Tips on FM Radio Dipole Antenna Setup?

msg

Hey guys,
I still like to "stream" a little FM radio over the air from time to time, but never really been very good about getting a good signal.

All I'm using for an antenna is a little cheapie FM dipole - one of those T jobs.

Anyone got any placement/setup tips for these things?
Specifically whether best to put near a window, certain clearance from the ceiling, possible interference obstacles, etc.?

Our local public radio puts out a nice strong signal, and I'm using a little B&K TS-108. Various front ends. Sounds really nice with an old Realistic STA-84 receiver with some LSi7 bookshelf speakers, but right now it's running into the main 2ch system over XLR! into the P5.

I have to listen in mono because stereo gets too staticky.

mhardy6647

Your antenna really doesn't care about anything but (RF) grounds in terms of windows, walls, etc. If you're in a building with metal framing (or -- heh -- a metal roof, like ours), you may be in a Faraday Cage, otherwise, interior walls are probably OK -- although the less "stuff" between antenna & signal, the better (of course). Tryin' it in front of a window (or, as I have been known to do, sort of casually and unobtrusively draped along a convenient curtain rod!) is always a good idea if practical.

Get your antenna as high as possible. FM signals essentially follow the "line of sight"; your antenna will "see" a farther away signal when it is higher than when it is lower. I.e., the higher the antenna is, the farther away is its horizon

Remember the reception pattern of a "T" dipole looks like a figure 8. Good sensitivity on either side of the "T", essentially no sensitivity at the "ends" of the "T".

You may get better results with the "T" oriented like the letter "T", or it might be better rotated 90 degrees relative to the printed letter "T"(i.e., sideways, I didn't describe this very well, did I?); try both.

Hope this helps a wee bit

mhardy6647

STA-84. Now, I really (really!) don't mean to besmirch this receiver, but the tuner specs that "The Shack" quoted for it in 1977 are kind of meh.



(2 uV sensitivity and 2 dB capture ratio)

Now, there is no doubt that any improvements in antenna (location or performance) will improve reception for any tuner... but a somewhat "hotter" tuner will (or at least should) do a somewhat better job with any given antenna than that one.

msg

That's the one
Yeah, the tuner doesn't really work well in it. I don't know the first thing about tuner specs or 'tuning' one up. This is why I use the external B&K with it. I also have an older Fisher something or other that I use with another little retro 2ch radio setup. I do like the sound of this old receiver.

msg

That was great info, Doc, thanks. If nothing else, given my lack of visualization of description at times, entertaining lol

I do vaguely remember reading at one point about the drunken T laying in the gutter. I might give that a shot. Which would be better for what leads me to my next question...

Does it make a difference to have the antenna 'body' fully extended? In a conventional T, I would mean to say, with the vertical part stretched out as straight as possible, and not folded or slack, for example, oriented downward from the connection, then looping back up? (Imagine a tuner positioned high up on a shelf instead of low down) I would imagine so, sort of along the lines of fully extending a telescoping antenna?

billbillw

I have always had best luck putting these close to windows, as high as possible. Best results usually if you can orient it perpendicular to the signal source. I have found a few instances where vertical orientation worked better, but that is usually the exception.

mhardy6647

msg wrote: »

That's the one
Yeah, the tuner doesn't really work well in it. I don't know the first thing about tuner specs or 'tuning' one up. This is why I use the external B&K with it. I also have an older Fisher something or other that I use with another little retro 2ch radio setup. I do like the sound of this old receiver.

Oh, sorry, I missed that.

PM me and remind me where-ish in the country you live; I might be able to send you something to try (if the shipping costs aren't too extreme).

mhardy6647

"perpendicular to the signal source" -- yeah, those are the words I was grappling for, billbillw!

By and large, the arms of the "T" should be stretched out (sort of like Frank Zappa's "Nanook of the North" ) -- but don't hesitate to experiment with, say, in the corner placement if convenient & easy to 'beta test'.

One thing to remember, though -- your body will also act as an antenna (and/or a signal booster) -- you'll need to affix the antenna in place somehow to know its true performance. It may work OK with you holding it in place, but not OK when you're replaced by a coupla thumbtacks, or pieces of painter's tape, or Blu-tak.

I suppose it's good that we're not always 100% replaceable, eh?

msg

This is pretty good, guys, thanks. I'm up and running

Currently a hybrid of suggestions. I'm using the 'vertical' orientation I think. Sideways T? This particular setup has the tuner at about eye level for me, so the antenna goes out the back, across the wall to the right, through a corner, then over to a window. Here, I've got the legs stretching up and down about 8" back from the opening. I noticed some interference with it running across the very edge of the window opening, and realized that this is where the metal drywall corner edging runs.

The Bluetack is a great idea. I bought a bunch of that stuff a while ago thinking I'd use it for bookshelf speaker feet and whatnot. Right now I've got it secured with 'decorative' blue painters tape, but Bluetack would be better for playing around with the positioning. I might switch to that and then see just what exactly it does for signal with it positioned right at the window edge without me touching it. You're right Doc - signal reception varies greatly with orientation and even just my proximity to it, not even having to touch it.

Okay, so this particular dipole has the spades at the end. The tuner uses coax. So I've got one of those cheap slip-on spade to coax converters. It's cheezy. I have another dipole antenna that terminates in a coax connector. I was thinking of using this one with a length of coax as an extension over to terminate at the tuner. I would make a better connection at the tuner than the spades one. Does this run of extra coax then become part of the antenna? I wonder whether it will be too 'heavy' and affect the signal.

Last question - perhaps better for a new thread - FM Stereo is still a little noisy
Mono is very nice and clean. This is mostly for classical music, and probably some old jazz and stuff. I imagine I'll have to give this a listen for myself, but wondering whether I'd be missing much if I just listen in mono. Does seem to lose some 'body' in mono, but it's very clean.

These are the programs I like to use the real radio for. I can stream all of these as well, and while cleaner, there's a definite loss of body in the broadcast vs that of FM.

Local Classical Music Station
Prairie Home Companion
Saturday Night Fish Fry
Juke In The Back
Mountain Stage

mhardy6647

Only one short answer for the moment (I am actually busy with something, if you can imagine such a thing!) -- personally, I'd (much) rather listen to excellent mono than so-so stereo FM. YMMV, though, of course.



I'll get back to you anon about the other questions/comments!

FestYboy

It would be easy to add a line amp to your co-ax lead... That may help your stereo reception. In that same vein, you also have the option of running the antenna to a more appropriate position then use the line amp to keep the signal strength up through the shielded co-ax.