Antenna for cordless phone
in [Design]
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From: Joerg on 17 May 2010 17:22 D Yuniskis wrote: > Hi John, > > John wrote: >> On Sun, 16 May 2010 10:28:24 -0700, D Yuniskis >> <not.going.to.be(a)seen.com> wrote: >>> >>> Sometimes (rarely), on my "evening sabbatical", I carry >>> a cordless phone (NOT a cell phone) with me. This has >>> sufficient range to cover almost the entire "development" >>> (e.g., I can get about half a mile, as the crow flies). >>> >>> *But*, there is one section (0.52 miles? :> ) where I >>> lose reception. >>> >>> I've toyed with the idea of adding an external antenna to >>> the base unit (which currently just sits on a countertop) >>> to try to improve on that. >>> >>> I rescued a "dual band" antenna kit (AllTel) for a cell phone. >>> But, I suspect these operate on a different frequency than >>> my "cordless" (902-928MHz)? (sorry, I know *nothing* about >>> cell phones -- thankfully! :> ) >> >> Contrary to the popular believe antennae do not increase the >> transmitting power. They change the transmitting power from some >> directions into other directions. > > Correct. I'm not expecting to "boost" the Tx power. > But, rather, get it someplace from which it is easier > for me (at the remote end) to pick it up (likewise, > for the base to pick up my *remote* signal!) > >> You probably are not interested in sending signal to the moon so >> rather then wasting that signal change it to the horizontal plane. >> First you must you must establish the horizontal area that you want to >> cover and if your transmitter is at the end of the terrain you may >> design a small Yagi like the type used to receive TV. > > No. Antenna will be located in almost the exact center of the > area to be covered. I.e., "walking around the neighborhood" > (my "walk" is just about 2 miles total -- the furthest point > being about 0.55 mi from the "base"). > >> You can design an antenna that will give you a pattern like a fig. of >> an heart, a figure of eight or a very directional antenna. The >> directionality will depend on the number of elements. >> Ideally you build 2 antennae of the same type and use one for one unit >> and the other for the other unit. > > The "remote" is a handheld device. Impractical to change the > antenna on it. > >> Coupling to the base unit is another problem. Not easy. >> Describe, please the area you want to cover if you want to make a >> project out of it. I can help. > > The neighborhood is roughly: > > (view in fixed width font) > > +-----+ > | | > | | > | | > | | > | | > | | > | +------------+ > | | > | X | > | | > +------------------+ > > This is *roughly* to scale. The "base" is located at X. > The area is residential in nature so there are houses > filling the region. The top of the illustration is > at a higher elevation than the bottom -- maybe 60 ft? > > There are no commercial establishments in the area. > Most of the construction is masonary. No dense > foliage. > > The problem area (reception) is at the upper left (and > the bottom right) -- no doubt as there are the most > "obstructions" along the sight line. > This almost screams for two directional antennas at the base, yagi or helix. One pointing to the right and the other to the upper left corner. Combined with a splitter (with proper matching in there, of course). If the base has a diplexer you might get away with connecting one to each terminal. Not sure if this is legit though. For a cordless phone setup it probably is not. > I'll drag out a GPS and get some actual measurements, > if necessary. I've not done an exhaustive survey > of where things work/don't work. Though I have found > the upper left corner to be a problem area as I am > often passing through there when I lose signal. > > The antenna that I was *questioning* will (physically) > mate to a Linksys wireless router (though not intended > to do so, "just coincidence" -- sorry, I don't deal with > RF stuff so i can't tell you what sort of connectors > they are -- I don't think they will mate with the > base unit on the phone :<) > Cordless phone on a Linksys router? <scratching head> > This is similar to what the manufacturer suggests for > an external antenna: > > http://www.sn900.com/graphic/extant20.jpg > Better to have two directional ones (if legal). -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: AZ Nomad on 17 May 2010 17:35 On Mon, 17 May 2010 11:25:13 -0700, D Yuniskis <not.going.to.be(a)seen.com> wrote: >Hi TOm, >tm wrote: >> "D Yuniskis" <not.going.to.be(a)seen.com> wrote in message >>>>> I've toyed with the idea of adding an external antenna to >>>>> the base unit (which currently just sits on a countertop) >>>>> to try to improve on that. >>>>> >>>>> I rescued a "dual band" antenna kit (AllTel) for a cell phone. >>>>> But, I suspect these operate on a different frequency than >>>>> my "cordless" (902-928MHz)? (sorry, I know *nothing* about >>>>> cell phones -- thankfully! :> ) >>> No. Antenna will be located in almost the exact center of the >>> area to be covered. I.e., "walking around the neighborhood" >>> (my "walk" is just about 2 miles total -- the furthest point >>> being about 0.55 mi from the "base"). >>> >>>> You can design an antenna that will give you a pattern like a fig. of >>>> an heart, a figure of eight or a very directional antenna. The >>>> directionality will depend on the number of elements. >>>> Ideally you build 2 antennae of the same type and use one for one unit >>>> and the other for the other unit. >>> The "remote" is a handheld device. Impractical to change the >>> antenna on it. >>> >>> The antenna that I was *questioning* will (physically) >>> mate to a Linksys wireless router (though not intended >>> to do so, "just coincidence" -- sorry, I don't deal with >>> RF stuff so i can't tell you what sort of connectors >>> they are -- I don't think they will mate with the >>> base unit on the phone :<) >>> >>> This is similar to what the manufacturer suggests for >>> an external antenna: >>> http://www.sn900.com/graphic/extant20.jpg >> >> Move the base unit to as high a position as possible, maybe into your attic >> if you have one. >No attics here. :-/ I was hoping to run *an* antenna >(on a length of coax) from the base up to a "high(er) spot". >Nervous about the roof due to lightning, etc. Keep in mind that you're likely to lose more power in the cable than any advantage you gain.
From: John on 17 May 2010 19:47 On Mon, 17 May 2010 14:22:42 -0700, Joerg <invalid(a)invalid.invalid> wrote: >D Yuniskis wrote: >> Hi John, >> >> John wrote: >>> On Sun, 16 May 2010 10:28:24 -0700, D Yuniskis >>> <not.going.to.be(a)seen.com> wrote: >>>> >>>> Sometimes (rarely), on my "evening sabbatical", I carry >>>> a cordless phone (NOT a cell phone) with me. This has >>>> sufficient range to cover almost the entire "development" >>>> (e.g., I can get about half a mile, as the crow flies). >>>> >>>> *But*, there is one section (0.52 miles? :> ) where I >>>> lose reception. >>>> >>>> I've toyed with the idea of adding an external antenna to >>>> the base unit (which currently just sits on a countertop) >>>> to try to improve on that. >>>> >>>> I rescued a "dual band" antenna kit (AllTel) for a cell phone. >>>> But, I suspect these operate on a different frequency than >>>> my "cordless" (902-928MHz)? (sorry, I know *nothing* about >>>> cell phones -- thankfully! :> ) >>> >>> Contrary to the popular believe antennae do not increase the >>> transmitting power. They change the transmitting power from some >>> directions into other directions. >> >> Correct. I'm not expecting to "boost" the Tx power. >> But, rather, get it someplace from which it is easier >> for me (at the remote end) to pick it up (likewise, >> for the base to pick up my *remote* signal!) >> >>> You probably are not interested in sending signal to the moon so >>> rather then wasting that signal change it to the horizontal plane. >>> First you must you must establish the horizontal area that you want to >>> cover and if your transmitter is at the end of the terrain you may >>> design a small Yagi like the type used to receive TV. >> >> No. Antenna will be located in almost the exact center of the >> area to be covered. I.e., "walking around the neighborhood" >> (my "walk" is just about 2 miles total -- the furthest point >> being about 0.55 mi from the "base"). >> >>> You can design an antenna that will give you a pattern like a fig. of >>> an heart, a figure of eight or a very directional antenna. The >>> directionality will depend on the number of elements. >>> Ideally you build 2 antennae of the same type and use one for one unit >>> and the other for the other unit. >> >> The "remote" is a handheld device. Impractical to change the >> antenna on it. >> >>> Coupling to the base unit is another problem. Not easy. >>> Describe, please the area you want to cover if you want to make a >>> project out of it. I can help. >> >> The neighborhood is roughly: >> >> (view in fixed width font) >> >> +-----+ >> | | >> | | >> | | >> | | >> | | >> | | >> | +------------+ >> | | >> | X | >> | | >> +------------------+ >> >> This is *roughly* to scale. The "base" is located at X. >> The area is residential in nature so there are houses >> filling the region. The top of the illustration is >> at a higher elevation than the bottom -- maybe 60 ft? >> >> There are no commercial establishments in the area. >> Most of the construction is masonary. No dense >> foliage. >> >> The problem area (reception) is at the upper left (and >> the bottom right) -- no doubt as there are the most >> "obstructions" along the sight line. >> > >This almost screams for two directional antennas at the base, yagi or >helix. One pointing to the right and the other to the upper left corner. >Combined with a splitter (with proper matching in there, of course). If >the base has a diplexer you might get away with connecting one to each >terminal. > >Not sure if this is legit though. For a cordless phone setup it probably >is not. > > >> I'll drag out a GPS and get some actual measurements, >> if necessary. I've not done an exhaustive survey >> of where things work/don't work. Though I have found >> the upper left corner to be a problem area as I am >> often passing through there when I lose signal. >> >> The antenna that I was *questioning* will (physically) >> mate to a Linksys wireless router (though not intended >> to do so, "just coincidence" -- sorry, I don't deal with >> RF stuff so i can't tell you what sort of connectors >> they are -- I don't think they will mate with the >> base unit on the phone :<) >> > >Cordless phone on a Linksys router? > ><scratching head> > > >> This is similar to what the manufacturer suggests for >> an external antenna: >> >> http://www.sn900.com/graphic/extant20.jpg >> > >Better to have two directional ones (if legal). Remember that you are transmitting/receiving to and from an area not to 2 fixed locations. The polarization must be vertical, the same as the mobile unit. If that was my job I would build a dipole with 2 directors, one in each side and , place the receiver/transmitter as close as possible to the antenna but this should be optimized by using test equipment to do the proper matching or at list measure the impedance of the assembly and/or the VSWR. Too elaborate, let's be practical Just try the vertical whip installed as elevated as possible outside the house and with the main unit as close as possible to the antenna John
From: Joerg on 17 May 2010 20:00 John wrote: > On Mon, 17 May 2010 14:22:42 -0700, Joerg <invalid(a)invalid.invalid> > wrote: > >> D Yuniskis wrote: >>> Hi John, >>> >>> John wrote: >>>> On Sun, 16 May 2010 10:28:24 -0700, D Yuniskis >>>> <not.going.to.be(a)seen.com> wrote: >>>>> Sometimes (rarely), on my "evening sabbatical", I carry >>>>> a cordless phone (NOT a cell phone) with me. This has >>>>> sufficient range to cover almost the entire "development" >>>>> (e.g., I can get about half a mile, as the crow flies). >>>>> >>>>> *But*, there is one section (0.52 miles? :> ) where I >>>>> lose reception. >>>>> >>>>> I've toyed with the idea of adding an external antenna to >>>>> the base unit (which currently just sits on a countertop) >>>>> to try to improve on that. >>>>> >>>>> I rescued a "dual band" antenna kit (AllTel) for a cell phone. >>>>> But, I suspect these operate on a different frequency than >>>>> my "cordless" (902-928MHz)? (sorry, I know *nothing* about >>>>> cell phones -- thankfully! :> ) >>>> Contrary to the popular believe antennae do not increase the >>>> transmitting power. They change the transmitting power from some >>>> directions into other directions. >>> Correct. I'm not expecting to "boost" the Tx power. >>> But, rather, get it someplace from which it is easier >>> for me (at the remote end) to pick it up (likewise, >>> for the base to pick up my *remote* signal!) >>> >>>> You probably are not interested in sending signal to the moon so >>>> rather then wasting that signal change it to the horizontal plane. >>>> First you must you must establish the horizontal area that you want to >>>> cover and if your transmitter is at the end of the terrain you may >>>> design a small Yagi like the type used to receive TV. >>> No. Antenna will be located in almost the exact center of the >>> area to be covered. I.e., "walking around the neighborhood" >>> (my "walk" is just about 2 miles total -- the furthest point >>> being about 0.55 mi from the "base"). >>> >>>> You can design an antenna that will give you a pattern like a fig. of >>>> an heart, a figure of eight or a very directional antenna. The >>>> directionality will depend on the number of elements. >>>> Ideally you build 2 antennae of the same type and use one for one unit >>>> and the other for the other unit. >>> The "remote" is a handheld device. Impractical to change the >>> antenna on it. >>> >>>> Coupling to the base unit is another problem. Not easy. >>>> Describe, please the area you want to cover if you want to make a >>>> project out of it. I can help. >>> The neighborhood is roughly: >>> >>> (view in fixed width font) >>> >>> +-----+ >>> | | >>> | | >>> | | >>> | | >>> | | >>> | | >>> | +------------+ >>> | | >>> | X | >>> | | >>> +------------------+ >>> >>> This is *roughly* to scale. The "base" is located at X. >>> The area is residential in nature so there are houses >>> filling the region. The top of the illustration is >>> at a higher elevation than the bottom -- maybe 60 ft? >>> >>> There are no commercial establishments in the area. >>> Most of the construction is masonary. No dense >>> foliage. >>> >>> The problem area (reception) is at the upper left (and >>> the bottom right) -- no doubt as there are the most >>> "obstructions" along the sight line. >>> >> This almost screams for two directional antennas at the base, yagi or >> helix. One pointing to the right and the other to the upper left corner. >> Combined with a splitter (with proper matching in there, of course). If >> the base has a diplexer you might get away with connecting one to each >> terminal. >> >> Not sure if this is legit though. For a cordless phone setup it probably >> is not. >> >> >>> I'll drag out a GPS and get some actual measurements, >>> if necessary. I've not done an exhaustive survey >>> of where things work/don't work. Though I have found >>> the upper left corner to be a problem area as I am >>> often passing through there when I lose signal. >>> >>> The antenna that I was *questioning* will (physically) >>> mate to a Linksys wireless router (though not intended >>> to do so, "just coincidence" -- sorry, I don't deal with >>> RF stuff so i can't tell you what sort of connectors >>> they are -- I don't think they will mate with the >>> base unit on the phone :<) >>> >> Cordless phone on a Linksys router? >> >> <scratching head> >> >> >>> This is similar to what the manufacturer suggests for >>> an external antenna: >>> >>> http://www.sn900.com/graphic/extant20.jpg >>> >> Better to have two directional ones (if legal). > > > Remember that you are transmitting/receiving to and from an area not > to 2 fixed locations. > > The polarization must be vertical, the same as the mobile unit. > > If that was my job I would build a dipole with 2 directors, one in > each side and , place the receiver/transmitter as close as possible to > the antenna but this should be optimized by using test equipment to do > the proper matching or at list measure the impedance of the assembly > and/or the VSWR. Too elaborate, let's be practical > > Just try the vertical whip installed as elevated as possible outside > the house and with the main unit as close as possible to the antenna > Cordless phones aren't strictly vertical anymore, most don't even have as much as a stub for an antenna. Just traces on the board or some wire. When I took apart our previous ones after they were failing I was amazed, they had two antennas diplexed in the handsets. I think Don doesn't want an antenna on the roof so a yagi or something else directional may be his only option in order to get another 5-10dB. But I believe that the base will lose its FCC registration if you do that. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
From: mpm on 17 May 2010 21:45
On May 17, 8:46 am, D Yuniskis <not.going.to...(a)seen.com> wrote: > Hi Joe, > > Joe G (Home) wrote: > >> *But*, there is one section (0.52 miles? :> ) where I lose reception. > > >> But, I suspect these operate on a different frequency than > >> my "cordless" (902-928MHz)? (sorry, I know *nothing* about > >> cell phones -- thankfully! :> ) > > > In the tests we did on a farm - we found the the problem was lack of "line > > of sight" between the base and handset antenna. > > > If you duck behind the metal shed or building was the problem. > > This is an "industrial cordless" -- intended for long range, etc > (600mW Tx). I can get ~0.5 mi *obstructed* connections but getting > much further than that (an extra block or two) is the problem. > I am hoping that getting an antenna "outside" -- or at least > "off the kitchen counter" -- will give me that little bit extra > that is needed. How much attenuation do you think the building is providing? 10dB? 12dB? more? Putting the base on the roof should improve the range, though that is not practical. If you do try to hack in your own DIY antenna, this would violate FCC Rules. (not that people don't do it all the time!) But if it ever ends up causing interference, you could be subject to fines. Plus, you don't really want to interfere in the first place. And, it wouldn't even be easy to do. You would probably have to add amplifiers and filters to get it to work. Messy, expensive, etc... Also, it sounds like you're not sure if signal strength is even the problem (though I agree it sounds like it is). It "could be" localized interference at the two points in question. That's just a guess, BTW. More likely, you've just run out of talk range. That said, you don't which end you've run out on (talk-out from base, or talk-in from handset). At 900 MHz, you might be able to try some aluminum foil around the handset antenna to act like a corner reflector back to the base. You might even be able to cobble something up that does not require you to modify the handset.(?) I wouldn't expect too much performance improvement, (maybe a few dB), but that might be enough if the winds blow just right... :) Good luck! -mpm |