Interesting that you mentioned loops and showed a picture of a magnetic loop. I have made a few magnetic loops in my time, but never over 146mhz as it is too hard to make them and the capacitor to make them resonate. Very temperature dependant and very high Q. I would love to see a magnectic loop for wifi. At 2.4 ghz the loop would be 5 to 7mm in diameter. Most likely it would be a heater as i dont think the rf would radiate out. But would love to be proven wrong.
What is radiation? How is a transverse wave produced? What is refraction? Light and radio waves are electromagnetic waves comprising electric and magnetic field pulsations or variations in strength at each point in the space. It is a form of radiated waves of pulsating electric and magnetic fields. They are produced by accelerated electric charge which produce a transverse electric field which propagates outward from the accelerated charge. The radiated fields constitute a wave travelling through space. The fields don't travel, the wave does. The fields pulsate in strength. This is best visualised by a rope, one end of which is fixed to a wall and the loose end held some distance away. The loose end when moved up and down creates a wave travelling. Notice how the molecules of the rope near the wall have not travelled to the loose end. The snake-like shape in the form of a sinewave and travelling movement you see is the overall effect of the up and down movement of the molecules of the rope. The same happens with the strength of electric and magnetic fields of radio waves and light. There are no sinewaves in space! It is the strength of the electric field say, which we plot of a radio wave which has a pattern of a sinewave. When a radio wave or rather the fields of the wave encounter matter, they set into motion the atoms in the material. The acceleration they produce of the charges that make up the atoms and molecules in matter, produce electromagnetic waves and these are reradiated fields. The incident and reradiated fields combine to produce a resultant wave. These resultant waves constitute the fields in reflection and refraction. Before learning about sinusoidal currents, voltages and electromagnetic fields it would be instructive to learn about current and the conduction process at the fundamental level as in these two videos i. th-cam.com/video/TTtt28b1dYo/w-d-xo.html and ii. th-cam.com/video/8BQM_xw2Rfo/w-d-xo.html Engineers are so used to thinking and visualising currents as differential-mode in circuit analysis that they find it hard to switch their thinking to common-mode currents and its uses in designing high impedance antennas. They can be generated internally in circuits and in antennas such as the folded dipole antennas like the Yagi antenna. The last frame of video 1 contains in the References textbooks 3 and 4 which discuss antennas (dipoles) and wave propagation and includes topics on reflection, reradiation and scattering using the unified approach with the help of sequential diagrams. Also discussed in textbook 4 is the generstion of common-mode currents in two-wire cables which is useful in understanding the operation of the folded-dipole. Watch the following videos to get an idea of radiation by an accelerated charge and an oscillating charge. Video 1 Field lines for an oscillating particle in 2D www1.astrophysik.uni-kiel.de/~hhaertel/Videos/oscillation-2d.mp4 Video 2 Field lines for an oscillating particle in 3D www1.astrophysik.uni-kiel.de/~hhaertel/Videos/fast-osc-particle.mp4
Thanks for the video. However, it was too fast for me. I actually checked if I was playing it at 1.5x I am a non-native English speaker with above-average English (or so I think).
What topics do you want to learn about next? Let us know in the comments.
Can you talk about Cross Polar Discrimination ?
I want to understand how current is produced inside an antenna if it's not closed circuit
Really good job here buddy. Enjoy the part when you explain what these are used for. I'm sure you're very loved.
Interesting that you mentioned loops and showed a picture of a magnetic loop. I have made a few magnetic loops in my time, but never over 146mhz as it is too hard to make them and the capacitor to make them resonate. Very temperature dependant and very high Q. I would love to see a magnectic loop for wifi. At 2.4 ghz the loop would be 5 to 7mm in diameter. Most likely it would be a heater as i dont think the rf would radiate out. But would love to be proven wrong.
how do you change the frequency of radiation/reception?
Best explanation for introduction to antenna.
Aren't radiometers antennas that do not transmit EM waves?
what exactly do you mean by a radiometer?
@@Rfelements For example, an L band microwave radiometer. RADAR emits and receives signals, radiometers only receive.
@@juliazhang3600 Radiometers are devices - circuitry + antenna, but principally yes, they only receive..
Or 300 m! Which one?
I naively thought understanding antennas would be simple. So wrong. Thanks for the video.
muy interesante saludos desde colombia
What is radiation? How is a transverse wave produced? What is refraction?
Light and radio waves are electromagnetic waves comprising electric and magnetic field pulsations or variations in strength at each point in the space.
It is a form of radiated waves of pulsating electric and magnetic fields.
They are produced by accelerated electric charge which produce a transverse electric field which propagates outward from the accelerated charge. The radiated fields constitute a wave travelling through space.
The fields don't travel, the wave does. The fields pulsate in strength.
This is best visualised by a rope, one end of which is fixed to a wall and the loose end held some distance away.
The loose end when moved up and down creates a wave travelling.
Notice how the molecules of the rope near the wall have not travelled to the loose end.
The snake-like shape in the form of a sinewave and travelling movement you see is the overall effect of the up and down movement of the molecules of the rope.
The same happens with the strength of electric and magnetic fields of radio waves and light.
There are no sinewaves in space! It is the strength of the electric field say, which we plot of a radio wave which has a pattern of a sinewave.
When a radio wave or rather the fields of the wave encounter matter, they set into motion the atoms in the material. The acceleration they produce of the charges that make up the atoms and molecules in matter, produce electromagnetic waves and these are reradiated fields.
The incident and reradiated fields combine to produce a resultant wave.
These resultant waves constitute the fields in reflection and refraction.
Before learning about sinusoidal currents, voltages and electromagnetic fields it would be instructive to learn about current and the conduction process at the fundamental level as in these two videos
i. th-cam.com/video/TTtt28b1dYo/w-d-xo.html and
ii. th-cam.com/video/8BQM_xw2Rfo/w-d-xo.html
Engineers are so used to thinking and visualising currents as differential-mode in circuit analysis that they find it hard to switch their thinking to common-mode currents and its uses in designing high impedance antennas.
They can be generated internally in circuits and in antennas such as the folded dipole antennas like the Yagi antenna.
The last frame of video 1 contains in the References textbooks 3 and 4 which discuss antennas (dipoles) and wave propagation and includes topics on reflection, reradiation and scattering using the unified approach with the help of sequential diagrams. Also discussed in textbook 4 is the generstion of common-mode currents in two-wire cables which is useful in understanding the operation of the folded-dipole.
Watch the following videos to get an idea of radiation by an accelerated charge and an oscillating charge.
Video 1 Field lines for an oscillating particle in 2D
www1.astrophysik.uni-kiel.de/~hhaertel/Videos/oscillation-2d.mp4
Video 2 Field lines for an oscillating particle in 3D
www1.astrophysik.uni-kiel.de/~hhaertel/Videos/fast-osc-particle.mp4
Hi.i m sorry because mi englis is bad. But lambda=c/f. So if f=10MHz than lambda is 30 cm!! Not 30 mm.
Hello. At 10MHz is 30 meters. Cheers.
Thanks for the video. However, it was too fast for me. I actually checked if I was playing it at 1.5x I am a non-native English speaker with above-average English (or so I think).
We've slowed it down in newer episodes.. but you can also slow the playback down, YT now has that option thankfully/
Thanks
Lots of good info, but too quick😂
Great, I m Sajid from Pakistan.
hi Sajid, greetings to Pakistan! 😋
Very good
Thanks, make sure to subscribe and like the video so you don't miss any future episodes!
👍
tq