After Chicago went digital, even though I have Comcast, I decided to see what was available off-air. I had a tabletop Philips UHF antenna from another project and I bought an Apex DT250 tuner. Everything from Chicago came in as it should have at about 70% signal strength, as measured by the gauge in the Apex box. Yes, Lord knows what it's measuring, but I don't have any other signal strength meter. The big exception was WBBM Ch2 and WLS Ch7. For whatever reason, those broadcasters decided not to go UHF at the transition and, instead, went HiVHF. WBBM is at RF Ch12 and, after some fooling around, WLS is back at RF Ch7 where they were in the analog days. I've been in a lot of discussions about the wisdom of this HiVHF business, my opinion being that there was no wisdom in this HiVHF business, but now, several years into the Great Digital Experiment, WLS has set up a "fill-in" transmitter on RF Ch44 and WBBM is in the process of doing the same on RF Ch26. WLS now appears on the Apex at RF Ch 44 just fine. I'm hoping for WBBM to do the same, but, well, knowing their puzzling past, we'll see what happens.
OK, so no WBBM and no WLS. I started studying antenna designs and prices. I'd pretty much decided to build my own and I am forced to do an attic mount. I came across the Gray-Hoverman design and thought that looked promising, but I was sold when I read in some on-line forum that it did a reasonable job with HiVHF. Frankly, I didn't want to mess with wood and screws just for an experiment and I had some 2'x4' foamcore panels, styrofoam blocks and blue painter's tape around from yet another project. I went to Menard's and bought 50' of insulated solid 14 gauge wire and got to work.
The design I chose was the one at http://www.digitalhome.ca/ota/superantenna/design.htm
. I just drew out everything on the foamcore board, bent the zigzags, taped the wire down with the painter's tape, soldered on a balun, used a broomstick for a mast and an old brake disc for a base. Took about an hour and a half. Later I added another foamcore panel with the reflectors/narods, whichever they are, held in position with styrofoam blocks and some Elmer's Glue. It isn't pretty and it PO'd my wife. Success! It works great on UHF as one might expect, everything's at 97% and reception of WBBM and WLS are fine as long as it isn't raining. WBBM is at 25% and WLS is at 52%. WBBM is the flakier of the two, overall. Now that WLS is at fill-in RF Ch44 using the G-H really doesn't make a difference and I'm hoping WBBM's fill-in does the same. Occasionally, I can get the PBS station from Gary, as well. And, that's my indoor Gray-Hoverman. I've since ditched the brake disc and screwed the mast to a rafter.
Some things to know about my setup...
I live in Prairie View, IL which is 27 miles as the crow flies from Willis (nee Sears) Tower where all the Chicago transmitting antennas are. If I stand on my roof, I can see the top of Willis Tower just above the ground clutter, so line-of-sight is literal. My antenna is about 12 feet off the ground in my attic. It is 25 feet between my Apex receiver and the antenna. I'm using RG59 cable because I had a lot of it laying around and I know I'd get a better signal if I used RG6, but this was done on the cheap, you know. I also have a Radio Shack amp in the line. Pipe down...it was cheap and it works just fine. I don't necessarily recommend it, but I've got a good one. There are other brands with way better hardware and reputations. The UHF, btw, is OK without the amp, about 78%, but WBBM won't come in without it and WLS RF Ch7 is iffy.
I was prompted to write this because of 2edge from Woodstock who has to use an attic mount. You're about twice as far away from the Tower as I am, but you're also about 300' higher in elevation. I think the success of this depends on what your roof is made of and what ground clutter (trees and other houses, water towers and suburban sprawl) is between you and Willis Tower. And, aim carefully. Before I realized I could actually see Willis Tower from my roof, I did some aiming with a Trib map and a Silva compass. I liked that. It was fun and scientific.
Truly, I recommend doing this with tape and styrofoam to see what kind of reception you could get, even if you have to go to Hobby Lobby and Menard's for materials. And, think seriously about an amp to beef things up if you get acceptable results. And, in any case, you're probably not going to get Ch2. Even in the analog days, there was just something about the Columbia Broadcasting System that didn't want people to actually watch their Chicago O & O. Puzzling. Maybe with the fill-in... Well, if you're satisfied with the results, you could go permanent with the "prototype" as I did, or use screws and wood or ABS pipe and chicken wire to make something sturdier.
Hope this idea works for you.