But as for specifications to make something inspired by those old antennas, there have been few plans. I have tried making a few different designs, and one works pretty good for shortwave and MW, but still it is not as good as a longwire out doors.
I took 2 strips of wood (mine was walnut) about 3/8 inch wide, about 3/4 inch thick. One was about 20 inches, the other about 24. I dadoed the two so that the longer piece had 4 inches extra length which attached later to a base. I set the blade of the table saw to cut a kerf 1/4 inch deep, and then while clamping the two strips together, started cutting kerfs about 3/8 inch apart. Until I reached a spot close to the dado, and then proceeded as before for the other side of the dado- using the same number of kerfs. I then took the longer strip and ran the blade lengthwise up the back of the longest "leg" to run the wire up in concealment. I wound about 100 feet of 26 guage enamel wire starting from the inside (with about 2 feet hanging off of the long end, and when winding-making sure that the wire pigtail was kept under the wire being wrapped. The other end of this long spiral, ends at the longest leg, and that wire gets routed down the groove cut in the back. These two wires get held in place with short bits of electric cord insulation pushed into the groove.
There are a lot of criticism to be made about it if you are looking at "optimal" antenna design, but this one works well enough for the application I intended it, and the cosmetics were more important for where it was going to be. I have also wrapped 75 feet of wire onto a styrene form, and hung that inside of the radio cabinet with good results too.
:I'd like to build an aerial for those old radios that required a long wire for reception.
:Are there specifications or plans to build such an aerial? I've noticed some pictures of these aerials sitting next to or on top of radios