Someone "invented" a previously unpublished military design.
Century means there is a factor of a hundred between lower and upper frequency that the antenna efficiently works on.
Decade means a factor of 10.
Bandwidth is typical the range of frequencies where the antenna is efficient.
Typically we categorise this by comparing it's gain at the centre frequency with how much you have to deviate before the gain drops some set amount.
Let's say it's resonant at 10GHz with a gain of 6dB. Typically we care about the range it's within 3dB of that.
Gain in this setting is less about amplification and more about concentrating the energy into a region of space rather than out in all directions.
If you go down to 3Ghz (probably 3.16GHz actually)and up to 30GHz( probably 31.6ghz)and it's still withing 3dB of 6dB, you have a decade bandwidth.
If you can do a century you're looking at 1 to 100GHz
An Octave is 1/sqrt(2) to sqrt(2) a decade is 1/sqrt(10) to sqrt(10) and a century is 1/sqrt(100) to sqrt(100) range.
So if you have an A4 note at 440Hz and you want a filter that captures an Octave with that A at its centre you would need a filter from 440/sqrt(2) =311 and 440×sqrt(2) = 622 which are d#4 and d#5. 6 semitones up from D#4 you get A4, another 6 and you have D#5. Musically it sounds like A4 is exactly between D#4 and D#5.
The fact that Century-bandwidth has a dash but decade bandwidth has not is weird, I didn't make the connection due to that (one sounded like a brand name, the other not)
The term "century-bandwidth" is always used in the article as a pre-noun adjective. The term "decade bandwidth" is not used that way. It's the difference between "a well-known author" and "an author who is well known".
Here is a basic explanation and a comment on the patent issue the author is addressing:
1. Antennas are designed to either transmit or receive RF.
2. The antenna is like water spigot for RF energy. If you design the antenna right, you can maximize the amount of RF energy you can get through it. This is equivalent to minimizing the impedance.
3. But, antennas are resonant. In other words the amount of RF that gets through can be maximum at one frequency (or a small range or bandwidth of frequencies), but very bad outside of that range.
4. Antenna designers try all kinds of tricks and techniques--including shapes, elements, delays, etc.--to try to get the antenna to have a broader resonance. An analogy might be the design of a musical instrument like the saxophone.
5. The VSWR the author mentions is a way of charting the resonance of the antenna with respect to frequency, ie. the bandwidth of the antenna.
6. Typical antennas (like a rod or something) have a bandwidth of maybe 5-10% of the center frequency.
7. Fancier antennas like a discone have a fractional bandwidth of up to 10:1.
8. An antenna like the one described by the author claimed to be 100:1.
9. But...even though the antenna may have broad bandwidth...the other factor antenna designers care about is gain (or loss). And this just complicates the design process even more.
Now, what I find most interesting about the author's comments is their suggestion that people continue to reinvent the wheel and then patent it. I too have seen this happen (not necessarily patents, but with other "technology inventions") over the years. I used to work in radio direction finding and every five or ten years someone would claim to have a new way of locating signals--but it's always just the same ideas over and over again. In other words, physics is physics.
"Antennas are designed to either transmit or receive RF". This isn't even close to realistic. Outside of amplified or active antennas, they have to be bidirectional devices. An active antenna is just a normal passive one with a non-linear junction attached.
Sometimes "to either x or y" doesn't mean "to do one of x or y", sometimes it means "to be able to do both x and y (but not necessarily at the same time purposefully)".
The thing about the article is that the new patent is basically the same as the almost 20yo design that the author got when a lab closed shop and he asked nicely to have it.
He also says that the "original" design was also not so original as there are previous publications with similar designs.
The antenna itself is just an antenna that works well over a very broad RF spectrum.
Hope someone will explain this
Someone "invented" a previously unpublished military design.
Century means there is a factor of a hundred between lower and upper frequency that the antenna efficiently works on.
Decade means a factor of 10.
Bandwidth is typical the range of frequencies where the antenna is efficient.
Typically we categorise this by comparing it's gain at the centre frequency with how much you have to deviate before the gain drops some set amount.
Let's say it's resonant at 10GHz with a gain of 6dB. Typically we care about the range it's within 3dB of that. Gain in this setting is less about amplification and more about concentrating the energy into a region of space rather than out in all directions.
If you go down to 3Ghz (probably 3.16GHz actually)and up to 30GHz( probably 31.6ghz)and it's still withing 3dB of 6dB, you have a decade bandwidth.
If you can do a century you're looking at 1 to 100GHz
An Octave is 1/sqrt(2) to sqrt(2) a decade is 1/sqrt(10) to sqrt(10) and a century is 1/sqrt(100) to sqrt(100) range.
So if you have an A4 note at 440Hz and you want a filter that captures an Octave with that A at its centre you would need a filter from 440/sqrt(2) =311 and 440×sqrt(2) = 622 which are d#4 and d#5. 6 semitones up from D#4 you get A4, another 6 and you have D#5. Musically it sounds like A4 is exactly between D#4 and D#5.
The fact that Century-bandwidth has a dash but decade bandwidth has not is weird, I didn't make the connection due to that (one sounded like a brand name, the other not)
The term "century-bandwidth" is always used in the article as a pre-noun adjective. The term "decade bandwidth" is not used that way. It's the difference between "a well-known author" and "an author who is well known".
Here is a basic explanation and a comment on the patent issue the author is addressing:
1. Antennas are designed to either transmit or receive RF.
2. The antenna is like water spigot for RF energy. If you design the antenna right, you can maximize the amount of RF energy you can get through it. This is equivalent to minimizing the impedance.
3. But, antennas are resonant. In other words the amount of RF that gets through can be maximum at one frequency (or a small range or bandwidth of frequencies), but very bad outside of that range.
4. Antenna designers try all kinds of tricks and techniques--including shapes, elements, delays, etc.--to try to get the antenna to have a broader resonance. An analogy might be the design of a musical instrument like the saxophone.
5. The VSWR the author mentions is a way of charting the resonance of the antenna with respect to frequency, ie. the bandwidth of the antenna.
6. Typical antennas (like a rod or something) have a bandwidth of maybe 5-10% of the center frequency.
7. Fancier antennas like a discone have a fractional bandwidth of up to 10:1.
8. An antenna like the one described by the author claimed to be 100:1.
9. But...even though the antenna may have broad bandwidth...the other factor antenna designers care about is gain (or loss). And this just complicates the design process even more.
Now, what I find most interesting about the author's comments is their suggestion that people continue to reinvent the wheel and then patent it. I too have seen this happen (not necessarily patents, but with other "technology inventions") over the years. I used to work in radio direction finding and every five or ten years someone would claim to have a new way of locating signals--but it's always just the same ideas over and over again. In other words, physics is physics.
"Antennas are designed to either transmit or receive RF". This isn't even close to realistic. Outside of amplified or active antennas, they have to be bidirectional devices. An active antenna is just a normal passive one with a non-linear junction attached.
Sometimes "to either x or y" doesn't mean "to do one of x or y", sometimes it means "to be able to do both x and y (but not necessarily at the same time purposefully)".
Can anyone explain it in a few sentences cos I still don't get it
The thing about the article is that the new patent is basically the same as the almost 20yo design that the author got when a lab closed shop and he asked nicely to have it.
He also says that the "original" design was also not so original as there are previous publications with similar designs.
The antenna itself is just an antenna that works well over a very broad RF spectrum.
So no one has done anything wrong, but researchers find it difficult to understand the breadth of prior research and therefore end up duplicating it?
someone patented something in 2006 that the author had already acquired one of in 1986
tldr, the prose was too terse
(2006)