I will say this... most of the ham videos on the interwebs talk in so much code... that i think they forget there are people who know nothing about the hobby (me) that are trying to learn. So when somebody breaks down definitions (and more importantly, functions and practical applications)... i get jazzed. So thanks!
OK, so SWR is a measurement of reflected power; so how and why is the power "reflected". Yes, I know it has to do with tuning the antenna so that the impedance matches between the antenna and the radio, but more directly, WHAT reflects the power, and how does tuning the antenna to its resonant length prevent that? Would installing a resistor at the ends of the antenna prevent this reflection?
Your doubt is so profound that I don't even know if most people can imagine how difficult it is to answer "why things are". Children generally want to know the why of things, and not just examples, effects or analogies. And in fact, science still hasn't figured out why a lot of things, actually. The more you understand, the closer you get, but the real reason is still missing. So in the case of reflected power, what I know is that the power comes from the voltage and current of the signal source varying. And then we have current and voltage varying and a transmission medium (the line), and this we call a wave, in this case electromagnetic. And this type of wave has many analogies with other waves, and has much of its behavior explained in Maxwell's electromagnetism equations. He noticed relationships between some existing theories and brought this knowledge together. In his development there is one that shows the behavior of an electromagnetic wave traveling in a medium and that encounters a change in this medium, such as a fault, a discontinuity, a change of medium (type from air to water, or a coaxial cable to a dipole antenna), or a screen (obstacle). And it turns out that this voltage and current wave, which is also a varying Electric and Magnetic field, when it goes through these types of changes in the environment, each field interacts differently with this change in the environment. But in any of these changes, both the Electric and Magnetic fields interact with this change, and part of the energy that these fields carry interacts with the material of the media and this interaction causes a macro effect, where it appears that the wave has passed forward, but a part of it returns the way it came. This Sometimes the wave that passes ahead passes with its fields unchanged in relation to the phase, other times it does not. The same occurs with the fields of the returning wave. And this occurs whenever this wave goes through these changes in environment. Another important issue is that everything that is at stake here also depends on the frequency that this wave has. If the wave is pure, we can think of just one frequency and that makes it easier to imagine things. The way in which the Electric field and magnets interact will be different, but the truth is that we do not have signals of this purity. We always have more content in the signal, which means that reality is of a compound complexity, and we need to understand simple things to be able to try to glimpse a little of reality. If you keep asking yourself, why do the Electric and Magnetic fields interact in this way when their transmission medium changes, then you will be going even deeper, arriving at Quantum Field Electrodynamics, a Theory of Physics where almost everything ends up. She tries to explain the interaction of matter, but even she is still unable to explain the truth.
Cos my field is in computers, i have some idea, , your wondering, what the hell is an SWR, SWR stands for "Standing Wave Ratio", the transmitting signal travels along the antenna (FORWARD) and refects at the end, returning down the antenna (REFECTED), the forward signal interferes with the reflected signal causing constructive or deconstructive interference, differant lengths create differant phases along the antenna, when a peek meets a peek there is max emission, and when a peek meets a trough there is zero emission, an SWR ratio of 1:1 is perfect constructive interference, where the cycle appears STATIONARY on the antenna, creating a perfect waxing and waning electo-magnetic field, as the electric field collapses, the magnetic field increases and vice versa, , ,Without that load absorbing energy, the energy instead appears as a high voltage or high current somewhere which may not be equipped to handle it, , So basically, an ideal 1:1 SWR will produce a low 50ohm resistance match where the antenna does work, the SWR is relatively constant along the feedline, the impedance will vary along the line unless it is perfectly terminated (that is, the SWR is 1.0 : 1). This is an important concept for impedance matching, because with a high SWR, the impedance at the final output transistor load inductor could be mainly higher, or lower than 50 ohms, and produce a high current that damages the finals, , ,
I too would love to know if an ATU will recover the lost power and the antenna will radiate it, or will the LC circuits in the ATU simply absorb the reflected power and protect the TX finals?
I will keep this simple so I may not be technically correct. 1) An "antenna tuner" does not increase antenna gain. 2) It does make the transmitter think everything is okay so it doesn't reduce TX power to protect the radio. 3) It does help with receiving signals also. This part seems like magic to me because it doesn't fix the resonance of the antenna.
Howdy. I would think that a tuner provides a conjugate output impedance to the transmission line + antenna impedance. This, I understand, is the best power transfer setup. So, in my mind, a tuner will recover much of the reflected power and send it back to the antenna to radiate. A tuner is an impedance trasformer. It transforms 50 ohms purely resistive to the coax. + antenna conjugate impedance. My thinking is that a tuner does not bring the antenna into resonance. But it brings the coax. + antenna + tuner system into resonance. Dave Casler takes this one step furher. According to him a tuner brings the coax. + antenna + tuner + environment total system into resonance. However. I recognize there are two schools about this. The other persuasion claims that the reflected power is transformed into heat eventually. Regards.
You, as most people, say what SWR is and how it's measured, but do not mention the fact that standing waves that are reflected are not lost power. These waves continue back and forth until they are eventually radiated. This happens millions of times per second.
i made a yagi from tape measures and did not measure anything. just eyeballed it. a signal came out when i put the baofeng on it. its mounted on my roof now and is continually transmitting dead air to the local repeater.
No it is not important to only check VSWR at the radio. You should check it at the antenna with a VNA, yes you should have a radio meter 99% have one in the radio. But checking VSWR after a a long run of coaxial cable is false as the coaxial cable absorbs some of the reflected power as coaxial cable loss. Infact you can add coaxial cable length to soften the reflected power if you don't have a tuner but this will lower your ERP.
A 1.0.1 swr doesn't guarantee that all power is radiated at all , reflected power doesn't go back into the radio to damage it either,terrible info in this video
@@mehmetdemir5655 reflected power adds to the forward power back to antenna and radiated, how much depends on the feedline, loss in the system can make swr low ,reflections by Walt Maxwell explains in great detail what's happening
I will say this... most of the ham videos on the interwebs talk in so much code... that i think they forget there are people who know nothing about the hobby (me) that are trying to learn. So when somebody breaks down definitions (and more importantly, functions and practical applications)... i get jazzed.
So thanks!
Thank you... It's good enough for me to be happy... I'll keep looking for more. I'm bit nerdy.
That was understandable and I appreciate it.
Thank you. I have a lot to learn. Best wishes from NZ.
Thank you a very clear explanation !
OK, so SWR is a measurement of reflected power; so how and why is the power "reflected". Yes, I know it has to do with tuning the antenna so that the impedance matches between the antenna and the radio, but more directly, WHAT reflects the power, and how does tuning the antenna to its resonant length prevent that? Would installing a resistor at the ends of the antenna prevent this reflection?
Your doubt is so profound that I don't even know if most people can imagine how difficult it is to answer "why things are". Children generally want to know the why of things, and not just examples, effects or analogies. And in fact, science still hasn't figured out why a lot of things, actually. The more you understand, the closer you get, but the real reason is still missing. So in the case of reflected power, what I know is that the power comes from the voltage and current of the signal source varying. And then we have current and voltage varying and a transmission medium (the line), and this we call a wave, in this case electromagnetic. And this type of wave has many analogies with other waves, and has much of its behavior explained in Maxwell's electromagnetism equations. He noticed relationships between some existing theories and brought this knowledge together.
In his development there is one that shows the behavior of an electromagnetic wave traveling in a medium and that encounters a change in this medium, such as a fault, a discontinuity, a change of medium (type from air to water, or a coaxial cable to a dipole antenna), or a screen (obstacle). And it turns out that this voltage and current wave, which is also a varying Electric and Magnetic field, when it goes through these types of changes in the environment, each field interacts differently with this change in the environment. But in any of these changes, both the Electric and Magnetic fields interact with this change, and part of the energy that these fields carry interacts with the material of the media and this interaction causes a macro effect, where it appears that the wave has passed forward, but a part of it returns the way it came. This Sometimes the wave that passes ahead passes with its fields unchanged in relation to the phase, other times it does not. The same occurs with the fields of the returning wave. And this occurs whenever this wave goes through these changes in environment. Another important issue is that everything that is at stake here also depends on the frequency that this wave has. If the wave is pure, we can think of just one frequency and that makes it easier to imagine things.
The way in which the Electric field and magnets interact will be different, but the truth is that we do not have signals of this purity. We always have more content in the signal, which means that reality is of a compound complexity, and we need to understand simple things to be able to try to glimpse a little of reality. If you keep asking yourself, why do the Electric and Magnetic fields interact in this way when their transmission medium changes, then you will be going even deeper, arriving at Quantum Field Electrodynamics, a Theory of Physics where almost everything ends up. She tries to explain the interaction of matter, but even she is still unable to explain the truth.
That was very helpful. Thanks!
Best video on the subject I’ve seen!!
Awesome thank you..
Cos my field is in computers, i have some idea, , your wondering, what the hell is an SWR, SWR stands for "Standing Wave Ratio", the transmitting signal travels along the antenna (FORWARD) and refects at the end, returning down the antenna (REFECTED), the forward signal interferes with the reflected signal causing constructive or deconstructive interference, differant lengths create differant phases along the antenna, when a peek meets a peek there is max emission, and when a peek meets a trough there is zero emission, an SWR ratio of 1:1 is perfect constructive interference, where the cycle appears STATIONARY on the antenna, creating a perfect waxing and waning electo-magnetic field, as the electric field collapses, the magnetic field increases and vice versa, , ,Without that load absorbing energy, the energy instead appears as a high voltage or high current somewhere which may not be equipped to handle it, ,
So basically, an ideal 1:1 SWR will produce a low 50ohm resistance match where the antenna does work, the SWR is relatively constant along the feedline, the impedance will vary along the line unless it is perfectly terminated (that is, the SWR is 1.0 : 1). This is an important concept for impedance matching, because with a high SWR, the impedance at the final output transistor load inductor could be mainly higher, or lower than 50 ohms, and produce a high current that damages the finals, , ,
This was great! Does using an antenna tuner mean you gain back the loss watts mentioned?
I too would love to know if an ATU will recover the lost power and the antenna will radiate it, or will the LC circuits in the ATU simply absorb the reflected power and protect the TX finals?
I will keep this simple so I may not be technically correct. 1) An "antenna tuner" does not increase antenna gain. 2) It does make the transmitter think everything is okay so it doesn't reduce TX power to protect the radio. 3) It does help with receiving signals also. This part seems like magic to me because it doesn't fix the resonance of the antenna.
Good explanation, thanks
Howdy.
I would think that a tuner provides a conjugate output impedance to the transmission line + antenna impedance. This, I understand, is the best power transfer setup. So, in my mind, a tuner will recover much of the reflected power and send it back to the antenna to radiate.
A tuner is an impedance trasformer. It transforms 50 ohms purely resistive to the coax. + antenna conjugate impedance.
My thinking is that a tuner does not bring the antenna into resonance. But it brings the coax. + antenna + tuner system into resonance.
Dave Casler takes this one step furher. According to him a tuner brings the coax. + antenna + tuner + environment total system into resonance.
However. I recognize there are two schools about this. The other persuasion claims that the reflected power is transformed into heat eventually.
Regards.
@@eugenepohjola258totally agree
Great video
HOW DID YOU TUNE THE ANTENNAE
How did you tune the antenna
You, as most people, say what SWR is and how it's measured, but do not mention the fact that standing waves that are reflected are not lost power. These waves continue back and forth until they are eventually radiated. This happens millions of times per second.
i made a yagi from tape measures and did not measure anything. just eyeballed it. a signal came out when i put the baofeng on it. its mounted on my roof now and is continually transmitting dead air to the local repeater.
Even ineffective antenna transmit signals.
Tape measure yagis are a fun project.
1980 Caleigh Manor
615 Candida River
646 Sauer Ports
Schaefer Fields
Cassie Overpass
No it is not important to only check VSWR at the radio.
You should check it at the antenna with a VNA, yes you should have a radio meter 99% have one in the radio.
But checking VSWR after a a long run of coaxial cable is false as the coaxial cable absorbs some of the reflected power as coaxial cable loss.
Infact you can add coaxial cable length to soften the reflected power if you don't have a tuner but this will lower your ERP.
Runte Landing
Windler Union
Gilberto Well
02075 Lon Oval
Ahh I see now why many radio operators damage there Nano meter
Batz Mountain
A 1.0.1 swr doesn't guarantee that all power is radiated at all , reflected power doesn't go back into the radio to damage it either,terrible info in this video
what is the truth?
@@mehmetdemir5655 reflected power adds to the forward power back to antenna and radiated, how much depends on the feedline, loss in the system can make swr low ,reflections by Walt Maxwell explains in great detail what's happening
@@paulm0hpd319 Oh, thank you for your reply
@@mehmetdemir5655 reflections 3 is a free download
@paulm0hpd319 absolutely correct 👏
great
Next time point to where you are explaining, for those who are learning these calculations.