I agree; mileage figures are only useful to compare different models of the same brand. What counts is how strong the signals are at your location, and putting it in the attic makes them even weaker. What good is a 55 mile antenna if you happen to have a hill five miles away that blocks the signals?
Has anyone made a 300 ohm twin lead antenna?
Yes, the twin lead folded dipole is one of my favorite antennas.
Many years ago I was located between Richmond and Norfolk. In my attic I had a folded dipole or a 5 element single channel yagi cut for each channel. I had a 2-pole, 12 position ceramic switch with its shaft extended below so that I could select which antenna I needed. It worked very well. All the feed lines were 300 ohm twin lead, which is why I used a 2-pole rotary switch.
At my next location, I only used the Norfolk channels. I had a 4-bay UHF antenna and a folded dipole for 13 connected to the original 7777 preamp that had separate inputs for UHF and VHF. The antennas were only 5 feet AGL, but reception was satisfactory. The UHF and VHF channels were about the same strength on my report, but 13 was weaker for me because of the lower gain of the folded dipole.
At my present location I am closer to Norfolk and am able to use a GE 34792 Attic Antenna indoors at ground level. Channel 13 is again weaker because the GE antenna only has a single element folded dipole for VHF-High. The UHF section has more gain, so I can get PBS on 16 which has Create, one of my favorites.
You can suspend a twin lead folded dipole for channel 3 in your attic to see how it works.
Channel 3, 60 to 66 MHZ, center frequency 63 MHz
5540/63 = 87.9 inches length for a folded dipole antenna