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What's In a Name -- Of My Antenna?
On 3/26/2016 12:53 AM, Jeff Liebermann wrote:
On Fri, 25 Mar 2016 21:24:45 -0700, "Sal M. O'Nella" wrote: I don't know the correct definition, but my definition is an antenna array with inline elements. Those elements can be parasitic or driven. And they can be dipoles, quads, triangles or whatever. My definition of an antenna is a matching transformer which matched the output impedance of a transmitter, with that of free space (377 ohms). Convention has it to name the antenna after the designer. In this case, Shintaro Uda was the student assistant who designed the antenna, while Hidetsugu Yagi was his university instructor. Uda published a paper on the design in Japanese, which nobody seemed to have noticed. A few years later, Yagi translated the paper into English, which finally got some attention. Its publication resulted in the antenna being called a Yagi antenna by the American press. Yagi repeatedly reminded everyone that it was Uda who had designed the antenna, and deserved the credit. However, the best that could be done was the Yagi-Uda contraction, which is awkward and backwards. http://what-is-what.com/what_is/Yagi_Uda_antenna.html "Despite the fact that Hidetsugu Yagi never took credit for the antenna's design, it was his name that the American press used to refer to the concept." http://www.radiocomms.com.au/content/industry/article/yagi-the-man-behind-the-antenna-647231587 "The technology is all down to Prof Hidetsugu Yagi and his assistant Shintaro Uda; more to Uda than Yagi, in fact, so strictly speaking the design should be known as the Uda antenna, or at least Yagi-Uda." Incidentally, I have an FM broadcast Yagi-Uda antenna on my roof that was made by the Yagi-Uda Antenna Company (or something like that). I'll see if I can find the documentation and post a copy. Both of these pages were interesting, but hard to read. I don't get why some pages use a light grey text. I suppose some don't have a problem reading that, but I do, a *lot*. The other page intentionally added a shadow to the text, not just the headings or links, making that page even harder for me to read. I really don't get that either. I found a few more pages on Yagi-Uda antennas and some derivatives. One describes how to build a Quagi antenna where the driven element and the reflector are loops. Seems that works pretty well getting similar numbers to Yagi type antennas with more directors. What I really need in an antenna, is something I can add to the ubiquiti nanostation m900 loco I am using for Internet access. The internal antenna is only 7.5 dBi. I see a Yagi which is 13 dBi but it seems to be out of date. The current model is very fancy and is over $200. The other one is only $33. -- Rick |
#2
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What's In a Name -- Of My Antenna?
In message , rickman
writes Both of these pages were interesting, but hard to read. I don't get why some pages use a light grey text. I suppose some don't have a problem reading that, but I do, a *lot*. +1 It's plain stupid. Perhaps they think that they are saving 'ink'! A quick fix is to highlight the offending text. -- Ian |
#3
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What's In a Name -- Of My Antenna?
On 3/26/2016 4:20 AM, Ian Jackson wrote:
In message , rickman writes Both of these pages were interesting, but hard to read. I don't get why some pages use a light grey text. I suppose some don't have a problem reading that, but I do, a *lot*. +1 It's plain stupid. Perhaps they think that they are saving 'ink'! A quick fix is to highlight the offending text. Sometimes that is worse than the original, improves contrast, but horrid to read still. It does nothing for the shadowed text. That one is truly bizarre. I think it is a "style" thing. They are trying to be trendy. -- Rick |
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What's In a Name -- Of My Antenna?
On Sat, 26 Mar 2016 02:17:21 -0400, rickman wrote:
Both of these pages were interesting, but hard to read. I don't get why some pages use a light grey text. I suppose some don't have a problem reading that, but I do, a *lot*. The other page intentionally added a shadow to the text, not just the headings or links, making that page even harder for me to read. I really don't get that either. If you're using Firefox, click on the "reader view" icon. https://support.mozilla.org/en-US/kb/firefox-reader-view-clutter-free-web-pages There are similar features and plug-ins for other browsers. I see all too much of the "gray text" problem that inspired such things as "reader view". I agree, it sucks. It's the result of some of the really bad style sheets that are found in many CMS (content management system) web page creations. It's main benefit is that it emphasizes the advertising. It also holds your attention longer so that you stay on the web page longer. I can bore you with details on how this works in advertising if you're interested. I found a few more pages on Yagi-Uda antennas and some derivatives. One describes how to build a Quagi antenna where the driven element and the reflector are loops. Seems that works pretty well getting similar numbers to Yagi type antennas with more directors. Yep. A quagi is a square loop element. The big advantage of quagi and loop yagi antennas is that they squeeze a few more dB of gain (about 2-3dB) with the same boom length as a conventional yagi. That's not a trivial amount when you consider that in order to get 3dB more gain out of a yagi, the boom has to be twice as long. What I really need in an antenna, is something I can add to the ubiquiti nanostation m900 loco I am using for Internet access. The internal antenna is only 7.5 dBi. I see a Yagi which is 13 dBi but it seems to be out of date. The current model is very fancy and is over $200. The other one is only $33. I'm involved with a bunch of 900 MHz ham radio repeaters and had a fair amount of experience with 900 MHz. I don't like yagi antennas for 900 or 2.4GHz. I prefer patch or panel antennas. However, if you must buy a yagi, I suggest something by Antennex or something resold by Laird. By the time you get to 13 or 14dBi gain, the bandwidth of a yagi becomes sufficiently narrow that you'll loose gain at the band edges. Since your radio needs to hop from 902-928Mhz, you'll need an antenna that's fairly flat across the entire range. Just keep your eye on the VSWR vs Freq graphs to avoid this problem. http://www.lairdtech.com/product-categories/antennas/yagis http://www.l-com.com/wireless-antenna-900-mhz-yagi-antennas Gotta run... -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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What's In a Name -- Of My Antenna?
On 3/26/2016 1:14 PM, Jeff Liebermann wrote:
On Sat, 26 Mar 2016 02:17:21 -0400, rickman wrote: Both of these pages were interesting, but hard to read. I don't get why some pages use a light grey text. I suppose some don't have a problem reading that, but I do, a *lot*. The other page intentionally added a shadow to the text, not just the headings or links, making that page even harder for me to read. I really don't get that either. If you're using Firefox, click on the "reader view" icon. https://support.mozilla.org/en-US/kb/firefox-reader-view-clutter-free-web-pages There are similar features and plug-ins for other browsers. I see all too much of the "gray text" problem that inspired such things as "reader view". I agree, it sucks. It's the result of some of the really bad style sheets that are found in many CMS (content management system) web page creations. It's main benefit is that it emphasizes the advertising. It also holds your attention longer so that you stay on the web page longer. I can bore you with details on how this works in advertising if you're interested. I found a few more pages on Yagi-Uda antennas and some derivatives. One describes how to build a Quagi antenna where the driven element and the reflector are loops. Seems that works pretty well getting similar numbers to Yagi type antennas with more directors. Yep. A quagi is a square loop element. The big advantage of quagi and loop yagi antennas is that they squeeze a few more dB of gain (about 2-3dB) with the same boom length as a conventional yagi. That's not a trivial amount when you consider that in order to get 3dB more gain out of a yagi, the boom has to be twice as long. What I really need in an antenna, is something I can add to the ubiquiti nanostation m900 loco I am using for Internet access. The internal antenna is only 7.5 dBi. I see a Yagi which is 13 dBi but it seems to be out of date. The current model is very fancy and is over $200. The other one is only $33. I'm involved with a bunch of 900 MHz ham radio repeaters and had a fair amount of experience with 900 MHz. I don't like yagi antennas for 900 or 2.4GHz. I prefer patch or panel antennas. However, if you must buy a yagi, I suggest something by Antennex or something resold by Laird. By the time you get to 13 or 14dBi gain, the bandwidth of a yagi becomes sufficiently narrow that you'll loose gain at the band edges. Since your radio needs to hop from 902-928Mhz, you'll need an antenna that's fairly flat across the entire range. Just keep your eye on the VSWR vs Freq graphs to avoid this problem. http://www.lairdtech.com/product-categories/antennas/yagis http://www.l-com.com/wireless-antenna-900-mhz-yagi-antennas The datasheet for the NanoStationlocoM9 which seems to be the newer version of what I have has a return loss graph for the internal antenna. This seems to show a range centered on about 917 MHz and not too wide. It says the frequencies used are 902 to 928 MHz. I looked at the highest gain antennas from each of these two and neither supplies VSWR graphs. The Laird PC9013N has 13 elements and says freq range is 902 to 928 MHz which seems to roughly match the internal antenna. The L-com model HG914YE with 14 elements says it works from 824 to 960 MHz. It claims a 1.5:1 VSWR "average" which I guess means something, but I'm not sure what. This unit has 14 dBi of gain while the Laird is 13 dBi. I'm thinking 1 dB is not so much. The Laird seems to be well over $100 and the L-com around $50 with free shipping. I'll also need an N to SMA pigtail. First I need to ask my provider. He may have to twiddle something in the box to enable the antenna input. BTW, one of these antennas says the directors are welded to the boom. I always thought the elements were insulated from each other and the boom. I recall seeing insulation on old TV antennas, was that just to prevent corrosion or something? -- Rick |
#6
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What's In a Name -- Of My Antenna?
On Sat, 26 Mar 2016 14:08:12 -0400, rickman wrote:
The datasheet for the NanoStationlocoM9 which seems to be the newer version of what I have has a return loss graph for the internal antenna. This seems to show a range centered on about 917 MHz and not too wide. It says the frequencies used are 902 to 928 MHz. Unless Ubiquiti is doing something odd, if they use FHSS (frequency hopping spread spectrum), the radio must hop all 83 channels (in 1 MHz increments) within some interval that I'm too lazy to excavate from FCC Part 15. In effect, you'll see it hop the entire allocated frequency range. One source of confusion is whether an antenna has to TUNE over a frequency range, or whether it has to OPERATE over a frequency range. It's possible to find a narrow band FM 900 MHz antenna that will tune the desired range, but once tuned, has a much smaller operating bandwidth. High gain Yagi and big gain patch/panel antennas are potential problems. I looked at the highest gain antennas from each of these two and neither supplies VSWR graphs. The Laird PC9013N has 13 elements and says freq range is 902 to 928 MHz which seems to roughly match the internal antenna. The L-com model HG914YE with 14 elements says it works from 824 to 960 MHz. It claims a 1.5:1 VSWR "average" which I guess means something, but I'm not sure what. Average is not the usual term. I would have no problem with 1.5:1 maximum VSWR, but average sounds like they're hiding a problem. This unit has 14 dBi of gain while the Laird is 13 dBi. Many of the gain plots are simulations and are not the result of field tests or anechoic chamber tests. It's fairly easy to recognize the difference. The real tests show lower numbers and look far from idea. The simulations look too good. I'm thinking 1 dB is not so much. The Laird seems to be well over $100 and the L-com around $50 with free shipping. I'll also need an N to SMA pigtail. First I need to ask my provider. He may have to twiddle something in the box to enable the antenna input. Ask your WISP what kind of antenna he recommends. I doubt that this is the first higher gain antenna that he's installed. I still recommend using a panel antenna. I have a few in the office, but they're circular polarization for near field devices and probably won't work for you. Start he https://www.google.com/#q=900+mhz+panel+antenna Anything over about 10dBi gain should be sufficient. BTW, one of these antennas says the directors are welded to the boom. Yes. Good idea if you want it to survive. All of the Laird (Antenex) Yagi's that I've used were welded and had rounded ends to improve the bandwidth. They're more expensive than bolt together Yagi's but I think it's worth it for mountain top use, where I have to pay an expensive certified tower climber to deal with any damage. However, for the average consumer, it's probably overkill. I always thought the elements were insulated from each other and the boom. I recall seeing insulation on old TV antennas, was that just to prevent corrosion or something? No. It makes the TV antenna easy to ship in a smaller box. If TV antennas were welded and shipped ready to install, they would be huge, and the shipping would be seriously expensive. The elements of a Yagi do not need to insulated from the boom. However, the length of the elements is affected by the boom. The RF path goes around the boom in the welded design requiring 1/2 the circumference of the boom to be added to the element length calculation. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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What's In a Name -- Of My Antenna?
On 3/27/2016 5:12 PM, Jeff Liebermann wrote:
On Sat, 26 Mar 2016 14:08:12 -0400, rickman wrote: The datasheet for the NanoStationlocoM9 which seems to be the newer version of what I have has a return loss graph for the internal antenna. This seems to show a range centered on about 917 MHz and not too wide. It says the frequencies used are 902 to 928 MHz. Unless Ubiquiti is doing something odd, if they use FHSS (frequency hopping spread spectrum), the radio must hop all 83 channels (in 1 MHz increments) within some interval that I'm too lazy to excavate from FCC Part 15. In effect, you'll see it hop the entire allocated frequency range. One source of confusion is whether an antenna has to TUNE over a frequency range, or whether it has to OPERATE over a frequency range. It's possible to find a narrow band FM 900 MHz antenna that will tune the desired range, but once tuned, has a much smaller operating bandwidth. High gain Yagi and big gain patch/panel antennas are potential problems. I'm talking about the antenna built into a working unit. You seem to be discussing the state of the art in general. I looked at the highest gain antennas from each of these two and neither supplies VSWR graphs. The Laird PC9013N has 13 elements and says freq range is 902 to 928 MHz which seems to roughly match the internal antenna. The L-com model HG914YE with 14 elements says it works from 824 to 960 MHz. It claims a 1.5:1 VSWR "average" which I guess means something, but I'm not sure what. Average is not the usual term. I would have no problem with 1.5:1 maximum VSWR, but average sounds like they're hiding a problem. This unit has 14 dBi of gain while the Laird is 13 dBi. Many of the gain plots are simulations and are not the result of field tests or anechoic chamber tests. It's fairly easy to recognize the difference. The real tests show lower numbers and look far from idea. The simulations look too good. I'm thinking 1 dB is not so much. The Laird seems to be well over $100 and the L-com around $50 with free shipping. I'll also need an N to SMA pigtail. First I need to ask my provider. He may have to twiddle something in the box to enable the antenna input. Ask your WISP what kind of antenna he recommends. I doubt that this is the first higher gain antenna that he's installed. Bet it *is*! In fact, I bet the only high gain antenna he has installed was the point to point link to connect his antennas. He likely doesn't do the work himself since that requires climbing towers and likely a crane. Do they carry the components up by hand? I can't imagine they would. He said something about adding a tower in a few months which will add bandwidth to the system. But he has always said my air link was marginal when compared to my neighbors, at this point some 6 dB worse. I'd like to fix that. I know none of my nearest neighbors who get his service are even in the area. It is on a lake and one guy is only here on weekends in the summer and the other guy is only here a *few* weekends in the summer. He does have cameras that are accessed over the Internet, so they might use bandwidth all the time, don't know, maybe only when someone wants to look. He uses some third party service to make the connection. They might be recording all the time. I still recommend using a panel antenna. I have a few in the office, but they're circular polarization for near field devices and probably won't work for you. Start he https://www.google.com/#q=900+mhz+panel+antenna Anything over about 10dBi gain should be sufficient. The existing internal antenna is 7 dBi. I can't see going to the trouble of using an external antenna to get another 3 dB. I did find a couple of panel antennas that give 12.5 dB. They might be cheaper than the Yagi I found at $70. One panel was $40, but out of stock. BTW, one of these antennas says the directors are welded to the boom. Yes. Good idea if you want it to survive. All of the Laird (Antenex) Yagi's that I've used were welded and had rounded ends to improve the bandwidth. They're more expensive than bolt together Yagi's but I think it's worth it for mountain top use, where I have to pay an expensive certified tower climber to deal with any damage. However, for the average consumer, it's probably overkill. I always thought the elements were insulated from each other and the boom. I recall seeing insulation on old TV antennas, was that just to prevent corrosion or something? No. It makes the TV antenna easy to ship in a smaller box. If TV antennas were welded and shipped ready to install, they would be huge, and the shipping would be seriously expensive. Making them collapsible doesn't require insulators. Each folding element had a piece of what looked like card stock between the element and the mounting point on the boom. Was that to prevent corrosion maybe? I assume the active element is insulated, right? The elements of a Yagi do not need to insulated from the boom. However, the length of the elements is affected by the boom. The RF path goes around the boom in the welded design requiring 1/2 the circumference of the boom to be added to the element length calculation. -- Rick |
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What's In a Name -- Of My Antenna?
On 3/26/2016 1:14 PM, Jeff Liebermann wrote:
On Sat, 26 Mar 2016 02:17:21 -0400, rickman wrote: Both of these pages were interesting, but hard to read. I don't get why some pages use a light grey text. I suppose some don't have a problem reading that, but I do, a *lot*. The other page intentionally added a shadow to the text, not just the headings or links, making that page even harder for me to read. I really don't get that either. If you're using Firefox, click on the "reader view" icon. https://support.mozilla.org/en-US/kb/firefox-reader-view-clutter-free-web-pages There are similar features and plug-ins for other browsers. I just gave this a try. It completely changes the page formatting. It doesn't seem to work with just any page. Not sure about the capabilities, I'll have to play with it. Thanks -- Rick |
#9
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What's In a Name -- Of My Antenna?
In message , rickman
writes On 3/26/2016 1:14 PM, Jeff Liebermann wrote: On Sat, 26 Mar 2016 02:17:21 -0400, rickman wrote: Both of these pages were interesting, but hard to read. I don't get why some pages use a light grey text. I suppose some don't have a problem reading that, but I do, a *lot*. The other page intentionally added a shadow to the text, not just the headings or links, making that page even harder for me to read. I really don't get that either. If you're using Firefox, click on the "reader view" icon. https://support.mozilla.org/en-US/kb...-clutter-free- web-pages There are similar features and plug-ins for other browsers. I just gave this a try. It completely changes the page formatting. It doesn't seem to work with just any page. Not sure about the capabilities, I'll have to play with it. Thanks I hadn't realised that there WAS a "reader view". Thanks for the info! -- Ian |
#10
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What's In a Name -- Of My Antenna?
On Sat, 26 Mar 2016 14:13:01 -0400, rickman wrote:
On 3/26/2016 1:14 PM, Jeff Liebermann wrote: On Sat, 26 Mar 2016 02:17:21 -0400, rickman wrote: Both of these pages were interesting, but hard to read. I don't get why some pages use a light grey text. I suppose some don't have a problem reading that, but I do, a *lot*. The other page intentionally added a shadow to the text, not just the headings or links, making that page even harder for me to read. I really don't get that either. If you're using Firefox, click on the "reader view" icon. https://support.mozilla.org/en-US/kb/firefox-reader-view-clutter-free-web-pages There are similar features and plug-ins for other browsers. I just gave this a try. It completely changes the page formatting. It doesn't seem to work with just any page. Not sure about the capabilities, I'll have to play with it. Thanks This might be closer to what you're looking for. https://addons.mozilla.org/en-US/firefox/addon/blacken/ All it does is darken the text, without mangling the formatting. I just tried it and it does work as advertised. It initially didn't make text as dark as I would like, so I tweaked the settings. There are quite a few settings under: Tools - Add-ons - Extensions where the defaults are not particularly ideal. It has an "automatic" mode, which seems to recognize problem web pages with nearly invisible text. Blacken can be controlled with the "B" icon that was added to the Firefox toolbar. Try the "help" under the "B" icon for some details and capabilities. Here's the previous faded URL again for testing: http://www.radiocomms.com.au/content/industry/article/yagi-the-man-behind-the-antenna-647231587 -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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