[time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation
Hello Time Nuts, I hope this isn't too off topic. Can I please have some recommendations for a decent active or passive GPS Antenna to add to the antenna farm that doesn't break the ole' piggy bank? Thanks In Advance, John Westmoreland ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation
Hello Time Nuts, I hope this isn't too off topic. Can I please have some recommendations for a decent active or passive GPS Antenna to add to the antenna farm that doesn't break the ole' piggy bank? Thanks In Advance, John Westmoreland == How decent do you want, John? Here's my GPS antenna farm: http://www.satsignal.eu/ntp/2013-03-31-1226-32-GPS-antenna-farm.jpg and I don't think any cost more than GBP 10. Perhaps your requirements are more stringent than mine (I think all the PPS outputs from the connected receivers are within 0.1 microseconds). I have a couple of timing antennas in the loft, but I can't see any difference between those and the magnetic pucks, for the precision level I need. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation
Hello David, Thanks for the pic! Well, I need something that I can put outside, in the weather, with my verticals, and other antennas. I am a Ham radio enthusiast, and I want something I can properly mount and can be an all-weather device and can live happily 'in the farm' so to speak. I should have been more specific. Thanks Again, John Westmoreland AJ6BC - (that's my call sign) On Sun, Sep 15, 2013 at 1:51 AM, David J Taylor david-tay...@blueyonder.co.uk wrote: Hello Time Nuts, I hope this isn't too off topic. Can I please have some recommendations for a decent active or passive GPS Antenna to add to the antenna farm that doesn't break the ole' piggy bank? Thanks In Advance, John Westmoreland ==** How decent do you want, John? Here's my GPS antenna farm: http://www.satsignal.eu/ntp/**2013-03-31-1226-32-GPS-**antenna-farm.jpghttp://www.satsignal.eu/ntp/2013-03-31-1226-32-GPS-antenna-farm.jpg and I don't think any cost more than GBP 10. Perhaps your requirements are more stringent than mine (I think all the PPS outputs from the connected receivers are within 0.1 microseconds). I have a couple of timing antennas in the loft, but I can't see any difference between those and the magnetic pucks, for the precision level I need. Cheers, David -- SatSignal Software - Quality software written to your requirements Web: http://www.satsignal.eu Email: david-tay...@blueyonder.co.uk __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation
Hi John: For an illustrated list of some GPS antennas (including voltages currents for active ones) see: http://www.prc68.com/I/DAGR.shtml#Ant Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html John C. Westmoreland, P.E. wrote: Hello Time Nuts, I hope this isn't too off topic. Can I please have some recommendations for a decent active or passive GPS Antenna to add to the antenna farm that doesn't break the ole' piggy bank? Thanks In Advance, John Westmoreland ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation
j...@westmorelandengineering.com said: Well, I need something that I can put outside, in the weather, with my verticals, and other antennas. I am a Ham radio enthusiast, and I want something I can properly mount and can be an all-weather device and can live happily 'in the farm' so to speak. I split GPS antennas into 3 clumps. At the low cost end are the small mouse or hockey-puck type units, usually with a magnetic mount. They typically come with 10 or 15 feet of thin (lossy) cable. Ballpark price is $10. In the middle are the typical cones that you see on cell phone stations. The Lucent 26 dB ones are common on eBay. Ballpark price is $50. The same or very similar thing is also available with different brand names. Some of them come with a pipe mounting setup such that the coax and connector is inside the pipe and out of the weather. http://www.megapathdsl.net/~hmurray/time-nuts/Lucent-Antenna.jpg At the top end are the choke ring antennas intended for surveying. They are mostly out of my price range so I haven't looked carefully. -- I haven't seen a GPS antenna without an amplifier, but I haven't been looking. They also include a filter. See the LightSquared flame-wars for a discussion of filters. I think the choke ring antennas usually let L1 and L2 through while most others are L1 only. The other important consideration is the sensitivity of your receiver. Every couple of years a new generation comes out that is a few dB better than the previous ones. (Has anybody seen a Moore's Law type graph?) Modern receivers are sensitive enough to work indoors with a non-fancy antenna, at least most of the time. YMMV etc, and indoors probably doesn't include buildings with a lot of steel. It doesn't cost much to try. If you have an old recycled GPSDO such as a TBolt or Z3801A, the receiver is much less sensitive and a good antenna position helps a lot. Of course, it also depends upon what you want to do and/or how nutty you are feeling. There is yet another dimension. GPS receivers come in two modes: navigation and timing. Navigation units need 3 or 4 satellites to figure out where (and when) they are located. The timing units assume they are not moving and that they know their location. They should be able to maintain timing with only 1 satellite. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation
On 9/15/13 1:36 PM, Hal Murray wrote: j...@westmorelandengineering.com said: Well, I need something that I can put outside, in the weather, with my verticals, and other antennas. I am a Ham radio enthusiast, and I want something I can properly mount and can be an all-weather device and can live happily 'in the farm' so to speak. I split GPS antennas into 3 clumps. At the low cost end are the small mouse or hockey-puck type units, usually with a magnetic mount. They typically come with 10 or 15 feet of thin (lossy) cable. Ballpark price is $10. In the middle are the typical cones that you see on cell phone stations. The Lucent 26 dB ones are common on eBay. Ballpark price is $50. The same or very similar thing is also available with different brand names. Some of them come with a pipe mounting setup such that the coax and connector is inside the pipe and out of the weather. http://www.megapathdsl.net/~hmurray/time-nuts/Lucent-Antenna.jpg At the top end are the choke ring antennas intended for surveying. They are mostly out of my price range so I haven't looked carefully. -- I haven't seen a GPS antenna without an amplifier, but I haven't been looking. They also include a filter. See the LightSquared flame-wars for a discussion of filters. I think the choke ring antennas usually let L1 and L2 through while most others are L1 only. Or, it might be that the choke ring is tuned for L1, but not L2/L5. Multiband choke rings are more complex than single band ones. the classic Dorne Margolin/JPL choke ring is pretty straighforward, and, in fact, one can do the nested cake pan thing to get pretty close. The multiband choke rings have segments and steps. The Leica ones I've used are termed artichokes because that is what they look like. Topcon has some really funky looking ones with mushroom shaped rods sticking out. The other important consideration is the sensitivity of your receiver. Every couple of years a new generation comes out that is a few dB better than the previous ones. (Has anybody seen a Moore's Law type graph?) I'd find few dB hard to believe. The NF of most LNAs these days is sub 2 dB, so changes are going to be in the tenths of a dB range. Modern receivers are sensitive enough to work indoors with a non-fancy antenna, at least most of the time. YMMV etc, and indoors probably doesn't include buildings with a lot of steel. It doesn't cost much to try. Sensitivity probably isn't the issue. Multipath is probably the dominant error source. If you have an old recycled GPSDO such as a TBolt or Z3801A, the receiver is much less sensitive and a good antenna position helps a lot. Of course, it also depends upon what you want to do and/or how nutty you are feeling. My Z3801 uses an antenna with a built in LNA, which is typical. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation
Hi Worth noting: The mid class antennas are not a lot different electrically than the low end antennas. The main differences are mechanical: 1) You get a much more weather tight housing 2) You get a rational way to mount the antenna 3) There's a connector on it so you can put a good piece of coax on it 4) The housing *may* be more immune to snow / ice buildup and bird nests RDR Electronics on the usual auction site appears to be selling some nice ones at the moment. Bob On Sep 15, 2013, at 4:36 PM, Hal Murray hmur...@megapathdsl.net wrote: j...@westmorelandengineering.com said: Well, I need something that I can put outside, in the weather, with my verticals, and other antennas. I am a Ham radio enthusiast, and I want something I can properly mount and can be an all-weather device and can live happily 'in the farm' so to speak. I split GPS antennas into 3 clumps. At the low cost end are the small mouse or hockey-puck type units, usually with a magnetic mount. They typically come with 10 or 15 feet of thin (lossy) cable. Ballpark price is $10. In the middle are the typical cones that you see on cell phone stations. The Lucent 26 dB ones are common on eBay. Ballpark price is $50. The same or very similar thing is also available with different brand names. Some of them come with a pipe mounting setup such that the coax and connector is inside the pipe and out of the weather. http://www.megapathdsl.net/~hmurray/time-nuts/Lucent-Antenna.jpg At the top end are the choke ring antennas intended for surveying. They are mostly out of my price range so I haven't looked carefully. -- I haven't seen a GPS antenna without an amplifier, but I haven't been looking. They also include a filter. See the LightSquared flame-wars for a discussion of filters. I think the choke ring antennas usually let L1 and L2 through while most others are L1 only. The other important consideration is the sensitivity of your receiver. Every couple of years a new generation comes out that is a few dB better than the previous ones. (Has anybody seen a Moore's Law type graph?) Modern receivers are sensitive enough to work indoors with a non-fancy antenna, at least most of the time. YMMV etc, and indoors probably doesn't include buildings with a lot of steel. It doesn't cost much to try. If you have an old recycled GPSDO such as a TBolt or Z3801A, the receiver is much less sensitive and a good antenna position helps a lot. Of course, it also depends upon what you want to do and/or how nutty you are feeling. There is yet another dimension. GPS receivers come in two modes: navigation and timing. Navigation units need 3 or 4 satellites to figure out where (and when) they are located. The timing units assume they are not moving and that they know their location. They should be able to maintain timing with only 1 satellite. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation
Hi On Sep 15, 2013, at 5:18 PM, Jim Lux jim...@earthlink.net wrote: On 9/15/13 1:36 PM, Hal Murray wrote: j...@westmorelandengineering.com said: Well, I need something that I can put outside, in the weather, with my verticals, and other antennas. I am a Ham radio enthusiast, and I want something I can properly mount and can be an all-weather device and can live happily 'in the farm' so to speak. I split GPS antennas into 3 clumps. At the low cost end are the small mouse or hockey-puck type units, usually with a magnetic mount. They typically come with 10 or 15 feet of thin (lossy) cable. Ballpark price is $10. In the middle are the typical cones that you see on cell phone stations. The Lucent 26 dB ones are common on eBay. Ballpark price is $50. The same or very similar thing is also available with different brand names. Some of them come with a pipe mounting setup such that the coax and connector is inside the pipe and out of the weather. http://www.megapathdsl.net/~hmurray/time-nuts/Lucent-Antenna.jpg At the top end are the choke ring antennas intended for surveying. They are mostly out of my price range so I haven't looked carefully. -- I haven't seen a GPS antenna without an amplifier, but I haven't been looking. They also include a filter. See the LightSquared flame-wars for a discussion of filters. I think the choke ring antennas usually let L1 and L2 through while most others are L1 only. Or, it might be that the choke ring is tuned for L1, but not L2/L5. Multiband choke rings are more complex than single band ones. the classic Dorne Margolin/JPL choke ring is pretty straighforward, and, in fact, one can do the nested cake pan thing to get pretty close. The multiband choke rings have segments and steps. The Leica ones I've used are termed artichokes because that is what they look like. Topcon has some really funky looking ones with mushroom shaped rods sticking out. The other important consideration is the sensitivity of your receiver. Every couple of years a new generation comes out that is a few dB better than the previous ones. (Has anybody seen a Moore's Law type graph?) I'd find few dB hard to believe. The NF of most LNAs these days is sub 2 dB, so changes are going to be in the tenths of a dB range. The increase in sensitivity comes from a massive increase in the number of correlators in the newer chips. More or less it allows them to dig further into the noise. Bob Modern receivers are sensitive enough to work indoors with a non-fancy antenna, at least most of the time. YMMV etc, and indoors probably doesn't include buildings with a lot of steel. It doesn't cost much to try. Sensitivity probably isn't the issue. Multipath is probably the dominant error source. If you have an old recycled GPSDO such as a TBolt or Z3801A, the receiver is much less sensitive and a good antenna position helps a lot. Of course, it also depends upon what you want to do and/or how nutty you are feeling. My Z3801 uses an antenna with a built in LNA, which is typical. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation
Hi Bob, Many of the midrange antennas have one or more significant differences from the cheap pucks. Firstly they generally have better filtering, many pucks have none. This is important if you are co-located with transmitters. Secondly many use quad-helix antenna elements rather than the off-set feed ceramic patches in the pucks. The heical elements have better control of the radiation pattern and along with a larger radome are less likely to be affected by external contamination. I also wonder how the tuning of a cheap ceramic patch holds up over the range of temperatures seen by a fixed antenna. Modern receivers compensate well for poor antennas, try using an early receiver on an internal patch and you won't get great results. Robert G8RPI. From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, 15 September 2013, 22:19 Subject: Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation Hi Worth noting: The mid class antennas are not a lot different electrically than the low end antennas. The main differences are mechanical: 1) You get a much more weather tight housing 2) You get a rational way to mount the antenna 3) There's a connector on it so you can put a good piece of coax on it 4) The housing *may* be more immune to snow / ice buildup and bird nests RDR Electronics on the usual auction site appears to be selling some nice ones at the moment. Bob On Sep 15, 2013, at 4:36 PM, Hal Murray hmur...@megapathdsl.net wrote: j...@westmorelandengineering.com said: Well, I need something that I can put outside, in the weather, with my verticals, and other antennas. I am a Ham radio enthusiast, and I want something I can properly mount and can be an all-weather device and can live happily 'in the farm' so to speak. I split GPS antennas into 3 clumps. At the low cost end are the small mouse or hockey-puck type units, usually with a magnetic mount. They typically come with 10 or 15 feet of thin (lossy) cable. Ballpark price is $10. In the middle are the typical cones that you see on cell phone stations. The Lucent 26 dB ones are common on eBay. Ballpark price is $50. The same or very similar thing is also available with different brand names. Some of them come with a pipe mounting setup such that the coax and connector is inside the pipe and out of the weather. http://www.megapathdsl.net/~hmurray/time-nuts/Lucent-Antenna.jpg At the top end are the choke ring antennas intended for surveying. They are mostly out of my price range so I haven't looked carefully. -- I haven't seen a GPS antenna without an amplifier, but I haven't been looking. They also include a filter. See the LightSquared flame-wars for a discussion of filters. I think the choke ring antennas usually let L1 and L2 through while most others are L1 only. The other important consideration is the sensitivity of your receiver. Every couple of years a new generation comes out that is a few dB better than the previous ones. (Has anybody seen a Moore's Law type graph?) Modern receivers are sensitive enough to work indoors with a non-fancy antenna, at least most of the time. YMMV etc, and indoors probably doesn't include buildings with a lot of steel. It doesn't cost much to try. If you have an old recycled GPSDO such as a TBolt or Z3801A, the receiver is much less sensitive and a good antenna position helps a lot. Of course, it also depends upon what you want to do and/or how nutty you are feeling. There is yet another dimension. GPS receivers come in two modes: navigation and timing. Navigation units need 3 or 4 satellites to figure out where (and when) they are located. The timing units assume they are not moving and that they know their location. They should be able to maintain timing with only 1 satellite. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation
Hi All of the ones I've opened up or seen dis-assembled have had the ceramic plate antennas in them. That very much surprised me early on, since I *assumed* they had something fancy inside based on their shape. No argument about the filtering, I'm not sure if the temp-co of filter delay on an exposed antenna makes it a plus or a minus…. Bob On Sep 15, 2013, at 5:48 PM, Robert Atkinson robert8...@yahoo.co.uk wrote: Hi Bob, Many of the midrange antennas have one or more significant differences from the cheap pucks. Firstly they generally have better filtering, many pucks have none. This is important if you are co-located with transmitters. Secondly many use quad-helix antenna elements rather than the off-set feed ceramic patches in the pucks. The heical elements have better control of the radiation pattern and along with a larger radome are less likely to be affected by external contamination. I also wonder how the tuning of a cheap ceramic patch holds up over the range of temperatures seen by a fixed antenna. Modern receivers compensate well for poor antennas, try using an early receiver on an internal patch and you won't get great results. Robert G8RPI. From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, 15 September 2013, 22:19 Subject: Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation Hi Worth noting: The mid class antennas are not a lot different electrically than the low end antennas. The main differences are mechanical: 1) You get a much more weather tight housing 2) You get a rational way to mount the antenna 3) There's a connector on it so you can put a good piece of coax on it 4) The housing *may* be more immune to snow / ice buildup and bird nests RDR Electronics on the usual auction site appears to be selling some nice ones at the moment. Bob On Sep 15, 2013, at 4:36 PM, Hal Murray hmur...@megapathdsl.net wrote: j...@westmorelandengineering.com said: Well, I need something that I can put outside, in the weather, with my verticals, and other antennas. I am a Ham radio enthusiast, and I want something I can properly mount and can be an all-weather device and can live happily 'in the farm' so to speak. I split GPS antennas into 3 clumps. At the low cost end are the small mouse or hockey-puck type units, usually with a magnetic mount. They typically come with 10 or 15 feet of thin (lossy) cable. Ballpark price is $10. In the middle are the typical cones that you see on cell phone stations. The Lucent 26 dB ones are common on eBay. Ballpark price is $50. The same or very similar thing is also available with different brand names. Some of them come with a pipe mounting setup such that the coax and connector is inside the pipe and out of the weather. http://www.megapathdsl.net/~hmurray/time-nuts/Lucent-Antenna.jpg At the top end are the choke ring antennas intended for surveying. They are mostly out of my price range so I haven't looked carefully. -- I haven't seen a GPS antenna without an amplifier, but I haven't been looking. They also include a filter. See the LightSquared flame-wars for a discussion of filters. I think the choke ring antennas usually let L1 and L2 through while most others are L1 only. The other important consideration is the sensitivity of your receiver. Every couple of years a new generation comes out that is a few dB better than the previous ones. (Has anybody seen a Moore's Law type graph?) Modern receivers are sensitive enough to work indoors with a non-fancy antenna, at least most of the time. YMMV etc, and indoors probably doesn't include buildings with a lot of steel. It doesn't cost much to try. If you have an old recycled GPSDO such as a TBolt or Z3801A, the receiver is much less sensitive and a good antenna position helps a lot. Of course, it also depends upon what you want to do and/or how nutty you are feeling. There is yet another dimension. GPS receivers come in two modes: navigation and timing. Navigation units need 3 or 4 satellites to figure out where (and when) they are located. The timing units assume they are not moving and that they know their location. They should be able to maintain timing with only 1 satellite. -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time
Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation
On 9/15/13 4:33 PM, Bob Camp wrote: Hi All of the ones I've opened up or seen dis-assembled have had the ceramic plate antennas in them. That very much surprised me early on, since I *assumed* they had something fancy inside based on their shape. I don't know that the thermal expansion effects on the ceramic or the antenna elements would be all that huge (it's a wideband low-Q device, after all), compared, say, to the CTE effects on the coax, or the temperature effects on components inside the LNA. No argument about the filtering, I'm not sure if the temp-co of filter delay on an exposed antenna makes it a plus or a minus…. I'd guess that the crossed drooped dipole or quad helix or quad spirals might have a more consistent phase center as a function of look angle. And a bigger radome is always good, because crud on the radome is farther away and will have less effect. Hi Bob, Many of the midrange antennas have one or more significant differences from the cheap pucks. Firstly they generally have better filtering, many pucks have none. This is important if you are co-located with transmitters. Yes. We have some timing type antennas at work which are effectively jammed by a cellphone near by. And, the geodetic GPS folks are not looking forward to wider deployment of LTE/4G, which uses bands closer to the GPS bands (presumably the 1700 MHz ones), although keeping the phones 10 meters or so away seems to be enough to fix that (barring Light Cubed rising from the dead carcass of Light Squared) Secondly many use quad-helix antenna elements rather than the off-set feed ceramic patches in the pucks. The heical elements have better control of the radiation pattern and along with a larger radome are less likely to be affected by external contamination. I also wonder how the tuning of a cheap ceramic patch holds up over the range of temperatures seen by a fixed antenna. Modern receivers compensate well for poor antennas, try using an early receiver on an internal patch and you won't get great results. You might be able to design a patch that self compensates.. the antenna gets bigger as temperature goes up, but also moves away from the ground plane AND the effective epsilon gets lower because the material is less dense. In any case, it's a small effect. ALumina has a CTE of 6-8 and Copper is about 17, so the thermal effect of an air dielectric copper antenna might be bigger than a plated onto alumina one. Robert G8RPI. From: Bob Camp li...@rtty.us To: Discussion of precise time and frequency measurement time-nuts@febo.com Sent: Sunday, 15 September 2013, 22:19 Subject: Re: [time-nuts] Req: Decent GPS Antenna Active/Passive Recommendation Hi Worth noting: The mid class antennas are not a lot different electrically than the low end antennas. The main differences are mechanical: 1) You get a much more weather tight housing 2) You get a rational way to mount the antenna 3) There's a connector on it so you can put a good piece of coax on it 4) The housing *may* be more immune to snow / ice buildup and bird nests RDR Electronics on the usual auction site appears to be selling some nice ones at the moment. Bob On Sep 15, 2013, at 4:36 PM, Hal Murray hmur...@megapathdsl.net wrote: j...@westmorelandengineering.com said: Well, I need something that I can put outside, in the weather, with my verticals, and other antennas. I am a Ham radio enthusiast, and I want something I can properly mount and can be an all-weather device and can live happily 'in the farm' so to speak. I split GPS antennas into 3 clumps. At the low cost end are the small mouse or hockey-puck type units, usually with a magnetic mount. They typically come with 10 or 15 feet of thin (lossy) cable. Ballpark price is $10. In the middle are the typical cones that you see on cell phone stations. The Lucent 26 dB ones are common on eBay. Ballpark price is $50. The same or very similar thing is also available with different brand names. Some of them come with a pipe mounting setup such that the coax and connector is inside the pipe and out of the weather. http://www.megapathdsl.net/~hmurray/time-nuts/Lucent-Antenna.jpg At the top end are the choke ring antennas intended for surveying. They are mostly out of my price range so I haven't looked carefully. -- I haven't seen a GPS antenna without an amplifier, but I haven't been looking. They also include a filter. See the LightSquared flame-wars for a discussion of filters. I think the choke ring antennas usually let L1 and L2 through while most others are L1 only. The other important consideration is the sensitivity of your receiver. Every couple of years a new generation comes out that is a few dB better than the previous ones. (Has anybody seen a Moore's Law type graph?) Modern receivers are sensitive enough to work indoors with a non-fancy antenna, at least most of the time. YMMV etc
