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LPY antenna designs?
Anyone have any practical LPY (log-periodic Yagi) antenna designs they
care to share? Something with about 4% or 5% bandwidth in the VHF/low UHF range should do well--the element diameters should be appropriate for scaling the design to my frequencies of interest. 10dBi or so gain is probably fine. Cheers, Tom |
LPY antenna designs?
"K7ITM" wrote in message ... Anyone have any practical LPY (log-periodic Yagi) antenna designs they care to share? Something with about 4% or 5% bandwidth in the VHF/low UHF range should do well--the element diameters should be appropriate for scaling the design to my frequencies of interest. 10dBi or so gain is probably fine. Cheers, Tom define "log period yagi"??? ramsey has a line of products that they call 'log periodic and yagi' pcb antennas that has apparently been smushed into "LPY" as the prefix to their part numbers... but 'Yagi' antennas are one thing, and 'Log Periodic Dipole Array' antennas are something else. The only place they cross practically that i have seen is the use of a log periodic section feed section in between yagi style tuned parasitic elements to give a wider bandwidth feed point... in this case it is usually just 2 or 3 elements worth of lpda feeding the yagi which i have always considered just a way to add buzzwords to your antenna design description. |
LPY antenna designs?
On Feb 24, 4:37 am, "Dave" wrote:
"K7ITM" wrote in message ... Anyone have any practical LPY (log-periodic Yagi) antenna designs they care to share? Something with about 4% or 5% bandwidth in the VHF/low UHF range should do well--the element diameters should be appropriate for scaling the design to my frequencies of interest. 10dBi or so gain is probably fine. Cheers, Tom define "log period yagi"??? ramsey has a line of products that they call 'log periodic and yagi' pcb antennas that has apparently been smushed into "LPY" as the prefix to their part numbers... but 'Yagi' antennas are one thing, and 'Log Periodic Dipole Array' antennas are something else. The only place they cross practically that i have seen is the use of a log periodic section feed section in between yagi style tuned parasitic elements to give a wider bandwidth feed point... in this case it is usually just 2 or 3 elements worth of lpda feeding the yagi which i have always considered just a way to add buzzwords to your antenna design description. Yes, that's the design. I have data on a couple that suggest a pretty "flat" gain across a modest range of frequencies, with a relatively abrupt drop in gain outside that range. Googling got me to the printed circuit antennas (I guess for wireless networks and the like), but they aren't suitable to scale for what I want to do--too many things different about them (flat elements on a dielectric substrate, versus round elements in air). Cheers, Tom |
LPY antenna designs?
"K7ITM" wrote in message ... On Feb 24, 4:37 am, "Dave" wrote: "K7ITM" wrote in message ... Anyone have any practical LPY (log-periodic Yagi) antenna designs they care to share? Something with about 4% or 5% bandwidth in the VHF/low UHF range should do well--the element diameters should be appropriate for scaling the design to my frequencies of interest. 10dBi or so gain is probably fine. Cheers, Tom define "log period yagi"??? ramsey has a line of products that they call 'log periodic and yagi' pcb antennas that has apparently been smushed into "LPY" as the prefix to their part numbers... but 'Yagi' antennas are one thing, and 'Log Periodic Dipole Array' antennas are something else. The only place they cross practically that i have seen is the use of a log periodic section feed section in between yagi style tuned parasitic elements to give a wider bandwidth feed point... in this case it is usually just 2 or 3 elements worth of lpda feeding the yagi which i have always considered just a way to add buzzwords to your antenna design description. Yes, that's the design. I have data on a couple that suggest a pretty "flat" gain across a modest range of frequencies, with a relatively abrupt drop in gain outside that range. Googling got me to the printed circuit antennas (I guess for wireless networks and the like), but they aren't suitable to scale for what I want to do--too many things different about them (flat elements on a dielectric substrate, versus round elements in air). Cheers, Tom for hf you want to look for 'owa', "optimized wideband array" antennas, and also for yagi designs with dual driven elements like the m-squared 40m4lldd. The advantages are a wider swr bandwidth and perhaps an improvement in the gain or f/b bandwidth. you may also find some info searching for 'lpda-yagi' hybrids, though probably most of those are more for vhf/uhf. |
LPY antenna designs?
On Feb 25, 1:28 pm, "Dave" wrote:
"K7ITM" wrote in message ... On Feb 24, 4:37 am, "Dave" wrote: "K7ITM" wrote in message ... Anyone have any practical LPY (log-periodic Yagi) antenna designs they care to share? Something with about 4% or 5% bandwidth in the VHF/low UHF range should do well--the element diameters should be appropriate for scaling the design to my frequencies of interest. 10dBi or so gain is probably fine. Cheers, Tom define "log period yagi"??? ramsey has a line of products that they call 'log periodic and yagi' pcb antennas that has apparently been smushed into "LPY" as the prefix to their part numbers... but 'Yagi' antennas are one thing, and 'Log Periodic Dipole Array' antennas are something else. The only place they cross practically that i have seen is the use of a log periodic section feed section in between yagi style tuned parasitic elements to give a wider bandwidth feed point... in this case it is usually just 2 or 3 elements worth of lpda feeding the yagi which i have always considered just a way to add buzzwords to your antenna design description. Yes, that's the design. I have data on a couple that suggest a pretty "flat" gain across a modest range of frequencies, with a relatively abrupt drop in gain outside that range. Googling got me to the printed circuit antennas (I guess for wireless networks and the like), but they aren't suitable to scale for what I want to do--too many things different about them (flat elements on a dielectric substrate, versus round elements in air). Cheers, Tom for hf you want to look for 'owa', "optimized wideband array" antennas, and also for yagi designs with dual driven elements like the m-squared 40m4lldd. The advantages are a wider swr bandwidth and perhaps an improvement in the gain or f/b bandwidth. you may also find some info searching for 'lpda-yagi' hybrids, though probably most of those are more for vhf/uhf. Hi Dave, and thanks for the reply. I'll try some searches on those keywords. Often, just finding the right keyword for a search is well over half the battle. I perhaps didn't make it clear that I'm interested in optimizing the design for my particular application, which is up around 450MHz, so designs already at VHF/low-UHF are probably going to have reasonable element diameter-to-length ratios and may offer some ideas about good mechanical design. I'll happily spend some time with simulations to optimize the design for my application, but it helps a lot to start with a design that's close to what I want in the final implementation at least with respect to d/l ratios and percentage bandwidth. Cheers, Tom |
LPY antenna designs?
what's the high and low frequency you want to cover and how long do you want the boom to be? me On Sun, 24 Feb 2008 18:17:58 -0800 (PST), K7ITM wrote: On Feb 24, 4:37 am, "Dave" wrote: "K7ITM" wrote in message ... Anyone have any practical LPY (log-periodic Yagi) antenna designs they care to share? Something with about 4% or 5% bandwidth in the VHF/low UHF range should do well--the element diameters should be appropriate for scaling the design to my frequencies of interest. 10dBi or so gain is probably fine. Cheers, Tom |
LPY antenna designs?
On Feb 26, 7:07 pm, wrote:
what's the high and low frequency you want to cover and how long do you want the boom to be? me On Sun, 24 Feb 2008 18:17:58 -0800 (PST), K7ITM wrote: On Feb 24, 4:37 am, "Dave" wrote: "K7ITM" wrote in message ... Anyone have any practical LPY (log-periodic Yagi) antenna designs they care to share? Something with about 4% or 5% bandwidth in the VHF/low UHF range should do well--the element diameters should be appropriate for scaling the design to my frequencies of interest. 10dBi or so gain is probably fine. Cheers, Tom Let's see...500MHz to 1.05*500MHz = 525MHz; boom long enough to get me about 10dBi over that range. I'll scale it to my particular frequencies of interest, so any other ~5% bandwidth in that general vicinity of frequencies would be fine too. Cheers, Tom |
LPY antenna designs?
On Tue, 26 Feb 2008 23:02:37 -0800 (PST), K7ITM wrote:
Let's see...500MHz to 1.05*500MHz = 525MHz; boom long enough to get me about 10dBi over that range. I'll scale it to my particular frequencies of interest, so any other ~5% bandwidth in that general vicinity of frequencies would be fine too. Cheers, Tom This is a Log Periodic design. Double booms, 1 inch square, spaced 1.4 inches c-c. Boom length ~55 inches. Sweep for 500-525 MHz Free Space Gain - 11.6 - 12.6 dBi vswr 1.7:1.0 X is the position of the element along the boom. Y is the length of each "half-element". With a double boom design, one half of the dipole is mounted to one boom and the other half is mounted to the other boom. Coax attached to the front of the booms, shield to one, center to the other. Do not run coax between the booms. Booms can be electrically shorted to each other behind element # 1. You don't have to be this accurate, my calculator defaults to 5 places. Simply convert lenghts to the nearest mm is the easiest. x y End 0 1 2, 5.78592, 2 6.16586, 5.61234, 3 10.2067, 5.44397, 4 14.1264, 5.28065, 5 17.9285, 5.12223, 6 21.6165, 4.96857, 7 25.1939, 4.81951, 8 28.6639, 4.67492, 9 32.0299, 4.53468, 10 35.2948 , 4.39864, 11 38.4618, 4.26668, 12 41.5338, 4.13868, 13 44.5137 ,4.01452 14 47.4041 , 3.89408, 15 50.2079, 3.77726, 16 52.9275, 3.66394, End 54.9275 have fun |
LPY antenna designs?
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LPY antenna designs?
On Feb 27, 8:06 pm, wrote:
On Wed, 27 Feb 2008 22:29:01 -0500, wrote: On Tue, 26 Feb 2008 23:02:37 -0800 (PST), K7ITM wrote: Let's see...500MHz to 1.05*500MHz = 525MHz; boom long enough to get me about 10dBi over that range. I'll scale it to my particular frequencies of interest, so any other ~5% bandwidth in that general vicinity of frequencies would be fine too. Cheers, Tom Log-Yagi design. Four driven elements, reflector & director. Probably about 8 dBi maybe. Ele Length Position R 1.019' 0 DR1 0.984' 0.168' DR2 0.924' 0.266' DR3 0.868' 0.359' DR4 0.815' 0.446' D 0.902' 0.742' Split DR1-DR4 and transpose feed. Place hairpin at DR1 if needed for matching. Thanks for both those designs. I'll have a look at them and see if I can get reasonable modeling results, probably this weekend. I'd about given up that anyone would have any designs to offer, and appreciate that you put some effort into the replies. Cheers, Tom |
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