Delaying/shifting the start of a square wave inverter

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Creating a two-phase square wave setup at multi-gigahertz frequencies involves configuring the second wave to start at 90 degrees relative to the first. Options discussed include using a phase-locked loop (PLL) with a quadrature phase detector or employing a delay line that is a quarter wavelength long for fixed frequencies. The feasibility of achieving a perfect square wave at these frequencies is questioned due to potential inductance effects, which may result in a signal that resembles a sine wave instead. Participants emphasize the importance of understanding the specific frequency range and characteristics of the desired output. Ultimately, the discussion highlights the complexities involved in generating and manipulating high-frequency square waves.
  • #31
I am almost there. I just need a frequency generator or inverter of some sort, with a frequency of no lower than 4GHz, hopefully one that won't break the bank either.

If it is fixed frequency, just use a delay line; a length of wire, circuit board trace, or waveguide that is 1/4λ long.
As for a phase shifter, I will use the delay line method, thanks.
 
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  • #32
CCatalyst said:
Summary:: Or can a square wave function be phase-shifted at all?

I am trying to create a two phase type setup where I have a square wave in the multi-gigahertz frequency. However, I want the second wave to start once the first one reaches 90 degrees. How can the circuit be configured to do this? Will a phase shifter do or can a square wave be phase shifted at all even at this high frequency? And if now what do I need to do?
You cannot create a square wave at microwave frequencies.

It is not possible.

But you can make quadrature sine waves with some harmonics. You are not able to control the phase and amplitude of those harmonics found in a square wave due to the geometric sensitivity of standing waves and loss tangents of dielectric.

try making it at 100 MHz with over 10 harmonics after you get 1kHz quadrature to work.
 
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  • #33
You cannot create a square wave at microwave frequencies.

It is not possible.

But you can make quadrature sine waves with some harmonics. You are not able to control the phase and amplitude of those harmonics found in a square wave due to the geometric sensitivity of standing waves and loss tangents of dielectric.

try making it at 100 MHz with over 10 harmonics after you get 1kHz quadrature to work.
It no longer has to be a square wave.
 
  • #34
CCatalyst said:
As for a phase shifter, I will use the delay line method, thanks.
I understand that you find the idea of a length of delay line attractive; it sounds straightforward. However, you would need a circuit analyser to adjust for quadrature phase. Using a directional coupler gives you 'good' quadrature over a wide frequency range. I don't know what sort of hardware you envisage but, at a few GHz, it's really not trivial, unless you are already fairly expert in the field. You need to plan the circuit systems very early on. If you plan to use printed circuit techniques (micro strip) then couplers are easy to achieve (DIY) - much more so than getting the right line lengths. All you have to do is keep the lengths equal - coax or whatever.
 
  • #35
I understand that you find the idea of a length of delay line attractive; it sounds straightforward. However, you would need a circuit analyser to adjust for quadrature phase. Using a directional coupler gives you 'good' quadrature over a wide frequency range. I don't know what sort of hardware you envisage but, at a few GHz, it's really not trivial, unless you are already fairly expert in the field. You need to plan the circuit systems very early on. If you plan to use printed circuit techniques (micro strip) then couplers are easy to achieve (DIY) - much more so than getting the right line lengths. All you have to do is keep the lengths equal - coax or whatever.
Well what do you recommend? The delay wire or the quadrature method? Also I am going to use the 1.575GHz patch-type antenna for this. I am going to use them instead of inductors because not only will iron cores not work for such high frequencies (reasons why were discussed earlier) but it would just not be powerful enough. I need both a small enough right and left hand polarization antenna that does this.

By the way, how do I POWER RF systems? Is there anything that con hold a battery and use it to run an RF system? And is it adjustable?

Oh, and to those now joining, I NO LONGER need a square wave for this.
 
  • #36
CCatalyst said:
By the way, how do I POWER RF systems? Is there anything that con hold a battery and use it to run an RF system? And is it adjustable?
Please take no offense but do you really understand what you are trying to do?

It's like asking "how do I drink a beer bottle" "do I hold it upside down and let the liquid flow into my mouth, can I adjust the flow of beer? "

I would really suggest explaining what you are doing fully and what you aim to do, that is the only way you will get a meaningful answer and maybe even learn something. In case you think you have a novel idea and are reluctant to share , I would suggest that cannot be the case given you ask such basic questions that show your lack of understanding in the field.
 
  • #37
CCatalyst said:
It no longer has to be a square wave.
As I understand it, you want a quadrature shifted wave so you can make a circulating field in a cavity at a frequency greater than 4 GHz.

You originally considered crossed coils with "iron" to make stronger fields, and RC phase shifters, but have now switched to capacitor plates with delay lines. Now you are suggesting a 1.6 GHz antenna will be operated at above 4 GHz.

It now looks like you need a cavity in a waveguide system that will support a circularly polarised wave. Then you can dispose of the quadrature shifter and the associated antenna losses. There can be little point in this thread if you will not identify what will go in the cavity and why that something will magically behave differently.

You have still not specified the power required to drive the magic.
 
  • #38
Baluncore said:
You have still not specified the power required to drive the magic.
That's only one of the things that have not actually been addressed by the OP. I think he has no idea of what he's actually proposing.

I foresee a cardboard box in the OP's shed / basement, full of (expensive) microwave bits that have never actually been connected up. This is not the way to approach a serious research project but suppliers are always happy to sell experimenters stuff that won't be of any use to them.
 
  • #39
sophiecentaur said:
I foresee a cardboard box in the OP's shed / basement, full of (expensive) microwave bits that have never actually been connected up.
I really don't think this confirmation of the Dunning-Kruger effect will get as far as the cardboard box. Secrecy is essential in that it prevents a final design, so no experiment is possible. Any attempt to actually experiment will rapidly demonstrate failure, and so destroy the delusion. It must forever remain a dream.
 
  • #40
CCatalyst said:
Also I am going to use the 1.575GHz patch-type antenna for this.
You do know what that band is used for, right? What do you think will happen when you start throwing out sloppy versions of your signal in that band?

This thread has gone on long enough. We don't support newbies trying to design GHz transmitting circuits for secret applications. Thread is closed.

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https://aerospace.csis.org/what-the-fcc-ligado-approval-means-for-u-s-military-systems/
 

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