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Re: [BCD396XT] Re: Indoor Antenna

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  • Lance Star
    If you listenin to fire and police dispatch channels that are repeater based, then its not going to matter. But if you want to hear simplex, tactical coms,
    Message 1 of 12 , Jan 31, 2011
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      If you listenin to fire and police dispatch channels that are repeater based, then its not
      going to matter. But if you want to hear simplex, tactical coms, well then, you want a better
      ear of an antenna...

      ----- Original Message -----
      From: "thestreetdisciples" <canadawalrus@...>
      To: BCD396XT@yahoogroups.com
      Date: Tue, 01 Feb 2011 01:15:11 -0000
      Subject: [BCD396XT] Re: Indoor Antenna

      >
      > It is a high rf area as I am downtown of a half million population city in London Ontario Canada.
      >
      > --- In BCD396XT@yahoogroups.com, "johnstark" <johnstark@...> wrote:
      > >
      > > thats a loaded question....load with lots of questions and possible answers.
      > > Theres a lot that needs to be considered, such as if it's high or low RF
      > > area and so forth.
      > >
      > > John
      > >
      > >
      > > ----- Original Message -----
      > > From: "thestreetdisciples" <canadawalrus@...>
      > > To: <BCD396XT@yahoogroups.com>
      > > Sent: Monday, January 31, 2011 7:32 PM
      > > Subject: [BCD396XT] Indoor Antenna
      > >
      > >
      > > > this may be a stupid question but, I live in an apartment with no balcony
      > > > and i am wondering if a magmount antenna on the fridge would pick up more
      > > > than just the normal antenna and if so is there much difference. I
      > > > appreciate all your expertise
      > > >
      > > > Thanks
      > > >
      > > > Steve
      > > >
      > > > canadawalrus@...
      > > >
      > > >
      > > >
      > > > ------------------------------------
      > > >
      > > > Yahoo! Groups Links
      > > >
      > > >
      > > >
      > > >
      > >
      >
      >
      >
    • Michael Hopkins
      Why not ?? should work fine for most local stuff, but any signals coming in from a higher angle could be significantly reduced (air traffic, for example)
      Message 2 of 12 , Feb 1, 2011
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        Why not ?? should work fine for most local stuff, but any signals coming in from a higher angle could be significantly reduced (air traffic, for example) because the antenna’s major radiating (and receiving) pattern will be slightly below the horizon and your air duct would block some of that. Most aircraft have antennas mounted on the bottom of the fuselage so they radiate best down and out; antennas at the airfield and other locations have them pointed up so the radiation is up and away.



        Hope that helps. --- (Can you get the antenna on TOP of the ceiling someplace??)









        Michael



        From: BCD396XT@yahoogroups.com [mailto:BCD396XT@yahoogroups.com] On Behalf Of robdutka@...
        Sent: Monday, January 31, 2011 8:39 PM
        To: BCD396XT@yahoogroups.com
        Subject: Re: [BCD396XT] Indoor Antenna







        Another idea.... I used a magnetic mount to the ceiling air duct right in front of the window and have the antenna hang upside down. Looks funny, but it works.

        I'm not a RF guy so this might not be the best solution, but it works better than the small antenna on the scanner.

        ----- Original Message -----
        From: "thestreetdisciples" <canadawalrus@... <mailto:canadawalrus%40gmail.com> >
        To: BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com>
        Sent: Monday, January 31, 2011 6:32:09 PM
        Subject: [BCD396XT] Indoor Antenna



        this may be a stupid question but, I live in an apartment with no balcony and i am wondering if a magmount antenna on the fridge would pick up more than just the normal antenna and if so is there much difference. I appreciate all your expertise

        Thanks

        Steve

        canadawalrus@... <mailto:canadawalrus%40gmail.com>

        [Non-text portions of this message have been removed]





        [Non-text portions of this message have been removed]
      • Lance Star
        because the antenna’s major radiating (and receiving) pattern will be slightly below the horizon and your air duct would block some of that. He is not
        Message 3 of 12 , Feb 1, 2011
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          "because the antenna’s major radiating (and receiving) pattern will be slightly below the horizon and your air duct would block some of that."

          He is not transmitting here in this case...



          ----- Original Message -----
          From: "Michael Hopkins" <mhopkins735@...>
          To: <BCD396XT@yahoogroups.com>
          Date: Tue, 1 Feb 2011 06:56:53 -0500
          Subject: RE: [BCD396XT] Indoor Antenna

          >
          > Why not ?? should work fine for most local stuff, but any signals coming in from a higher angle could be significantly reduced (air traffic, for example) because the antenna’s major radiating (and receiving) pattern will be slightly below the horizon and your air duct would block some of that. Most aircraft have antennas mounted on the bottom of the fuselage so they radiate best down and out; antennas at the airfield and other locations have them pointed up so the radiation is up and away.
          >
          > Hope that helps. --- (Can you get the antenna on TOP of the ceiling someplace??)
          >
          > Michael
          >
          > From: BCD396XT@yahoogroups.com [mailto:BCD396XT@yahoogroups.com] On Behalf Of robdutka@...
          > Sent: Monday, January 31, 2011 8:39 PM
          > To: BCD396XT@yahoogroups.com
          > Subject: Re: [BCD396XT] Indoor Antenna
          >
          > Another idea.... I used a magnetic mount to the ceiling air duct right in front of the window and have the antenna hang upside down. Looks funny, but it works.
          >
          > I'm not a RF guy so this might not be the best solution, but it works better than the small antenna on the scanner.
          >
          > ----- Original Message -----
          > From: "thestreetdisciples" <canadawalrus@... <mailto:canadawalrus%40gmail.com> >
          > To: BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com>
          > Sent: Monday, January 31, 2011 6:32:09 PM
          > Subject: [BCD396XT] Indoor Antenna
          >
          > this may be a stupid question but, I live in an apartment with no balcony and i am wondering if a magmount antenna on the fridge would pick up more than just the normal antenna and if so is there much difference. I appreciate all your expertise
          >
          > Thanks
          >
          > Steve
          >
          > canadawalrus@... <mailto:canadawalrus%40gmail.com>
          >
          > [Non-text portions of this message have been removed]
          >
          > [Non-text portions of this message have been removed]
          >
          >
          >
        • Michael Hopkins
          Yeah, but transmitting and receiving patterns are typically reciprocal --- a directional transmitting antenna will also be a directional receiving antenna….
          Message 4 of 12 , Feb 1, 2011
          • 0 Attachment
            Yeah, but transmitting and receiving patterns are typically reciprocal --- a directional transmitting antenna will also be a directional receiving antenna…. Some metal in the way of a transmitting signal is also in the way with a signal coming in to be received…





            Michael



            From: BCD396XT@yahoogroups.com [mailto:BCD396XT@yahoogroups.com] On Behalf Of Lance Star
            Sent: Tuesday, February 01, 2011 12:23 PM
            To: BCD396XT@yahoogroups.com
            Subject: RE: [BCD396XT] Indoor Antenna





            "because the antenna’s major radiating (and receiving) pattern will be slightly below the horizon and your air duct would block some of that."

            He is not transmitting here in this case...

            ----- Original Message -----
            From: "Michael Hopkins" <mhopkins735@... <mailto:mhopkins735%40charter.net> >
            To: <BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> >
            Date: Tue, 1 Feb 2011 06:56:53 -0500
            Subject: RE: [BCD396XT] Indoor Antenna

            >
            > Why not ?? should work fine for most local stuff, but any signals coming in from a higher angle could be significantly reduced (air traffic, for example) because the antenna’s major radiating (and receiving) pattern will be slightly below the horizon and your air duct would block some of that. Most aircraft have antennas mounted on the bottom of the fuselage so they radiate best down and out; antennas at the airfield and other locations have them pointed up so the radiation is up and away.
            >
            > Hope that helps. --- (Can you get the antenna on TOP of the ceiling someplace??)
            >
            > Michael
            >
            > From: BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> [mailto:BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> ] On Behalf Of robdutka@... <mailto:robdutka%40comcast.net>
            > Sent: Monday, January 31, 2011 8:39 PM
            > To: BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com>
            > Subject: Re: [BCD396XT] Indoor Antenna
            >
            > Another idea.... I used a magnetic mount to the ceiling air duct right in front of the window and have the antenna hang upside down. Looks funny, but it works.
            >
            > I'm not a RF guy so this might not be the best solution, but it works better than the small antenna on the scanner.
            >
            > ----- Original Message -----
            > From: "thestreetdisciples" <canadawalrus@... <mailto:canadawalrus%40gmail.com> <mailto:canadawalrus%40gmail.com> >
            > To: BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> <mailto:BCD396XT%40yahoogroups.com>
            > Sent: Monday, January 31, 2011 6:32:09 PM
            > Subject: [BCD396XT] Indoor Antenna
            >
            > this may be a stupid question but, I live in an apartment with no balcony and i am wondering if a magmount antenna on the fridge would pick up more than just the normal antenna and if so is there much difference. I appreciate all your expertise
            >
            > Thanks
            >
            > Steve
            >
            > canadawalrus@... <mailto:canadawalrus%40gmail.com> <mailto:canadawalrus%40gmail.com>
            >
            > [Non-text portions of this message have been removed]
            >
            > [Non-text portions of this message have been removed]
            >
            >
            >





            [Non-text portions of this message have been removed]
          • Lance Star
            If that was the case then I would not be able to recieve signals from a yagi antenna using a omni-directional antenna... In the same light, a Southwest Jet
            Message 5 of 12 , Feb 1, 2011
            • 0 Attachment
              If that was the case then I would not be able to recieve signals from a yagi antenna using a omni-directional antenna...

              In the same light, a Southwest Jet flying at Flight Level 430 transmitting from the lower dorsal fin antenna to my handheld with a
              vertically upright oriented antenna would not recieve signals based on theory of reciprocal...

              I think for this person he needs more surface area to recieve signals if "line of site" , "point to point" simplex coms is what he is interested in.

              If he was just listening to police/fire/ambulance dispatch that would not take much of an antenna with repeater TX power being 50-100 watts
              not to mention the ERP when one adds the gain of the antenna. In some cases that could be up around 12 dB or more.

              I can recieve San Francisco PS Trunk System with a bnc stub antenna (about 1/4") long, used for Indy Races as an example.

              At least our friend has a frige to act as a groundplane. Although Mag mount antennas are capacitively coupled...







              ----- Original Message -----
              From: "Michael Hopkins" <mhopkins735@...>
              To: <BCD396XT@yahoogroups.com>
              Date: Tue, 1 Feb 2011 14:01:13 -0500
              Subject: RE: [BCD396XT] Indoor Antenna

              >
              > Yeah, but transmitting and receiving patterns are typically reciprocal --- a directional transmitting antenna will also be a directional receiving antenna…. Some metal in the way of a transmitting signal is also in the way with a signal coming in to be received…
              >
              > Michael
              >
              > From: BCD396XT@yahoogroups.com [mailto:BCD396XT@yahoogroups.com] On Behalf Of Lance Star
              > Sent: Tuesday, February 01, 2011 12:23 PM
              > To: BCD396XT@yahoogroups.com
              > Subject: RE: [BCD396XT] Indoor Antenna
              >
              > "because the antenna’s major radiating (and receiving) pattern will be slightly below the horizon and your air duct would block some of that."
              >
              > He is not transmitting here in this case...
              >
              > ----- Original Message -----
              > From: "Michael Hopkins" <mhopkins735@... <mailto:mhopkins735%40charter.net> >
              > To: <BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> >
              > Date: Tue, 1 Feb 2011 06:56:53 -0500
              > Subject: RE: [BCD396XT] Indoor Antenna
              >
              > >
              > > Why not ?? should work fine for most local stuff, but any signals coming in from a higher angle could be significantly reduced (air traffic, for example) because the antenna’s major radiating (and receiving) pattern will be slightly below the horizon and your air duct would block some of that. Most aircraft have antennas mounted on the bottom of the fuselage so they radiate best down and out; antennas at the airfield and other locations have them pointed up so the radiation is up and away.
              > >
              > > Hope that helps. --- (Can you get the antenna on TOP of the ceiling someplace??)
              > >
              > > Michael
              > >
              > > From: BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> [mailto:BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> ] On Behalf Of robdutka@... <mailto:robdutka%40comcast.net>
              > > Sent: Monday, January 31, 2011 8:39 PM
              > > To: BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com>
              > > Subject: Re: [BCD396XT] Indoor Antenna
              > >
              > > Another idea.... I used a magnetic mount to the ceiling air duct right in front of the window and have the antenna hang upside down. Looks funny, but it works.
              > >
              > > I'm not a RF guy so this might not be the best solution, but it works better than the small antenna on the scanner.
              > >
              > > ----- Original Message -----
              > > From: "thestreetdisciples" <canadawalrus@... <mailto:canadawalrus%40gmail.com> <mailto:canadawalrus%40gmail.com> >
              > > To: BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> <mailto:BCD396XT%40yahoogroups.com>
              > > Sent: Monday, January 31, 2011 6:32:09 PM
              > > Subject: [BCD396XT] Indoor Antenna
              > >
              > > this may be a stupid question but, I live in an apartment with no balcony and i am wondering if a magmount antenna on the fridge would pick up more than just the normal antenna and if so is there much difference. I appreciate all your expertise
              > >
              > > Thanks
              > >
              > > Steve
              > >
              > > canadawalrus@... <mailto:canadawalrus%40gmail.com> <mailto:canadawalrus%40gmail.com>
              > >
              > > [Non-text portions of this message have been removed]
              > >
              > > [Non-text portions of this message have been removed]
              > >
              > >
              > >
              >
              > [Non-text portions of this message have been removed]
              >
              >
              >
            • Alex
              No antenna (except for a dish and not quite that even) is perfectly directional. There are lobes all around every type of antenna including a Yagi-Uda, log
              Message 6 of 12 , Feb 2, 2011
              • 0 Attachment
                No antenna (except for a dish and not quite that even) is perfectly directional. There are lobes all around every type of antenna including a Yagi-Uda, log periodic or any other form of multi-element antenna. The key factor is that the gain of the antenna is focused in one direction if it's a directed antenna (such as a Yagi) and uniform if it's some type of vertical antenna. Directed gain does not preclude you receiving signals from one type of antenna to another, it just determines how much signal you get. The radiation pattern of the antenna is not determined by transmit or receive but its construction so the statement that it is reciprocal is accurate. The gain envelope will be the same no matter what purpose the antenna is used. The total gain envelope of the antenna is constant it's just where all that gain is pointed. A Yagi has a lot of gain in one direction and not much in most others while an omni has a little gain in all directions.

                In the case of the plane, the dorsal antenna is not a Yagi, it's a short vertical antenna (not quite omni). The fuselage of the plane is actually causing a reflection, too, so that the main gain lobes of the antenna aren't pointing at the horizon anymore, they are actually tilted away from the fuselage by a small amount (at most frequencies it works out to about a 15 degree tilt). There is signal still spilling out in various other directions but the vast majority of the signal is pointed in the general direction of the ground but uniformly. There's no sense wasting transmit power by sending it skyward where there aren't any airports to listen.

                Believe it or not, your vertical antenna is not completely omnidirectional. It's actually mostly directional out the side of the antenna perpendicular to its axis . The gain pattern of a vertical antenna is approximately a torus (a donut). There is a bit of signal leakage along the axis of the antenna but not much. This is approximately the same pattern as the antenna on the plane. However, the torus is pretty thick on a stubby antenna like that used on a handheld scanner so there's a lot of skyward and groundward gain lobe, too. That makes it *nearly* omnidirectional but not quite. This is a feature of verticals sometimes used to do signal tracking if you can't get a Yagi.


                As it was always said in my RF engineering classes, antennas are a black art. Something will work in one place and doesn't in another due to very complex interactions. There's a reason that companies like Sonnet and others sell RF modeling software for thousands of dollars because it's not easy to predict everything.

                Antennas have key features that help. The size of the antenna determines it's signal cross section (or electrical cross section for some modified versions). You want as much cross section as possible to pick up all the signal you can. This works in the reciprocal, too, because you want a large antenna for large transmit signal, too. Stubby antennas use coiled wire to achieve more electrical length for less physical length. This does work to some extent though there's a slight efficiency/gain penalty for doing so. Height determines range which is also influenced by the gain pattern. You can have all the height you want but if the signal of interest is inside a low-gain lobe of the antenna, it won't help as much. Directionality has already been discussed but the basic idea is to have all the gain possible in the direction of the signals of interest. For most scanning, an omni is the required choice because the signals are coming from everywhere. However, if I were out at sea wanting to listen to all the signals on the coastal city, I would choose a Yagi or a dish antenna instead otherwise I waste my antenna gain with an omni.



                --- In BCD396XT@yahoogroups.com, Lance Star <milcom_chaser@...> wrote:
                >
                > If that was the case then I would not be able to recieve signals from a yagi antenna using a omni-directional antenna...
                >
                > In the same light, a Southwest Jet flying at Flight Level 430 transmitting from the lower dorsal fin antenna to my handheld with a
                > vertically upright oriented antenna would not recieve signals based on theory of reciprocal...
                >
                > I think for this person he needs more surface area to recieve signals if "line of site" , "point to point" simplex coms is what he is interested in.
                >
                > If he was just listening to police/fire/ambulance dispatch that would not take much of an antenna with repeater TX power being 50-100 watts
                > not to mention the ERP when one adds the gain of the antenna. In some cases that could be up around 12 dB or more.
                >
                > I can recieve San Francisco PS Trunk System with a bnc stub antenna (about 1/4") long, used for Indy Races as an example.
                >
                > At least our friend has a frige to act as a groundplane. Although Mag mount antennas are capacitively coupled...
                >
                >
                >
                >
                >
                >
                >
                > ----- Original Message -----
                > From: "Michael Hopkins" <mhopkins735@...>
                > To: <BCD396XT@yahoogroups.com>
                > Date: Tue, 1 Feb 2011 14:01:13 -0500
                > Subject: RE: [BCD396XT] Indoor Antenna
                >
                > >
                > > Yeah, but transmitting and receiving patterns are typically reciprocal --- a directional transmitting antenna will also be a directional receiving antenna…. Some metal in the way of a transmitting signal is also in the way with a signal coming in to be received…
                > >
                > > Michael
                > >
                > > From: BCD396XT@yahoogroups.com [mailto:BCD396XT@yahoogroups.com] On Behalf Of Lance Star
                > > Sent: Tuesday, February 01, 2011 12:23 PM
                > > To: BCD396XT@yahoogroups.com
                > > Subject: RE: [BCD396XT] Indoor Antenna
                > >
                > > "because the antenna’s major radiating (and receiving) pattern will be slightly below the horizon and your air duct would block some of that."
                > >
                > > He is not transmitting here in this case...
                > >
                > > ----- Original Message -----
                > > From: "Michael Hopkins" <mhopkins735@... <mailto:mhopkins735%40charter.net> >
                > > To: <BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> >
                > > Date: Tue, 1 Feb 2011 06:56:53 -0500
                > > Subject: RE: [BCD396XT] Indoor Antenna
                > >
                > > >
                > > > Why not ?? should work fine for most local stuff, but any signals coming in from a higher angle could be significantly reduced (air traffic, for example) because the antenna’s major radiating (and receiving) pattern will be slightly below the horizon and your air duct would block some of that. Most aircraft have antennas mounted on the bottom of the fuselage so they radiate best down and out; antennas at the airfield and other locations have them pointed up so the radiation is up and away.
                > > >
                > > > Hope that helps. --- (Can you get the antenna on TOP of the ceiling someplace??)
                > > >
                > > > Michael
                > > >
                > > > From: BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> [mailto:BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> ] On Behalf Of robdutka@... <mailto:robdutka%40comcast.net>
                > > > Sent: Monday, January 31, 2011 8:39 PM
                > > > To: BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com>
                > > > Subject: Re: [BCD396XT] Indoor Antenna
                > > >
                > > > Another idea.... I used a magnetic mount to the ceiling air duct right in front of the window and have the antenna hang upside down. Looks funny, but it works.
                > > >
                > > > I'm not a RF guy so this might not be the best solution, but it works better than the small antenna on the scanner.
                > > >
                > > > ----- Original Message -----
                > > > From: "thestreetdisciples" <canadawalrus@... <mailto:canadawalrus%40gmail.com> <mailto:canadawalrus%40gmail.com> >
                > > > To: BCD396XT@yahoogroups.com <mailto:BCD396XT%40yahoogroups.com> <mailto:BCD396XT%40yahoogroups.com>
                > > > Sent: Monday, January 31, 2011 6:32:09 PM
                > > > Subject: [BCD396XT] Indoor Antenna
                > > >
                > > > this may be a stupid question but, I live in an apartment with no balcony and i am wondering if a magmount antenna on the fridge would pick up more than just the normal antenna and if so is there much difference. I appreciate all your expertise
                > > >
                > > > Thanks
                > > >
                > > > Steve
                > > >
                > > > canadawalrus@... <mailto:canadawalrus%40gmail.com> <mailto:canadawalrus%40gmail.com>
                > > >
                > > > [Non-text portions of this message have been removed]
                > > >
                > > > [Non-text portions of this message have been removed]
                > > >
                > > >
                > > >
                > >
                > > [Non-text portions of this message have been removed]
                > >
                > >
                > >
                >
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