[HN Gopher] An adjustable filter that can prevent interference i...
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An adjustable filter that can prevent interference in the range 600
MHz to 6 GHz
Author : giuliomagnifico
Score : 47 points
Date : 2024-05-27 16:06 UTC (6 hours ago)
(HTM) web link (blog.seas.upenn.edu)
(TXT) w3m dump (blog.seas.upenn.edu)
| lrasinen wrote:
| Not quite: "As a result, the new filter can be tuned to any
| frequency between 3.4 GHz and 11.1 GHz..."
|
| The 600 MHz to 6 GHz referred to currently used communication
| frequencies.
| giuliomagnifico wrote:
| I was referring to the interferences range where the filter can
| work, not where it can be tuned. If I correct understood.
| nestes wrote:
| The 600-6GHz range is a rough approximation for some of the
| most used bands in telecommunications, e.g. Wi-Fi and 5G NR
| FR1. It's worth noting that the article explicitly mentions
| that this filter will be useful for FR3, which is "7 GHz to
| 24 GHz". They do not claim full 600 MHz-6 GHz operation, and
| as the previous poster noted, the filter was demonstrated
| from 3.4-11.1 GHz.
|
| More critically: you want to be very very careful about
| trying to extrapolate this filter down to lower frequencies.
| We're dealing with "weird physics" here. I am not an expert
| on spin-wave devices by any means, but a guy in my lab during
| grad school was working with them, so I do know that the
| resonant frequencies of the spin-waves are a function of the
| magnetic bias and the material. The researchers here are
| tuning the filter by tuning the magnetic bias. Someone more
| knowledgeable can correct me, but I believe YIG would have
| trouble propagating spin-waves down at 600 MHz, and so this
| kind of filter would not be practical.
| FuckButtons wrote:
| I wonder if you could use this to overcome electronic warfare
| jamming of gps.
| gmrple wrote:
| No, this is about preventing unwanted jamming/interference by a
| transmitter on frequencies it isn't intending or needing to
| transmit on as part of the design phase of a product.
| Overcoming intentional jamming is an entirely different
| ballgame.
| instagib wrote:
| There's a lot of strategies for this but a basic one is using
| direction find on the jammer. then electronically or manually
| moving antenna nulls (bad spots of a directional antenna) to
| face the jammer(s) which would then increase the gain for
| directed non-jammer areas.
|
| GPS is a very low amplitude signal that can easily be jammed.
| Dropping WP (white phosphorus) or a missile on the suspected
| jammer would be a better bet.
| willcipriano wrote:
| > Dropping WP (white phosphorus)
|
| "Your GPS jammer prevented my war crime so here's a bigger
| war crime." - The good guys
| lnsru wrote:
| It might be cool, but I wasn't able to find price comparison to
| existing technologies. The modules containing dozens of specified
| filters are dirt cheap. Since band frequencies for 5G are known
| no fine tuning needed. Also no fab wants exotic materials and a
| new process.
| RachelF wrote:
| Yes, this article is marketing. They've just made a prototype
| smaller filter.
|
| YIG filters have been around for decades. They are electrically
| tunable. However, they are slow to change frequency and can
| have an odd phase response.
| mikewarot wrote:
| The main innovation here seems to be the elimination of a bias
| electromagnet that consumes a constant current to generate a
| desired amount of magnetic flux.
|
| These apparently can consume 250 milliamp, if my quick Google is
| right.
|
| Here's a paper[1] that might be how they are doing it.
|
| [1] https://ieeexplore.ieee.org/document/7529113
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