4 ms·

Thanks for the references. As I suspected. You take an antenna cut for a band, try to use it on others and find its limits -- nothing abnormal there. Still, may

by myth2018 5y ago

Thanks for the references. As I suspected. You take an antenna cut for a band, try to use it on others and find its limits -- nothing abnormal there. Still, maybe something you could circumvent with additional devices to transform the impedance? I can't check the article now, but maybe some changes to form a counterpoise, or feeding the antenna at a different point, could adapt it without big investments -- if you're really willing to spend resources on such improvisation. And about AM, it doesn't transmit the full human-audible spectrum, so the channel is not that wide. Currently standards result in ~20KHz IIRC. BTW, some amateurs use receiving tunnable loops to listen to distant AM stations -- the antenna's narrow bandwidth is actually an advantage in such cases. And, again, someone interested in transmitting in AM or using some of those exotic modes have no reason whatsoever to worry about loop's bandwidths -- just look for an appropriate antenna and stop worrying. It doesn't make sense to try to hammer a nail with a slipper and complain about its sole not being hard enough.

mlyle 5y ago
> You take an antenna cut for a frequency, try to use it on others and find its limits The whole idea with a long, random wire is that it's not cut for a frequency, and happens to work well for most. This is about the most common case that exists, IMO :P There's nothing you can do for it to make it work well on those places where it's worst-- other than shorten or lengthen it. Yes, you can make it tune up by e.g. increasing ground losses, but that is not a win. (E.g. the T2FD does this deliberately, adding a shorting resistor to make the antenna tune anywhere). > Currently standards result in ~20KHz IIRC. AM is enormously variable depending upon band and operator. Yes, MW AM in the US is about 16KHz wide. Ecos del Torbes was frequently 35KHz wide, and sounded fantastic (better than broadcast FM) when it was strong and there weren't terrible atmospheric crashes. CRI is usually 30KHz wide. Witness the R390A, with a bandwidth KC (audio bandwidth) switch that goes to 16KHz. That's the -3dB point, too, and it rolls off relatively gently past where you have it switched. High fidelity AM was and is a thing. https://upload.wikimedia.org/wikipedia/commons/1/12/R390A.png https://upload.wikimedia.org/wikipedia/commons/1/12/R390A.pn... > It doesn't make sense to try to hammer a nail with a slipper and complain about its sole not being hard enough. No one has said that magnetic loops or long wire antennas are bad. I like them. I just pointed out the limitations and you disagreed.

mlyle 5y ago

> You take an antenna cut for a frequency, try to use it on others and find its limits The whole idea with a long, random wire is that it's not cut for a frequency, and happens to work well for most. This is about the most common case that exists, IMO :P There's nothing you can do for it to make it work well on those places where it's worst-- other than shorten or lengthen it. Yes, you can make it tune up by e.g. increasing ground losses, but that is not a win. (E.g. the T2FD does this deliberately, adding a shorting resistor to make the antenna tune anywhere). > Currently standards result in ~20KHz IIRC. AM is enormously variable depending upon band and operator. Yes, MW AM in the US is about 16KHz wide. Ecos del Torbes was frequently 35KHz wide, and sounded fantastic (better than broadcast FM) when it was strong and there weren't terrible atmospheric crashes. CRI is usually 30KHz wide. Witness the R390A, with a bandwidth KC (audio bandwidth) switch that goes to 16KHz. That's the -3dB point, too, and it rolls off relatively gently past where you have it switched. High fidelity AM was and is a thing. https://upload.wikimedia.org/wikipedia/commons/1/12/R390A.png https://upload.wikimedia.org/wikipedia/commons/1/12/R390A.pn... > It doesn't make sense to try to hammer a nail with a slipper and complain about its sole not being hard enough. No one has said that magnetic loops or long wire antennas are bad. I like them. I just pointed out the limitations and you disagreed.