FM antenna made simple

I have to agree with Sgmlaw here for the most part. Getting a good outdoor antenna mounted up high with a low loss feedline that is carefully routed is what we should all be striving for. A large Yagi on a rotor would be optimum, but well beyond what most folks require for decent reception. If that's not possible, you may be stuck with one of the indoor antennas or the homebrew that i described. One of the advantages that the design that i mentioned has is that it is vertical rather than horizontal. If you don't think that this makes a difference, take a listen to your car stereo sitting out in front of the house. Chances are, the stock Delco, Ford or Mopar "sound system" with an external body mounted antenna just might be able to pick up stations that your high dollar tuner with great specs and amplified indoor antenna can't seem to pull in. There are two reasons for this. The car antenna and the vertical dipole that i suggest are both omnidirectional whereas many of the amplified antennas and the "T" antennas are cross polarized (both vertical and horizontal) and relatively directional. This means that they are highly susceptible to multi-path and far more sensitive to "aiming". With the vertical dipole, you shouldn't have to fuss with orientation as long as you keep the entire antenna vertical and mount it as i described. If your trying to pick up a specific station but are having a hard time doing it, you can make the vertical dipole somewhat directional by playing with the orientation and direction of the ground (bottom) wire. Another reason that the center fed dipole works well is that the antenna is naturally resonant at the lengths that i mentioned (between 28" and 32"). It therefore offers gain over an "untuned" or "non-resonant" antenna that is of random length or design. One more comment is that sometimes what we attribute to being a poor incoming signal is actually TOO much signal. This can cause front end overload. Signs of this are that the station has a "ragged edge" to it and always sounds like it is not exactly on center channel. While this might sound like the symptoms of a weak or distant station, the difference is that these stations come in quite loud and can be tuned in over a wider frequency range than normal. The signal is so strong that it is actually bleeding over onto adjacent frequencies. This can be caused by being very close to the transmitter or having an amplified antenna system turned up way too much. In some extreme cases, you might even need to install an inline attenuator. This "eats up" some of the signal coming into the tuner, reducing it's strength to a level that the the receiver section can more easily deal with. Keep in mind that if you do have a "mast mounted" amplifier near the antenna, the indoor section of this device MUST be located BEFORE any splitters are put into the system. In other words, you would need to have the outdoor antenna connected to the mast mounted amplifier section, a piece of coax coming down into the house, the control section of the amplifier and then any splitters that were absolutely necessary. Placing a splitter between the mast mounted amp and the control panel could either reduce or absolutely kill the performance of the amplifier, making it useless and sometimes even detrimental to the system. This is often overlooked or not fully understood by inexperienced installers. For those that desire the best performance from their FM systems, you might want to check into the Magnum Dynalabs Signal Sleuth. This acts as both an amplifier and filter and is commonly referred to as a "pre-selector" in the RF field. This makes the signal both stronger and sharper sounding while rejecting outside interference. Hope this helps. Sean >

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Here is a simple approach that works quite well in many installations. It is a "quick and dirty" vertical center fed dipole antenna that should easily outperform the "T" antenna that your using or even one of those fancy $80 antennas from Fanfare or Magnum. I will give you the basics and you can improvise from there. You will need a section of coax to reach from the point of installation, a 60" piece of wire and some clear 2" packing tape. I would recommend using a LONG length of pre-packaged coax so that you can cut it to length as needed once your done. If you can solder, that would be great, otherwise simple wire wrapping will suffice as long as you make a secure connection. First of all, you need to locate a window that you don't mind leaving closed that faces the direction of the majority of broadcasts that your trying to receive. In other words, a window that faces the nearby City in most cases. Once you've done that, you will need to construct the antenna. You can use either insulated or uninsulated wire, either will work. Start off by cutting two 30" sections of wire. You will need to also strip the end of the coax that your going to use and seperate the center ( hot ) wire from the braid ( ground ). You will need about 1" of exposed wire from each of these, but you have to make sure that the hot wire is still insulated from the braid. If you can solder, attach the center wire to one 30" section at the very end and the braid to the other 30" section of wire at it's very end. Do this as neatly and as sturdily as is possible. If you can't solder, simply twist the wires as mentioned above as best possible without breaking them. You can apply a small amount of tape to hold them together and reinforce them, but DON'T count on the tape to make the connection. Now take the entire length of coax and the wire to the point of installation, the window facing the broadcast center. What we are trying to do here is to situate the antenna as high as is possible while still keeping it away from any metal framing that the window or sill might have. In other words, DON'T mount it off to the side or all the way up against the metal framing if at all possible. Running it down the center of the glass in an open area will give best results. Take the wire that is connected to the center section of the coax ( this is the "hot" wire ) and tape it near the very top of the window running vertically. This means that the "free" end of the wire is near the ceiling with the "connected" draping down towards the floor. Once you have the very tip of the vertical antenna reasonably secured, come down it's length and tape just above the connection to the coax. Keep in mind that you want to keep this straight and pulled reasonably tight. Once this is done, take a small piece of tape from the dispenser and place it nearby. Now you need to secure the bottom section of the antenna, commonly referred to as the "ground plane". This should be strung vertically down the window in the same fashion as the "hot" wire was done so that it looks like a straight line. Make sure that the "hot" wire and the "ground plane" are still isolated from each other but don't try to pull them too hard to keep them seperated. Your connections might pull apart and we don't want that. Now secure the "ground plane" just under the coaxial split with that small piece of tape that you previously set aside. Like you did with the top section, stretch the "ground plane" towards the floor as straight as is possible and secure that section at the tip. Once you are satisfied with the basic installation, run a piece of tape vertically on top of the wire the entire length if at all possible. If part of the ground extends below the bottom of the window and down the wall, that is okay. It is best if it is not right by a power outlet though as that means that there is conduit nearby and it might affect the tuning of the antenna. Once this section of the installation is done, it is up to you to route the coax to the tuner. Obviously taking the shortest path is best but as a matter of convenience and practicality, that might not be possible. You might want to try the antenna out BEFORE doing any type of permanent installation, as it would be a bummer to go through all of this without it giving you the performance that you were looking for. Once your sure that it is working to your satisfaction, route the coax as best possible, cut it to length leaving a bit of slack and then install a new "F" connector. This should do the job for you without having to go on the roof for anything. This basic design gives good omnidirectional coverage but could be affected by all of the conduit or aluminum siding on the house if you have it. This could also be installed outside by securing it to the outside of the building or a nearby tree. Don't run the wires vertically along a metal pipe or mast, as that will drastically alter its performance. Should the connection ever break and you need to shorten the antenna section for some reason, the overall length is not real critical. You would want to stay with something between appr. 28" and 32" for both sections though. Having them exactly the same lengths is not necessary, but they should be close. The shorter length of 28" will favor stations higher on the dial while the longer length of 32" wil favor stations lower on the band. If you listen to specific stations on one extreme or the other, you might want to take this into consideration when doing the initial install. Hope this helps someone out. Should you have problems or questions, hit me with an email. Sean
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PS........ Sorry for the novel and some of the wording errors. I hope you got the idea. Sean
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Glad that it is working out a little better for you. The reason that i said to mount it in the window was for specific reasons. If it is mounted in the middle of a window, it is not REAL close to any metal that might detune it plus it is still indoors. This protects the wire from being exposed to the weather and will keep both it and all of the connections from corroding. As mentioned previously, this basic design is omnidirectional, i.e. it should pick up all directions relatively equally as long as the entire antenna is vertical. If you've got aluminum siding, the wooden shudder is near a large metal frame for the window or you have conduit or wiring located closely to the antenna in the wall behind it, this could cause both detuning and directionality. If you can, you might want to run another wire dipole on the west side of your house and then simply hook up an antenna switchbox that you can get from Rat Shack. This would give you the best of both worlds at the flip of a switch. Sean
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