Outdoor FM receiver antenna testing

[@UQRXD]

I had one years ago and they work well. I also glue that plastic piece.

[@LarryKapp1]

glad you were able to fix it !

[@enriquediaz7547]

I got one of those to bring reception into my garage! It works! Very happy with it.

[@LarryKapp1]

Thanks for the report. It worked well here in my valley .

[@enriquediaz7547]

@@LarryKapp1 I live in an hoa-valley :) so it is really discreet too

[@beechpilot57]

Never saw a circular folded dipole but makes sense it should work good. To bad about the cheap plastic.

[@LarryKapp1]

I couldn't buy the materials to make this antenna for the price they sell them for. If the plastic ever cracked up at the antenna connection , I could probably rig up something better - but not sure the average antenna user would . Hopefully it lasts for at least 10 years. Now that I think about it - maybe it wouldn't be a bad idea to spray paint that plastic to protect it from the UV .

[@mediocreman2]

Good job keeping that old radio going. That's got to be at least 30 years old, right?

[@LarryKapp1]

You mean the GE Super Radio ? I picked it up from curbside years ago. I should clean it up , the pots in it need tuner cleaner spray job. And outside is so dirty from sitting in the shed. Those used to be a sought after radio for AM Dxers I believe. I think the rod antenna must have a bad connection since it didn't work at all with it - and works fine with the external connections. Maybe that is why someone tossed it ! Maybe I can work on it this winter when I have time.

[@joostderidder]

(first radio) Very strange that you get totally no reception with the built-in antenna. Probably a lose antenna-connection inside. Another thing that's bothering me a bit is the "grounded" 300ohm input. Normally a 300ohm input is not grounded. Do not buy those cheapo "twin"lines with a coax-connector already on, as you'll have a mismatch. Those lines are made using 300ohm "twinlead" so the one you have in use will perfectly match the 300ohm input of that first radio. Coax-inputs are 75 or 52ohms standard. Just "turn around" your impedance-transformer, connecting the 300ohm side to the twin-lead after cutting-off the coax-plug and plugging-in the 75 ohm into a receiver / tuner using a coax-input. Something you could experiment with is a self-made dipole-antenna. The formula is very simple: 14100 / frequency in Mhz For FM: 14100 / 100 = 141 ... that's the length in cm for a 52/75ohm dipole. Use 2 wires of (approximatively) 71 cm (2 x half the result of this division) connected to a coax-cable in the center. 100 is more or less the "center-frequency" of the FM-band. (100MHz) So if you'd like to make a dipole for 27Mhz ... use the formula 14100 / 27 = 522cm ... In this case you'll need 2 wires of about 261cm.... 2.61m connected in the center to a coax. A dipole for the MW will be very long ... lol .... "center-frequency" there is about 1Mhz ... so you'd have to make a dipole of 14100cm ... ->141m ... so two "leads" of about 70m !!! I hope your garden is big enough!!! lol lol Another thing that you should check is the polarization of the transmitted FM-signal. In Europe most FM-transmitters are using vertical polarisation. This is intended to make car-reception better. I don' know how the FM-polarization is in your country. (USA ???)

[@LarryKapp1]

Yes , I just responded to medio.. that I think that the rod antenna connection must be bad since it worked okay on the external connectors. I picked that GE Super Radio up on curb that someone put out for trash. Maybe that is why they ditched it. You are probably correct about the polarization of radio stations wanted to to be vertically polarized for car antennas - though now that I think about it the in glass antenna in my VW seems horizontal . And it doesn't work the best . I wish my car had just a rod antenna and I have thought about installing one but VW has some weird connectors on the existing glass antenna and an amplifier back there. So I would need to eliminate the 12v it sends back there but that is doable. But since I don't drive around too much it hasn't been a big priority. My Viofo dash cam makes some terrible RF interference to radio on weaker signals and that is why I looked into moving the antenna farther away from back camera. You know for the price of this FM antenna you can't even buy the materials let alone the time to make it . I have a very long FM radio log periodic beam antenna that I have never tried out - got it at a garage sale and haven't put it up yet. Lots of fun things to experiment with antennas !

[@dktr2]

These bent dipoles are bad; they have negative gain. Straighten it, and in horizontal polarization, it will become directional, while in vertical polarization, it will be omnidirectional.

[@LarryKapp1]

. The idea of these of course is to pick up stations from a wide area around it . But yeah in a weak station area that might help but might as well use a yagi if you just want a lot of gain in one direction. Probably for most people just getting anything outside their building is going to really help.

[@dktr2]

@@LarryKapp1 It depends on what you want to receive. If you’re looking for stations that broadcast in vertical polarization, you'll get better results by straightening it and hanging it vertically. If you want to receive everything around (H+V), then it’s better to leave it as it is. If you're interested in radio, check out my publicly accessible receiver with dipole antennas (H and V) mounted on a four-story building. To access it, just go to the website whose address is my username without the number 2, followed by dot 'pl' and then a slash 'XDR'. Cheers!

[@LarryKapp1]

I need to get my SDR hooked up to that antenna so I have a signal stength meter . Then I can see if straightening it helps . Not sure when I can get to that but sounds like a good experiment.