[HN Gopher] Novel microwave isolator points the way to new radio...
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Novel microwave isolator points the way to new radio cameras,
quantum computers
Author : wglb
Score : 58 points
Date : 2023-07-05 22:18 UTC (2 days ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| yummypaint wrote:
| _Abstract:We propose a nonreciprocal microwave isolator realized
| using an electrical circuit with two frequency mixers. A phase
| shift between the mixers at the same frequency as the local
| oscillator (LO) frequency is $\pi /4 + m\pi /2$ , and the powers
| of LO applied to each mixer have a phase difference of $\pi /4+
| n\pi /2$ (where $n$ and $m$ are the arbitrary integers). The up-
| converted signals in the upper and lower sidebands at the first
| mixer are combined at the subsequent mixer, even if they have
| phase differences. Because each sideband is in-phase for one
| direction and out-of-phase for the other direction, the circuit
| principally functions as an isolator with broadband from near dc
| to LO frequency. An isolator using commercially available
| microwave components successfully demonstrated more than 17 dB of
| isolation across the 0.01-1.50-GHz band at an LO frequency of
| 2.30 GHz. An on-chip broadband isolator with positive gain can be
| realized using superconductor-insulator-superconductor mixers._
| superkuh wrote:
| 17 dB is not bad for an isolator, but it's not good either. But
| this kind of just begs the question by using frequency mixers
| as the non-reciprocal element because frequency mixers are such
| lower power devices. I guess this helps for really lower power
| science stuff, but not so much communications.
|
| Still, very cool! The only other non-magnetic non-reciprocal RF
| elements I can think of used angular-momentum bias.
| phendrenad2 wrote:
| What does this mean in simple terms?
| lightedman wrote:
| Boiled down to the simplest terms? Microwave diode.
| _Microft wrote:
| That was might first thought as well but "diode" might make
| people think about polarity.
|
| I would rather describe it as _unidirectional valve for
| microwaves_ instead.
| hammock wrote:
| Imagine you have a special device that can control the flow
| of microwaves. This device is like a gate that only lets the
| waves pass through in one direction and blocks them from
| going the other way.
|
| To make this device, we use a special circuit with two parts.
| These parts are like mixers that combine different waves
| together. When we put the waves into these mixers, they
| change a little bit and become different from how they were
| before.
|
| The waves that come out of the mixers are then combined
| together again. Even if they changed a little bit, we can
| still put them together. It's like putting puzzle pieces
| together even if they don't match perfectly.
|
| The cool thing is that when the waves go through this device,
| they behave differently depending on which direction they're
| going. It's like a one-way street. If the waves go in one
| direction, they can pass through the device without any
| problems. But if they try to go in the other direction, they
| get blocked and can't pass through.
|
| The device that was described in the abstract was made using
| parts that are easily available. It worked really well and
| blocked the waves from going in the unwanted direction,
| giving us more than 17 times less of those waves.
|
| The abstract also mentions the possibility of making an even
| better device using a different kind of part that can make
| the waves stronger. It's like giving the waves a little
| boost. This new device could be made very small and fit on a
| tiny chip.
|
| So, in simple terms, the abstract is talking about a device
| that can control the flow of microwaves and only let them go
| in one direction
| abecedarius wrote:
| So the basic problem to overcome is, microwaves are a kind
| of light, and if I can see you, you can see me, no matter
| what ordinary fancy optics are in between. If a light ray
| gets from you to me, then the reverse path is physically
| exactly the same as time-reversing the original light ray
| (and time reversal is a symmetry of electromagnetism).
|
| I read the above explanation and I still don't get where it
| overcomes reciprocity. (Didn't try to read the paper
| itself.) Can you point to where the asymmetry is
| introduced? Or how I'm thinking about this all wrong?
| hammock wrote:
| The mixers in the device are designed to combine
| different frequencies of waves together. By carefully
| adjusting the phase shift between the mixers and the
| powers of the local oscillator (LO) applied to each
| mixer, a specific phase relationship is created for the
| up-converted signals (upper and lower sidebands) produced
| by the mixers.
|
| When these signals are combined again in a subsequent
| mixer, they interact in a way that results in different
| phase relationships for waves traveling in different
| directions. This means that the waves are in-phase (in
| sync) for one direction but out-of-phase (out of sync)
| for the opposite direction.
|
| This phase relationship difference causes an asymmetry in
| how the waves propagate through the device. Waves
| traveling in the desired direction experience
| constructive interference, meaning they reinforce each
| other and can pass through the device. On the other hand,
| waves traveling in the opposite direction experience
| destructive interference, meaning they cancel each other
| out and are blocked from passing through.
| _a_a_a_ wrote:
| is this your summary or chatGPT? Serious question, no
| judgment
| Arrath wrote:
| I can't say I've often seen GPT use phrases like "the
| cool thing about this.."
| nomel wrote:
| That's trivial, by asking it to respond with a certain
| "personality". Something like "respond as a space cowboy
| from Silicon Valley, who was an elementary school science
| teacher."
| jaycroft wrote:
| A 17dB reduction in power is not 17 times less! It is a
| reduction by a factor of 10^(17/10) or about 50 times.
| le-mark wrote:
| Tesla valve for microwaves then?
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(page generated 2023-07-07 23:02 UTC)