Antenas: Can you connect an antena by induction?

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herod
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Antenas: Can you connect an antena by induction?

Post by herod » Wed Nov 05, 2003 6:14 am

Hello, new to this forum. A lot of knowledgable people hear. <p>I work in an office with a window, I have a boom box within a foot of the window which has metal shades, always open. The boom box, a Phillips CD player, stays most of the time on FM where I can get a couple of talk radio stations. One of the stations, which I get fine in my truck, is mostly just hiss with broken program content which is unintellable. The window roughly faces the station locations to the north. My question is can you put an outside FM antena of some sort and connect it to the radio whip antena with a coil of some sort? And of course how do you do this. There are no external antenna connections or I would use them. Or where do I connect an antenna internally if I can't induct a connection?<p>Thanks in advance, Wade
Wade in Florida

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Re: Antenas: Can you connect an antena by induction?

Post by k7elp60 » Wed Nov 05, 2003 6:57 am

Here is an idea that may work for you. Put your outside FM antenna where you want. Use an indoor outdoor 300 ohm to 75 ohm matching transformer on the antenna. Run the coax indoor to the location of the boombox. One the end of the coax make a two or three turn loop of wire around the boombox antenna, that this connected to the end of the coax.
:) Ned

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Edd
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Re: Antenas: Can you connect an antena by induction?

Post by Edd » Wed Nov 05, 2003 5:06 pm

Wade:
Seems like Ned aptly covered you if an external ant is involved. As well , inductive or foil capacitive tab coupling of the RF signal thru the window glass could also be utilized IF this window is one that doesn’t open or there is a masonry wall that one would have to drill for wire passage. Also, naturally, none of that being practical, if you’re up over 1+ story due to external accessibility to the outside of that sealed window.
Since you have tried the receiver against that station side wall with its whip, you are already up at a 1 story +? height advantage over the auto. The auto receiver typically would have an advantage in its front end electronics due to the more challenging reception conditions a mobile unit would tend to encounter. What you might try to do at that site is take the receiver out in the open, or an open balcony? (if any tenant has such) or from the rooftop. This being basically to see if this particular units front end will pull in reception from this location on that/other desired station(s). Now if the buildings skin is metal, you know that you are knocked by shielding right there. Move on to brick, no/or minor RF shielding there, wood frame construction… even better. Stucco construction…..reception negated by the sheets of metal lath used underneath in bonding. Lastly there’s usually one factor always overlooked , namely , the widespread use of alum foil faced batting insulation as well as on the foam and polyiso family insul sheeting .This really started strong after the ’72 energy crunch time frame and on construction upgrades after that. So, the latter factor then seriously degrades rabbit ear TV or whip FM radio reception, now even in a brick or wood framed edifice….also even portable 900meg and 2.1 gig phone units with their low/short whip antennas when trying to reach outward from the bldg.
With any/all of those unsuspected variables potentially working against you, and you knowing by an adjacent site evaluation that reception is possible, the crudest , yet simplest might be to extend a length of insul hookup wire to the window…considering that exit from the window/frame/wall might be made thru a 1/16 in hole and dangle down
about 60 in for mid-band FM with the inside end connecting to the whip ant. If that is inadequate the next upgrade would be to a common folded dipole ant made with 300 ohm twinlead that typically comes with component system receivers or from Rad Shack off the peg board. That would be taped hoz inside the window frame , getting a shot centered thru a shutter slot, with the dipole ends folded down vertically if this is not a wiiiide window. Terminate the out[put end into a 300-75 balun, as mentioned before . Its center pin would be the sig in to the whip and the balun shell gnd would be wired to a chassis gnd of the rec ; typically a wire to the batt packs neg terminal would be the same.<p> 73's de Edd
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jollyrgr
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Re: Antenas: Can you connect an antena by induction?

Post by jollyrgr » Fri Nov 07, 2003 7:17 am

You did not say what floor your office is on or if you can open the window or not. If you can get to the outside of the window (and your employer does not mind) you could install a "GLASS MOUNT" scanner antenna. See this example from Radio Shack:<p>http://www.radioshack.com/product.asp?catalog%5Fn ame=CTLG&category%5Fname=CTLG%5F008%5F009%5F010%5F001&product%5Fid=20%2D011<p>Place the antenna on the window per the directions supplied. Take the BNC connector and connect it to the radio's telescoping whip. You might need some sort of adapter such as a Female BNC to Car Radio adapter. Then connect the center conductor to the radio's antenna.<p>Radio Shack also sells a CB antenna that is through the glass. This antenna is about $10 more than the scanner one outlined above. You do not want this antenna for your FM radio.<p>You might want to try the twin lead "dipole" antenna first. These are under $5 and available just about every department store that sells electronic goodies. Simply connect one or both of the wires to the telescope whip and tape the antenna to the window. Experiment with it as you might be able to place it to the side of the window and still get decent results.
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Re: Antenas: Can you connect an antena by induction?

Post by herod » Sat Nov 08, 2003 7:31 am

Sorry I took so long to get back. The window, actually two adjacent windows, are on the 1st floor. I have an old scanner magnetic mount antenna that I can try out. Next time I'm by a Radio shack I'll pick up a dipole to try also. I tried a cell phone magnetic antenna, but that didn't seem to work too well, but I just wrapped the cable around the whip and touch the tip to the whip, no ground. I need to make up the cable, with striped wire and connect a ground. Sometimes living out in the country slows access to shopping for the proper stuff.<p>Thanks for the help.<p> :)
Wade in Florida

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