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Cell phone Booster Antenna

  1. Aug 21, 2004 #1
    Hello all,

    I have this weird idea for a cell phone booster antenna and I thought i would run it past you all here to see if it could work.

    Where I live, we get really bad reception inside our house so I commonly have to step outside and use my cell phone in the driveway to get a decent signal. Just recently, I had a bright idea to replace the short stub of an antenna with a large, homemade one (using a screw and a metal coat hanger). Surprisingly it works great despite its obvious cheapness. However, I had another bright idea. I have another cell phone (which unfortunately doesn't have an antenna that I can replace on it) so if I were to create a big spiral antenna and hang it high up in a tree somewhere and run a wire to another spiral antenna hanging on the wall in my house, would the antenna channel the cell phone signal from outside into my house so I could get a better reception? Then I could just stand in front of the spiral and get a stronger reception. (Well, that’s the thought anyway). Is this in any way possible? If not, could I build some kind of antenna booster circuit to catch the signals coming from the outside antenna, boost them, and then transmit them into the antenna in the house so I can get a better signal? Can you tell I know nothing about radio antennas? :rolleyes:

    I would appreciate any comments/ suggestions on this idea. If it is even vaguely possible to do, could someone give me some pointers?

    Jason O
  2. jcsd
  3. Aug 24, 2004 #2
    Cell phone antennas are as efficient as any for the frequency at which they work ( size per se is not important ) because they are not working in the same way as a dish antenna. However the screening effects of walls , the earth , and so called 'multipath interference' can seriously effect signal strengths , which can vary enormously over distances of inches and feet.
    A simple 'extension wire' may or may not do anything because it is long compared to the wavelength ( 1 ft or less ) , but the idea of using an external antenna which is the connected to ( by some means ) to an internal antenna is valid but rather complex .
    If you have bad reception it is just as likely that you have bad transmission ( the path is reversible ) and you are not allowed to retransmit in this band with home made devices.
    I wonder if there is a way of doing this with two or more phones one mounted in a suitably high place to communicate to the one 'in house' to act as a relay device -- I don't have time to think about it ask a radio Ham they do this type of thing . Ray.
  4. Oct 10, 2010 #3
    Hay. I go to Itt for electronics. If you wanted to do that you need a transiever that would take the existing signals and retransmit them on the same frequency but with a stronger signal. as far as antena's go, that last post was 100% true. at the frequencys that cell phones work on the antenna doesnt need to be all that long. if you got a boost with the coat hanger then that must have been a old phone. thay use to make them so thay used more power to the antenna. hence a longer antenna could still utilize the power. early cell phones used between 0.7 and 3 amps. now thay use somewhere between 0.1and 2 Amps but dont quote me on that. as far as your spiral antenna theory im gonna mess with putting a amplifier in between the two antennas and see how that comes out. Ill let you know when i figure out more.

  5. Oct 10, 2010 #4
    I have one of the first Cingular Motorola V551 phones made, later ones were a bit different. It has a port for an antenna. I went to an electronics specialty place where they ordered an adapter that plugged into the phone and another adapter that allowed that adapter to screw to my old window mounted antenna made for an old analog bag phone. I could be on the road and run out of bars and connectivity, plug it in to this old antenna and in about 20 seconds the phone would have full bar strength. It was wonderful but I've never found another phone that would do that. The people told me that phone had circuitry that allowed it to turn into a 3 watt phone when hooked to the external antenna. It certainly seemed to be that way and I never regretted spending the $20 or so it cost to attach it to that antenna. I would plug it in and drive down the road and notice I never lost signal in several places I didn't have any signal before. I'd like to find another phone just like that since it was a 4 band phone and was armored with a very stubby antenna made from the same stuff the armor was made from. I had to buy a new phone after changing carriers twice in several years and when I was buying a phone at the ATT store, a woman pulled out an old phone like it and even though she was buying all new phones for her family, she wouldn't sell it to me. I should have acted as if I didn't care and she probably would have since she seemed to get excited because I got excited when I saw it and wanted to buy it. I wouldn't doubt she eventually pulled the SIM card out of her new one and put it in that old one.
  6. Oct 11, 2010 #5
    Drop-in cell phones have now become common place enough that we design them in at work. Unfortanately, the antennas are all embedded into the products and are a nightmare to tune and get reasonable performance from.
    They tend to be very high-q affairs constructed from ceramic resonators, or stack PCB resonators, and loading effects due to nearby circuit boards, hands, etc... throw them off. I can see where an external "stick" antenna would outshine what's normally used.
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