What you are looking at is a non-directional radio beacon (NDB) for the Bellingham Airport. The specific one you are looking at was called "BENZA", and operated at a frequency of 338 Khz. It sent out a constant Morse Code signal of "BL" and was used to help pilots locate the beginning of the instrument landing system approach path.
(see
http://en.wikipedia.org/wiki/Non-directional_beacon).
Many people used to monitor these NDBs as a hobby, and a few people, such as myself, used to track them down and photograph them. I have personally tracked most of the beacons in WA-OR-CA-ID over the last 20 years. Unfortunately, most NDBs in the United States have been decommissioned over the last several years because they have been rendered obsolete by newer navigation systems such as GPS.
I'm fairly sure that the BENZA NDB is no longer transmitting but you may be able to hear the outer marker signal on 75 Mhz AM if you get fairly close to the site. This will be just be a "beeping tone" and is transmitted by the inverted Yagi type antenna that you may have seen at the site.