Small magnetic tunable filter for 6G and beyond

[Jan Panteltje]

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.

[Jeroen Belleman]

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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

[john larkin]

On Mon, 27 May 2024 09:56:53 +0200, Jeroen Belleman

Post by Jeroen Belleman

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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 filters and oscillators have been around for ages. It seems to me
that tuning them with a magnetic field is messy.

[Phil Hobbs]

Post by Jeroen Belleman

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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

[Phil Hobbs]

Post by Phil Hobbs

Post by Jeroen Belleman

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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

offset

is a good 30 dB better than any SDR-style analyzer.

Post by Phil Hobbs
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

[john larkin]

On Mon, 27 May 2024 12:58:08 -0000 (UTC), Phil Hobbs

Post by Jeroen Belleman

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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?

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.

Qs are low too.

Does your HP have a big ovenized mu-metal box inside?

[Phil Hobbs]

Post by john larkin
On Mon, 27 May 2024 12:58:08 -0000 (UTC), Phil Hobbs

Post by Jeroen Belleman

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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.

Post by john larkin
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.

Cheers

Phil Hobbs

Post by john larkin
Qs are low too.
Does your HP have a big ovenized mu-metal box inside?

[john larkin]

On Mon, 27 May 2024 22:37:31 -0000 (UTC), Phil Hobbs

Post by Phil Hobbs

Post by john larkin
On Mon, 27 May 2024 12:58:08 -0000 (UTC), Phil Hobbs

Post by Jeroen Belleman

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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.

Post by john larkin
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.
Cheers
Phil Hobbs

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.

[Phil Hobbs]

Post by john larkin
On Mon, 27 May 2024 22:37:31 -0000 (UTC), Phil Hobbs

Post by Phil Hobbs

Post by john larkin
On Mon, 27 May 2024 12:58:08 -0000 (UTC), Phil Hobbs

Post by Jeroen Belleman

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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.

Post by john larkin
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

[Bill Sloman]

Post by john larkin
On Mon, 27 May 2024 12:58:08 -0000 (UTC), Phil Hobbs

Post by Phil Hobbs

Post by Jeroen Belleman

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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?
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.
Qs are low too.
Does your HP have a big ovenized mu-metal box inside?

Electron microscopes and magnetic deflection mass spectrometers regulate
magnetic fields pretty precisely - the Cambridge Instruments EBMF 10.5
that I worked on used two othogonal magnetic fields to put the electron
beam precisely were it was wanted to 15-bit precision at 10MHz.

I got dragged in when the Johnson noise in the existing scanning
amplifiers started making the lines it drew look a bit blobby, which I
fixed by taking the low noise FETs out of the front end - we didn't need
the low input impedance they offered - and relying on the low noise
transistors with which they had been cascoded.

Admittedly we only had the 10MHz step rate inside a 12-bit sub-field,
and stepped between those sub-fields involved 1msec of settling time -
the 18-bit DAC that looked after that was bit slow.

It's certainly not easy to regulate magnetic fields to parts per
million, but it can be done.

The big mass spectrometer - that I worked on for a couple of months at
one point - used a Hall plate to regulate its magnetic field to that
sort of precision.

I had a potentially patentable idea to make it work a bit better, but
when we looked into it the idea had been spelled out elsewhere though
the engineers who had put the machine together hadn't heard about it.

[Joe Gwinn]

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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.

As with many breathless announcements of breakthroughs, this may not
fare well in reality, for all the reasons mentioned up thread. But
anyway, here is the full announcement:

.<https://blog.seas.upenn.edu/to-6g-and-beyond-penn-engineers-unlock-the-next-generation-of-wireless-communications/>

The item about LightSquared is amusingly off-mark: The problem with
LightSquared was that their proposed ground-based transmissions were
far too strong, and threatened to overwhelm existing GPS receivers, in
particular those in safety-of-flight involved GPS receivers. Inventing
a fancy new filter won't help any more than boring old filter
technologies, as it's the GPS receivers would need to be updated and
recertified, which is a very big deal.

I haven't looked, but I bet there is an arXive paper on the yig filter
details.

Joe Gwinn

[john larkin]

Post by Joe Gwinn

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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.

As with many breathless announcements of breakthroughs, this may not
fare well in reality, for all the reasons mentioned up thread. But
.<https://blog.seas.upenn.edu/to-6g-and-beyond-penn-engineers-unlock-the-next-generation-of-wireless-communications/>
The item about LightSquared is amusingly off-mark: The problem with
LightSquared was that their proposed ground-based transmissions were
far too strong, and threatened to overwhelm existing GPS receivers, in
particular those in safety-of-flight involved GPS receivers. Inventing
a fancy new filter won't help any more than boring old filter
technologies, as it's the GPS receivers would need to be updated and
recertified, which is a very big deal.
I haven't looked, but I bet there is an arXive paper on the yig filter
details.
Joe Gwinn

Does satellite nevigation need a low-Q tunable bandpass filter? There
are great SAW-type resonators around with better filtering, no magnets
required.

[Gerhard Hoffmann]

Post by john larkin
Does satellite nevigation need a low-Q tunable bandpass filter? There
are great SAW-type resonators around with better filtering, no magnets
required.

The one thing one would not want in a GPS-like receiver is a
high-Q antenna filter with its high and unstable group delay.

And there are no SAW filters you could really buy above a FEW
GHz, apart from some WLAN frequencies where nobody cares if
it works today or not. Just checked DigiKey again.

At 10 GHz, I'm limited to copper pipe end caps for ham
radio use and DiElectric resonators for our medical electron
spin stuff. Both not really tunable.

Gerhard.

[Bill Sloman]

Post by john larkin

Post by Joe Gwinn

Post by Jan Panteltje
https://www.sciencedaily.com/releases/2024/05/240524114938.htm
University of Pennsylvania School of Engineering and Applied Science
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.
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.

As with many breathless announcements of breakthroughs, this may not
fare well in reality, for all the reasons mentioned up thread. But
.<https://blog.seas.upenn.edu/to-6g-and-beyond-penn-engineers-unlock-the-next-generation-of-wireless-communications/>
The item about LightSquared is amusingly off-mark: The problem with
LightSquared was that their proposed ground-based transmissions were
far too strong, and threatened to overwhelm existing GPS receivers, in
particular those in safety-of-flight involved GPS receivers. Inventing
a fancy new filter won't help any more than boring old filter
technologies, as it's the GPS receivers would need to be updated and
recertified, which is a very big deal.
I haven't looked, but I bet there is an arXive paper on the yig filter
details.
Joe Gwinn

Does satellite nevigation need a low-Q tunable bandpass filter? There
are great SAW-type resonators around with better filtering, no magnets
required.

But they aren't tunable.