Building your own tuned-loop AM antennas

[exray]

Texasrocker Wrote:You will never find a better-performing antenna! These loops beat out any & all outdoor-strung longwires antennas, period!

Hi Randal, I think you're over-reaching there I do loops and I think they are great but rarely are they are match to a good outdoor antenna unless there's some fluke about the outdoor wire's placement. Mr. Loop's biggest advantage is the ability to null out things which you cannot do with a hundred feet of wire in the trees. Rule of thumb is that a loop is lower by 20-30db than a random wire so it depends a lot on what you're trying to listen to.

Each has its place. A good radioman will have both at his disposal to see which works best. For me its an outdoor wire hands down. I " heart" loops for some purposes but you put a loop on a crystal set and you'll see the impact of that 20-30db down stuff.

-ex

[Texasrocker]

Hello Exray. In my location, my loop-antenna way out-performs all my outdoor longwires on all my vintage radios from trf designs to superhets ( that never had a factory antenna) for long distant reception.I plan on building somemore crystal sets soon as I ran across a vast supply of rare vintage ITT FO-215 detector diodes recently.I dont have anymore Crystal sets around to try as of now. I have 3-longwires, a 35' , 50', & 75' properly-strung on ceramic-insulators horizontal outdoor longwire selection (switchable) into my workbench inside my metal building where I service radios.I keep my horizontal strung longwire(s) serviced and checked. All strung on towers approx 14' above ground level. None of my outdoor LW antennas will receive WLW 50KW ( 700 kc) clear-channel from Cincinnatti ( well over 1200 mi away to my qsl), and I can receive WLW on my 1927 Radiola 18 with the loop, while nulling out several Mex stations & one in the rio grande valley all on 700 kc. Next time your in San Angelo, Tx, ( actually im outside the city about 12 miles in the country) drop by my shop and listen. Im not braggin on this antenna at all, Im sure reception varies all across the US, but for my location, the loop adds more db gain into all my radios especially the distant stations after dark. Im not sure about the Crystal sets tho. Never tried that combination setup. My qsl location is approx 110 miles north of Del Rio, Tx. To say the least, WLW Cincinnati is a far-stretch for reception here, but since my wife is from that area, she enjoys listening to her hometown station here in W Tx!! The loop-antenna pulls in WLW, & KOA 50kw in Denver sounds like the transmitter is just across the street from us, with absolutely "no fade in-out" on KOA 850 khz. WLW does fade in-out abit here on the loop, but at least we can hear the Station after dark. Everyone else ( on this forum & others) that has built one of these designs loop antennas has reported same results as mine from various locations across the US. Works for me anyways!

[Ron Ramirez]

More photos of Randal's loop antenna...

Showing some of the parts necessary to add a swivel base to Randal's loop.



The next two photos show the assembly of the swivel base.





Finishing up the swivel base:



Preparing to add the loop holder to the swivel base:



The loop holder and swivel base, assembled:



More views of the loop holder, swivel base and the loop itself:

[radiorich]

Well guys,
I was wondering far as thast copper loop goes why couldn't a guy use one of those old loop UHF antenna's that they used to give with our tvs.
Sincerely Rich
Hello Ron far as the wooden structure for the antenna you you have the dimensions of it also Ron that swivel looks to be a mini size one right not the ones you see on your rocker.
Ron nice shop there in the back ground also that antenna turned out nice I have huge stock pile of old reclaimed fur from the late 1800s from olf house though that would be nice to make the stand from also far as the wire is that 20 ga. standed right. also is that just good old Rg59 coax right

[exray]

Rich, even poor wire will make a good loop antenna. Don't be skeered off with 20ga stranded. Use good litz and you can shave off the s's on the low end of the band because of the selectivity and you'll see improved notching abilities. That can be TOO sharp for comfort on a 'consumer' radio.

The 'pickup' loop isn't all that critical. There's some advantage to minimizing the coupling for hard-core DXing but the general references to the pick up loop like a turn wound on the frame or a 12" dia loop in the center, or even placing the loop close to a radio that has its own internal loop with no connection, all work great.

Wind one of these puppies with good litz wire and you'll want a vernier drive on its tuning cap!

[Ron Ramirez]

Rich

Sorry, that isn't my shop...that is Randal's (Texasrocker's) shop. I merely posted the photos he provided me.

Regarding the dimensions and other details, Randal will have to fill you in...what say you, Tex?

[codefox1]

I hve a loop and it works really great. I'd really like to see a design that could null out signals that are in a plane. IE if I am in a North-South plane, and am getting competing signals from East and West, and I would like to null out the West and only pick up the East, what do I do? I was considering building two loops and somehow phase them, and a long time ago I saw something about adding a whip antenna to do what I am trying to do, but I lost the link. Any ideas?

[radiorich]

Hello Exray
Speaking of litz wire I'll post some photos shortly of the rolls of that litz wire that was dropped off at the recycling business
were I worked for a while your jaw will drop there is like 3 rolls of it but can you buy that stuff new because I was going to save it to use in restoration of my old radios that need say a replacement antenna or a if coil rewound.
Sincerely Rich
P.S. Ron Well I guess Texasrocker has a nice shop then

[Texasrocker]

Hello Guys. Ron, Thanks for adding the photos here!! The "most important" part of this loop-antennas design is the center approx 6" diameter secondary loop, and how it is connected to the main antennas tuning-condenser (metal mounting frame) that feeds coax to your radios. In most previous loop-ant. designs, the center loop is not connected at all to the tuning condenser! Those designs ( air inductance design only between the 2 loops) dont allow for good reception on all sets. This design works!
If you go back thru these threads, & photos, you will see the center secondary loop ( approx 6" in dia) is bent in a approx 6" circle & then ( terminated)soldered mounted to a regular 2 point phenolic terminal strip. The guage of the wire is not critical, just needs to be "stiff wire". A leftover pc of 12 or 14 ga romex copper works well, as you can solder coax to it with hot solder iron.
To make this antenna design work with ALL vintage radios, ( pay attention here!!!!) "a short "jumper wire" must be added back to the antennas tuning-condenser metal outer-frame from either side of the center-loops terminal-strip"!!!!.
From either side of the 6" loop, add a flexible-type 50 ohm ( RG-259 or similar) 4' or 5' pc of coax out to feed your vintage radios antenna screw terminal via coax center-lead. The coax braid is not used at your receivers-end ant connect, but solder it to the unused side opposide coax lead on the terminal-strip opposite of coax center leadwire. The braid keeps out stray RF along the coax to your vintage radio receiver. Only the center-core of the coax hooks to your radio, so cut-off excess braid or tape it back out of the way when connecting your cntr-lead of the coax to your radios antenna screw.
The "jumper wire" is VERY- critical!!!.. from the center-loop back to primary loop tuning-condenser frame!! A "free floating" 6" inductance only design type 6"cntr loop does little,or, no good at all for connecting directly to vintage tube radios! Instructions for building the primary-frame with 18 turns of 18 ga wire ( or similar) and all exact measurements can be found in the first post on this thread. When winding the primary loop, it is also very important to rtn both wires ( going & returning 18 loops)..to the tuning condenser along the same wooden leg of your "X" frame. A staple gun comes in handy!
Build one, dont forget the "jumper"!!!, and your in max DX heaven indeed!

As for the rotating-base, as you see in the photos, allows for loop antenna to "sit" in the base or be removed. I used a 4" x 4" "lazy-susan" ball bearing castor I found for cheap on ebay. Most of the base is scrap 1" x 4" pine I had laying around the shop, and a couple pcs of scrap oak plywood stained with dark-walnut stain. The woodwork isnt great, but the antenna works extremely well!!... and rotating it easily is only a added feature for "aiming" the antenna without touching the loop and changing inductance while station-surfing. Works GREAT here!!

[radiorich]

Hello Texasrocker,
thanks for the info far as that antenna goes it looks like fun project to do.
Sincerely Rich