7 ms·

There is a very small slice that amateur radio gets in this band, in theory it would be nice to have a bigger slice, but honestly, building antennas for this ba

by aeonik 3mo ago

There is a very small slice that amateur radio gets in this band, in theory it would be nice to have a bigger slice, but honestly, building antennas for this band to transmit anything worthwhile would be pretty hard. My 7 Mhz antenna (HF, 40m band) is 67 feet long, and goes across by whole house. The smallest antenna you could get away with for LF would be hundreds to thousands of feet long. You might be able to go smaller if you enjoy suffering. Though, there are some pretty creative antenna designs that defy logic.

microgpt 3mo ago
Does stapling it to your neighbours' fence lines and painting it like the wood count as creative? I wonder if you can couple to your local distribution grid, and not get arrested.
- aeonik 3mo ago
  I just string the antenna across my attic. Coupling into my power upstairs is a bit of a problem sometimes though. Pirating power is something I've heard that happens, but I looked it up, and couldn't find an actual cited example of someone doing it via induction. Plenty of people doing it via extension cords and device tampering though.
  - ErroneousBosh 3mo ago
    > Coupling into my power upstairs is a bit of a problem sometimes though. I haven't worked with my end-fed on 40m for a couple of years. We've recently all had our crappy old aluminium-cored BT lines replaced with shiny new fibre though, so this time I am unlikely to lift the coveted Worked All DSLAMs trophy ;-)
  - microgpt 3mo ago
    I meant feeding RF back into the power grid to use it as your very large antenna
    - aeonik 3mo ago
      You nerd sniped with this one. I looked it up, and apparently utility companies already use the lines for comms, so you would be stomping on those potentially (depending on frequency). As for radiating... Possibly... But the tuning seems ridiculously hard/out of your control. The conductors are huge, and I can't imagine getting a stable RF standing wave across grid scale infra like that. I'm sure it's possible... Those lines are actually too long and changing electrical length for most useful RF. I'm going to have to dig a bit deeper though.
myotheraccount2 3mo ago
Here you go. https://theradiosource.com/products/antenna-630pd.htm https://theradiosource.com/products/antenna-630pd.htm
- aeonik 3mo ago
  This is amazing.
- microgpt 3mo ago
  I understand that while you can add substantial capacitance and inductance to make an "electrically long" short antenna for a long wavelength, its effectiveness at transmitting and receiving is still proportional to its size - the signal will be pretty weak?
  - microgpt 3mo ago
    Then I remembered the way these electrically short antennas work is by resonating the signal within themselves so you're basically transmitting a really high amount of power with a really low efficiency (and the rest stays confined between the antenna and its extra L/C loads until it gets transmitted).
dotwaffle 3mo ago
Before Radio 4 LW was renumbered in 1988, it was 200kHz. And before the early 70s it was referred to as it's wavelength... 1500m :P

by aeonik 3mo ago

microgpt 3mo ago

Does stapling it to your neighbours' fence lines and painting it like the wood count as creative? I wonder if you can couple to your local distribution grid, and not get arrested.

aeonik 3mo ago
I just string the antenna across my attic. Coupling into my power upstairs is a bit of a problem sometimes though. Pirating power is something I've heard that happens, but I looked it up, and couldn't find an actual cited example of someone doing it via induction. Plenty of people doing it via extension cords and device tampering though.
- ErroneousBosh 3mo ago
  > Coupling into my power upstairs is a bit of a problem sometimes though. I haven't worked with my end-fed on 40m for a couple of years. We've recently all had our crappy old aluminium-cored BT lines replaced with shiny new fibre though, so this time I am unlikely to lift the coveted Worked All DSLAMs trophy ;-)
- microgpt 3mo ago
  I meant feeding RF back into the power grid to use it as your very large antenna
  - aeonik 3mo ago
    You nerd sniped with this one. I looked it up, and apparently utility companies already use the lines for comms, so you would be stomping on those potentially (depending on frequency). As for radiating... Possibly... But the tuning seems ridiculously hard/out of your control. The conductors are huge, and I can't imagine getting a stable RF standing wave across grid scale infra like that. I'm sure it's possible... Those lines are actually too long and changing electrical length for most useful RF. I'm going to have to dig a bit deeper though.

myotheraccount2 3mo ago

Here you go. https://theradiosource.com/products/antenna-630pd.htm https://theradiosource.com/products/antenna-630pd.htm

aeonik 3mo ago
This is amazing.
microgpt 3mo ago
I understand that while you can add substantial capacitance and inductance to make an "electrically long" short antenna for a long wavelength, its effectiveness at transmitting and receiving is still proportional to its size - the signal will be pretty weak?
- microgpt 3mo ago
  Then I remembered the way these electrically short antennas work is by resonating the signal within themselves so you're basically transmitting a really high amount of power with a really low efficiency (and the rest stays confined between the antenna and its extra L/C loads until it gets transmitted).

dotwaffle 3mo ago

Before Radio 4 LW was renumbered in 1988, it was 200kHz. And before the early 70s it was referred to as it's wavelength... 1500m :P