Thanks for viewing my channel. I'm a retired electrical engineer with a background in analog and RF design. I love using Microsoft Excel for circuit design calculators. I want to pass along my experience with these videos. Please like, subscribe, and click the notification bell so you don't miss any content.
I am a big fan of your videos. I love the fact that you mathematically derive your explanations. I have noticed that there is a "dearth" of microwave theory textbooks, or lab manuals for that matter, that set forth the underlying mathematics of simple RF network analysis equations - simple transmission line problems for complex series and parallel networks. Could you recommend a couple of microwave theory textbooks (or lab manuals) that derive their equations and support their equations with "enumerated" examples (I am really looking for "textbooks" with enumerated solutions)?
Thanks so much. Unfortunately I have not seen a RF book that does what you are talking about, which is a shame. In my observation, it looks like RF and microwave text book are regurgitations of previous ones, especially with waveguide. It’s a bunch of vector calculus with no real world examples. I wish I could be more help.
Very complete video! Do you know if there is a way to demonstrate or find the matrix of the rotator from the circuit with the operational? I tried but it didn't work out. I also didn't find any books that talk about the subject in detail or that give demonstrations, most of them just spit out the equations without showing where they come from.
I like your channel very much! As I understand, if you replace the delta connection Z3, 4, 5 by a star connection you could eliminate one part pointing to negative input of the opamp.
If you had asked me before watching this, I would have assumed that breakdown voltage increased with less air. I find it very counter intuitive that less air means less power. I'm guessing that it starts to curve back up once you get near vacuum, since there's nothing to ionize?
One of the best videos on this and much more understandable than what I have seen in textbooks. Thank you! I know that using a cap in parallel with the feedback resistor is common with inverting amplifier circuits, but I have also seen it in non-inverting amplifier circuits. Of course at higher frequencies that cap will only reduce the closed loop gain to unity, until some other pole reduces the gain further at higher frequencies. So does the cap in parallel with the feedback resistor in non-inverting configurations help with closed loop stability?
Yes indeed. For stability, you only look the feedback network. While the overall circuit is a low pass filter, within the feedback loop is a series capacitor which results in a stabilizing zero. Great question. I should have included that in the video.
Awesome explanation... and the visuals were incredibly helpful. The use of motion From diagram to diagram was really A terrific support to help understanding the concepts.
Hi. Thanks for posting this, really useful. I am a lefty guitarist who struggles to source reverse logarithmic pots, and after watching your video I was wondering if I could convert a standard 500k linear potentiometer to logarithmic by fitting a 75k resistor to it? I'm thinking the resistor would be connected to the centre lug and the outer lug that is going to ground? Any thoughts? Thanks 👍
Yes indeed. Just know that the added load resistance will damp the pickup’s resonance (usually less highs). Let us know how it works out for you. Thanks for the comment.
Isn't it more proper to say "Voltage between opamp inputs is zero (virtual short) if the opamp has an infinite open loop gain AND is in a negative feedback configuration." ???
Nothing “cancels out” because that would violate the second law of thermodynamics. Energy cannot be created or destroyed. What happens when you have two equal but opposite current flows 180 degrees out of phase is it creates a bucking coil effect, where by the two transverse waves collapse (not cancel) to form a single longitudinal wave, which registers as a voltage potential. Essentially all capacitors are standing longitudinal waveguides, where in the simplest example you have two parallel opposing metal plates separated by a distance of air or some other dielectric. When current flows into a capacitor, the current, which is TEM or transverse electromagnetic, starts to bounce back and forth between the two plates until all the current eventually phase-collapses into a single longitudinal standing wave in the Aether/ZPE field, which again registers as a voltage potential on an oscilloscope. The energy does not ‘cancel out’ but is transformed. And when a capacitor is discharged, the reverse happens, where by the longitudinal standing wave is converted back into transverse-electromagnetic current flow. It’s a ying/yang effect where energy is constantly being transformed from TEM to LMD and back again. LMD stands for longitudinal dielectric mode. The dielectric field in matter is what determines its conductivity and permittivity. And in a transmission line or coax cable you have both happening at the same time, as some current is transformed from transverse-electromagnetic into longitudinal dielectric, which is why all cables have capacitance, resistance and generate heat losses. It all comes down to the wave effects.
So what does that mean for waveguides in space, it looks like its down to a few watts would that be right? or is voltage breakdown in space much higher as there is no air
The next regime of microwave mayhem for space applications is known as multipaction or multipactor. It is a resonance breakdown phenomena requiring both a vacuum (no air) and radiation (free electrons) environment.
@@oldhackee3915 Your plot is fine. There is a lot of interesting Physics summarized in a Paschen Diagram, especially that the x-axis is product fo frequency*dimension.
Maybe if we used sulfur hexafluoride gas SF6 as a wave guide quench gas, we could push more power. I guess we would have to shield the outside as well as the inside.
Microwaves _are_ analog! They're just in one of the gaps in our analog ranges of perception. Too fast to hear; too slow to see. As far as I know, Old Hack hasn't uploaded anything that _isn't_ about analog, and I love him for that. None of that digital rubbish on this channel!
This was fascinating, thank you. I'm 32 and I've spent a lot of time exploring the various long-lines towers in my area and I've never even remotely understood how waveguides worked until now. I just assumed they were like a fiber-optic pipe for radio waves, hap hazard bouncing along like a river of energy in there. As a machinist by trade, I find it particularly fascinating the relationship of the physical dimensions and tolerances to the frequencies and efficiency of the system. Can it be dangerous to send the wrong frequency down an incorrectly sized waveguide to ending up with current on the exterior surfaces of the waveguide?
Thank you for the video, it's a nice, concise explanation. One thing to add: the fact that the length of the choke is not constant across the broad wall helps make the match better over a broad range of frequencies. If the geometry was made exactly lambda/4 over the width of the broad wall, we'd get a good VSWR at only one frequency. Also, beyond about 40 GHz, it's common to see the UG/387 style flanges that use alignment pins to ensure that the tiny openings stay lined up. I have not come across choke flanges below WR-28 (Ka-band). I suppose the grooves become too difficult to machine.
excellent, I know nothing about wave guides but that helps no end. I do wonder how the ripples in the flexible concertina walls don't cause all sort of reflections, are they at 1/4 wavelength apart or something?
I don't have any experience with the flexible elliptical waveguide. I surmise that it only adds length, otherwise it would not be very useful. Thanks for the comment.
I've built the circuit shown at the 5 minute mark to condition a signal from a piezo disc. I'm attempting to collect chest expansion (from breathing) and heart beats when the piezo is laid upon. I was wondering if you could comment on the 2 capacitors stimming from the V_s? How to size them and why are there two? Thanks in advance!
Thanks for the comment. It depends on how noisy your supply is. If the power comes from a rectified AC line and has some power line ripple in it, it's typical to have a large value capacitor like a 10-47µF electrolytic or tantalum type. Since most large capacitor values will have a significant Effective Series Resistance (ESR), it's necessary to put a smaller value ceramic or mylar type in parallel, having a low ESR to help shunt the higher frequency noise that may be on the supply line.
My experience with waveguides goes back to the mid to late 60's when I operated and maintained tropospheric scatter equipment. Never understood the theory but I like your vid. Thanks.
Thanks so much for this. I rarely comment on videos before watching the whole thing but I'm going to go ahead and do so here. Part of my current job has me working in international standards committees and with national, regional, and international regulatory bodies to help develop new standards for my industry and new regulatory rules for the operation of equipment in various frequency bands. I had seeing unexplained numerical constants in formulae or rules and where possible have pushed for anything I've worked on to at least show the derivation of the constant in the document so that newcomers will understand how the constant came about and what it contains. The other is getting people on board with the SI and carrying units through in formulas documents. This allows folks to follow along and get used to doing some unit analysis long the way. If when working through the problem on their own they come up with meters per second when they were looking for watts per hertz they know a mistake was made along the way.
Thanks for this. Have been working in the satcom industry for almost 50 years and have worked with my share of waveguide. Interestingly I think usage has declined a fair bit in recent years as there's an increased shift to smaller solid state power amplifiers that can be mounted closer to antenna feeds. Used to be commonplace to have HPA (high power amplifier) rooms with waveguide plumbed all over the place at gateway earth stations, but now not so much. For user terminals everything is pretty much feed mounted and you don't see any external waveguide.
Wow that’s a lot of experience. Yes that’s a trend for sure. UHF television transmitters are good examples of use, but now with everything streaming, I wonder how long terrestrial broadcast will last. Thanks for the comments.
