When I was growing up, I used to watch my mother make dresses from patterns. I remember those thin sheets of brown paper with all those arcane lines and symbols that somehow came together to make a blouse, skirt or dress. Although she was pretty good at it, occasionally she would have to take apart what she had sewn together and make adjustments. But she always made it all work in the end. Many of her clothes and those of my sister were handmade back in the day. Occasionally she would tackle a shirt for my brothers, father and me but mostly she sewed for the women of the family.
My own interest in patterns would be in patterns of an entirely different kind; antenna patterns! AM radio stations come in two basic types, non directional and directional. Non directional stations broadcast in all directions with the same signal strength. But this sometimes creates interference with other stations operating on the same frequency. The station that was first to be licensed for that frequency must be protected from interference from the new station that is seeking a license to operate on that same frequency. Because radio signals travel farther at night, those stations can be quite some distance away. The radio signal is shaped into patterns by broadcasting from more than one tower. Generally speaking, the more the towers the more directional the station is.
I had the opportunity to work at two radio stations that sported directional antennas during my career. One of these stations had three towers and the other had six. Both of these stations operated non-directionally during the daylight hours and directionally at night. The station that had the six tower array actually had two different transmitter sites; the nighttime site was 30 miles northwest of the daytime site, which was located at the studio location. This station, which transmitted at 50,000 watts was located in Jacksonville, FL was required to protect a station located in Canada. The antenna pattern was so tight that the 10,000 watt nighttime transmitter could not be heard from the studio. Because the FCC at that time required that the announcer could monitor the on air signal live, the station was required to “pipe” the audio signal back to the control room over telephone lines.
Back in 1976, I was promoted to the position of “Chief Engineer” of the other directional station in my career. WIS radio was a 5,000 watt AM station that had a three antenna directional broadcast pattern at night. In these days of high powered FM stations, these power levels might not seem to be much, but you must remember that AM signals can travel much farther than FM signals can, especially at night. The 5,000 watt AM station has a slightly larger coverage area than a 100,000 watt FM station. Back in the heyday of radio, there were hobbyists who would scan the radio dial for that faint, far away signal. When they could identify the station, they would often send a letter or a “QSL” card to the station noting the time, date and program material to which they listened and request confirmation from the station so they could add another push pin to their maps and another station to their collector’s logbook. That hobby has sadly fallen to the wayside with the changes that have come to radio over the years. When I received one of these letters or cards, I would verify the program content, confirm the contact with the listener and add a push pin to my own map and note the contact in my own log.
Operating a directional radio station required that I go out into the field every week to measure the field strength of the station at four monitoring points located in parts of the station’s pattern called “nulls”. So, usually on a Friday afternoon, I would switch the station into its nighttime pattern, grab my trusty field strength meter and spend a quiet hour driving from point to point and taking the measurements. This was a high-spot of the week for me. Three of the four points were in rural, wooded areas where I could spend a short while enjoying the sunlight through the trees or the little rabbit that would greet me to beg for a cracker or some other treat. The fourth monitoring point was in the front parking lot of a John Deere lawnmower/small tractor shop. The proprietor of the shop was a semi retired farmer who always had a Pepsi, a Moon Pie and some great conversation waiting for me. That was a great way to wind down a hectic work week.
Today, the three monitoring points that were in the woods are now in developed neighborhoods. The shop is still there but my friend is not. He suffered a stroke the last year that I worked at the station and had to sell the shop to some corporation that runs these shops. Come to think of it, that is what has happened to radio too. Oh MY!