Last fall I picked up "Receiving Antennas" -- this should work nicely using Analog's low noise AD8067. The only concerning item is the "guard ring" for the non-inverting application. I threaded a 1 mil trace through the pins of an SOT23-5 device:
Attachments
Radiation resistance will be small and vary with frequency. Ferrite rods make poor antennas, but they are small and directional and at LW and MW they are good enough because signal levels and noise levels are high. They can also work at the low frequency end of the HF spectrum.
How will you be coupling to the antenna? There are various methods:
1. coupling link to medium impedance input
2. direct connection of parallel resonant circuit to very high impedance input
3. direct connection of series resonant circuit to very low impedance input (e.g. virtual ground)
How will you be coupling to the antenna? There are various methods:
1. coupling link to medium impedance input
2. direct connection of parallel resonant circuit to very high impedance input
3. direct connection of series resonant circuit to very low impedance input (e.g. virtual ground)
Several articles written by Chris Trask, but this on shows varactor tuning with a balanced/balanced network: https://pdfs.semanticscholar.org/bd27/2cd6f2f6bbda3ec3c3812a2e622d7b59c10f.pdf
My motivation -- I want to listen to baseball games broadcast live -- owing to contract issues these aren't available unless you purchase a very expensive package. Also thinking of doing some work on the new VLF ham radio bands.
My motivation -- I want to listen to baseball games broadcast live -- owing to contract issues these aren't available unless you purchase a very expensive package. Also thinking of doing some work on the new VLF ham radio bands.
well, it's an experiment. i don't think you can really entirely trade mu for "cross sectional area" in the real world.
stateside, there is still quite a bit of a.m. broadcast with a lot of local content (but only ONE a.m. station which has a classical format!)
Radio Station Formats
Amplifier AND varactor tuning in a remote location presents some challenges -- MV109 varactor tunes 20 to 400 pF with 1 to 9 V bias, amplifier probably reconfigured for single supply. I would like to do this with the center coax conductor "hot". Suggestions welcome.
Since the AD8067 can be run 5 to 24V, just a simple resistive divider after the amplifier and run the center coax with a basic programmable supply?
Are there any surface mount varactors with the magnitude and range of these old Motorola units?
Since the AD8067 can be run 5 to 24V, just a simple resistive divider after the amplifier and run the center coax with a basic programmable supply?
Are there any surface mount varactors with the magnitude and range of these old Motorola units?
Another paper by Trask:
"Active Ferrite Rod Antenna with Remote Tuning" http://home.earthlink.net/~christrask/Active Ferrite Rod Antenna.pdf
Some sources:
Rods Archives - Fair Rite
Ferrite Rods - Palomar Engineers(R)
"Active Ferrite Rod Antenna with Remote Tuning" http://home.earthlink.net/~christrask/Active Ferrite Rod Antenna.pdf
Some sources:
Rods Archives - Fair Rite
Ferrite Rods - Palomar Engineers(R)
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