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Big Loop Antenna

Posted: Fri Jul 17, 2020 4:27 pm
by P-40 Warhawk
Hi Every body .
Maybe someone might know . Here is what my problem is , I used the Aluminum Fascia on the eaves of my house for a horizontally oriented loop antenna . It came out to be about a full wave antenna at 80 meters and the DC resistance was about 4 ohms .
Now about six years later the DC resistance has gone up to 68 ohms and the performance of the antenna has fallen off .
What I am thinking of doing is running a 10 gauge wire along the Aluminum Fascia of the house . The question is am I going to have a problem with the electrical capacity from the Aluminum Fascia and the insulated 10 gauge wire ????? All so should I use strand wire or solid ???????

Re: Big Loop Antenna

Posted: Sat Jul 18, 2020 12:31 pm
by snn47
How were the Aluminum Fascia pieces connected to each other?
Unless the Aluminum Fascia is heavily corroded at the connections, maybe just redooing a limited numbers of connections might be a solution for you.

Running both in parallel should increase capacitance unless you connect the cooper and the Aluminum Fascia, but I can only theorize what this will do your reception.

If it is for receive only as I assume, then just stringing a thin cooper wire (e.g. a wire unwound from a discarded transformer) along the Aluminum Fascia and test how the wire works before you spent time and money on a 10 gauge wire.
About 0.4 mm diameter Copper wire would give you the 4 Ohm resistance.


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Re: Big Loop Antenna

Posted: Sat Jul 18, 2020 1:26 pm
by P-40 Warhawk
Hi Snn47 .
The aluminum fascia pieces are connected to each other with 4 stainless steel screws . You are right that this is for receive only The wire size is 10 gauge , is the size that is recommend for antennas because of the surface area . If I understand what what you are saying , Running both in parallel may be a good thing .
Thank You for getting back to me .

Re: Big Loop Antenna

Posted: Sun Jul 19, 2020 10:52 pm
by snn47
For Aluminum and Stainless Steel you can find an overview here. https://www.albanycountyfasteners.com/b ... -aluminum/ . There are different types of Stainless Steel and Aluminum, which have different percentage of other metals in it, which may influence corrosion too.

I cannot make up my mind which effects dominate if you run a cooper cable close to your aluminum fascia and how this will influence reception, which is why I suggested that you try it with a smaller diameter, in parallel and solo.
You are right that this is for receive only The wire size is 10 gauge , is the size that is recommend for antennas because of the surface area .
There are calculator for the resistance of cooper wires in the net, where you can see the decrease in resistance with increase in diameter. Larger diameter will increase capacitance, but this provide only some increase in bandwidth
Can you use a long wire in your yard? ANtenna are only resonant for the basic frequency and multiple of it, but the pattern will vary compared to the fundamental frequency.
For most of the frequencies antennas are not resonant, but still receive decently. Thats why using a long wire worked well for me. Try it, stick thin cooper wire in a potatoe and throw it into the next tree. I used thin cooper wires of varying diameter that I unwound from discarded transformers for many years sucessfully for transmisions on shortwave for temporary (years 😉 ) antennae.

Re: Big Loop Antenna

Posted: Mon Jul 20, 2020 4:58 pm
by P-40 Warhawk
Hi Snn47 and thank you for getting back to me .
The back of my yard borders a wetlands and that is were the trees are , Now that would eating a lot of coax cable getting to my house . So without trees in the back yard getting something up isn't workable . Unfortunately I don't have any junk transformers . The Stainless Steel screws came from the hardware store and their isn't anything on the box to tell you what the makeup is of the screws . If I understand you more capacity is better for a antenna . Using the Aluminum Fascia like a reflector , I hope would be a good thing or do no damage .