace elements, including uranium and thorium, which release heat as a result of radioactive decay. Therefore, davemaite can contribute to the release of a significant amount of heat in the mantle.
|
Other interesting news:
▪ Electronic map of pastures of Kyrgyzstan
▪ The perfect foam will be developed in space
▪ Graphene water filter
▪ sea turtle chemical cocktail
▪ Electronic nose for clothes
News feed of science and technology, new electronics
Interesting materials of the Free Technical Library:
▪ site section Color and music installations. Selection of articles
▪ article Who seeks - he will always find! Popular expression
▪ article Which vegetables were originally the basis of Halloween lanterns? Detailed answer
▪ article Common beans. Legends, cultivation, methods of application
▪ article Application of loop vibrators in trunk radio communication. Encyclopedia of radio electronics and electrical engineering
▪ article Scheme, pinout (pinout) of the cable for Motorola v3688 phones. Encyclopedia of radio electronics and electrical engineering
Leave your comment on this article:
All languages of this page
Home page | Library | Articles | Website map | Site Reviews
www.diagram.com.ua
2000-2024
Arabic
Bengali
Chinese
English
French
German
Hebrew
Hindi
Italian
Japanese
Korean
Malay
Polish
Portuguese
Spanish
Turkish
Ukrainian
Vietnamese