Path: ...!npeer.as286.net!npeer-ng0.as286.net!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Phil Hobbs Newsgroups: sci.electronics.design Subject: Re: Small magnetic tunable filter for 6G and beyond Date: Mon, 27 May 2024 20:54:59 -0400 Organization: A noiseless patient Spider Lines: 97 Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Tue, 28 May 2024 02:54:59 +0200 (CEST) Injection-Info: dont-email.me; posting-host="91b844ad3d80271cf05063f835af82da"; logging-data="307372"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX199TtuR60bniJwLcUvU5cRM" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.0 Cancel-Lock: sha1:NGYa2y8m3rv8MDGYRS/bPfGYeNs= In-Reply-To: Bytes: 5294 On 2024-05-27 19:07, john larkin wrote: > On Mon, 27 May 2024 22:37:31 -0000 (UTC), Phil Hobbs > wrote: > >> john larkin wrote: >>> On Mon, 27 May 2024 12:58:08 -0000 (UTC), Phil Hobbs >>> wrote: >>> >>>> Jeroen Belleman wrote: >>>>> On 5/27/24 07:08, Jan Panteltje wrote: >>>>>> To 6G and beyond: Engineers unlock the next generation of wireless communications: >>>>>> https://www.sciencedaily.com/releases/2024/05/240524114938.htm >>>>>> Source: >>>>>> University of Pennsylvania School of Engineering and Applied Science >>>>>> Summary: >>>>>> Engineers have developed a new tool that could unlock 6G and the next >>>>>> generation of wireless networks: an adjustable filter that can >>>>>> successfully prevent interference in high-frequency bands of the >>>>>> electromagnetic spectrum. >>>>>> partial quote: >>>>>> What makes the filter adjustable is a unique material, "yttrium iron garnet" (YIG), >>>>>> a blend of yttrium, a rare earth metal, along with iron and oxygen. >>>>>> "What's special about YIG is that it propagates a magnetic spin wave," says Olsson, >>>>>> referring to the type of wave created in magnetic materials when >>>>>> electrons spin in a synchronized fashion. >>>>>> When exposed to a magnetic field, the magnetic spin wave generated by >>>>>> YIG changes frequency. >>>>>> "By adjusting the magnetic field," says Xingyu Du, a doctoral student in >>>>>> Olsson's lab and the first author of the paper, >>>>>> "the YIG filter achieves continuous frequency tuning across an extremely >>>>>> broad frequency band." >>>>>> As a result, the new filter can be tuned to any frequency between 3.4 GHz and 11.1 GHz, >>>>>> which covers much of the new territory the FCC has opened up in the FR3 band. >>>>>> >>>>> >>>>> YIG filter and resonators have always been a bit exotic. Maybe this >>>>> will make them common-place. And more compact, hopefully! The YIG >>>>> was tiny, sure, but the magnet wasn't. >>>>> >>>>> Jeroen Belleman >>>>> >>>> >>>> YIG-tuned VFOs are the champs for low close-in phase noise. My HP 8566B?s >>>> noise floor at 1kHz is a good 30 dB better than any SDR-style analyzer. >>>> >>>> If they manage to get them down to Digikey-level practicality without >>>> screwing that up, it would be huge. >>>> >>>> I wonder if you could use a mag amp sort of structure, with a rare earth >>>> magnet biasing some cleverly designed bits of saturable ferrite, plus some >>>> small coils changing the effective gap in the magnetic circuit. >>>> >>>> Fun to think about. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> How can one keep a magnetic field stable to parts per billion? >> >> Normally unnecessary for a YTO, I think. >> >>> Seems like ambient 60 Hz fields and temperature changes and tiny >>> noises in the coil current would dominate. It's hard to regulate a >>> current to parts per million. >>> >> >> A well-degenerated BJT with a 2- or 3-pole lowpass on the base makes a deep >> sub-Poissonian current source. One of our laser drivers has a noise floor >> below -190 dBc/Hz at 400 mA, about 24 dB below shot noise. >> >> You do have to handle the low baseband somehow, of course. For the laser >> driver it’s an op amp and voltage reference, and for the YTO it’s a PLL. > > Is the yig phase-locked to an XO? I guess that would make a nice > jump-tunable first-mixer oscillator. Something else would have to > sweep the IF. > The 8566B has a complicated frequency plan that I've never gone into in full detail. Sure works though! Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com