See attached image for analysis details. Longer bars indicate stronger signals.My interpretation:
- The strongest signals (one with a green background) are probably good enough to be received using an indoor antenna like the Silver Sensor (known under many names like the Zenith ZHDTV1, Philips PM-HDTV1, or Terk HDTVi).
- The Philadelphia channels are pretty far away (58 miles) and they're very slightly blocked by some minor terrain blockage (1Edge under signal path column indicates single edge diffraction, as opposed to LOS, or line-of-sight). The signal strength from these channels is still very good, but you'll need a good roof-mounted antenna to get them. All the digital channels are currently in the UHF band, but I believe that WPVI will be moving to channel 6 (VHF-Lo) in February 2009. In the short term, you should get good results with a Channel Master 4228 or AntennasDirect XG91 pointed at Philadelphia. However, you may need to add a VHF antenna (like the Winegard HD4053P) in the future when WPVI changes to channel 6.
- WMGM, from Wildwood, should be coming in quite strong. The CM 4228 and AD XG91 are highly directional antennas, so you might not get WMGM while you have the antenna pointed at Philadelphia, but maybe you don't need to. You should be able to pick up WCAU to get NBC from Philadelphia instead of having to get WMGM. BTW, it looks like someone entered a typo into the FCC database creating an extra entry for WMGM-TD (instead of WMGM-DT).
- Other stations, like WWSI, W45CP, and WQAV are also nearby and strong. However, since they come from different directions, the directional antennas might not get them while being pointed at Philadelphia. You have the option of adding an antenna rotator to get these channels or alternatively combine multiple antennas to get the channels simultaneously. You'll have to decide if these additional channels are worth the added complexity of the antenna setup.
Trees can block some of the signal and cause multipath interference, at times. However, I believe the CM 4228 or AD XG91 have enough gain and directionality to give you a pretty good signal-to-noise margin to cope with those effects.
If you add a rotator, you should be able to get all the Philadelphia and local broadcasts pretty easily, but not all at the same time. This might pose a problem if you want to do unattended DVR/VCR/PC recordings.
If you install multiple antennas and combine their outputs, you'll be able to get all the channels simultaneously (good for recordings and general convenience), but these are usually more complicated to set up correctly and you'll be more vulnerable to interference sources (mostly multipath).
My suggestion is to start with the simplest/cheapest thing first and see if you like the results. Antenna reception takes quite a bit of trial-and-error, so be prepared to return products to the store if you don't like the results.
I hope this helps!