THE NRC AM ANTENNA PATTERN BOOK.
Each of the patterns contained in this edition are reproductions of pattern plots generated by a computer program written by NRC member Neil Adams. Although not perfect, each is a close reproduction of each pattern's shape and bearing. Sizes are proportional, but do not reflect the actual coverage areas due to the many factors which enter into the equation of where and how far an AM signal travels and can be heard. Some of these variables include frequency, a directional pattern (if used), the electrical height of the tower( s), ground conductivity, terrain, weather, atmospheric conditions, interference from other stations and of course, your receiving equipment. Sample Page
This edition of the Pattern Book is one of the most exhaustive undertaken to date, as we have included daytime patterns for the first time. Daytime patterns are depicted by a dashed line as opposed to the nighttime pattern which is defined by a solid line. Patterns are illustrated showing their intended shape and radiated power, but not necessarily their actual coverage area due to the variables listed above.
Every attempt has been made to place the number adjacent to, or least close to the city and in the appropriate state. In some of the crowded areas this was not possible. And in some cases, an arrow has been utilized to match the number with the location.
For those stations which operate with 50 kW (and higher in Mexico) non-directional (designated Ul in the AM Log), the day 'pattern' is shown to approximately the predicted 0.5 m V 1M coverage limits, while the night pattern is illustrated approximatelyI.5 times larger. For other stations which use the same power and pattern 24 hours, designated U3 in the AM Log, the night pattern is identical to the day pattern, but illustrated approximately 1.1 times larger. Keep in mind it's impossible to predict the actual coverage of any station.
Also added in this edition, by popular demand, are maps of the six "Graveyard" frequencies: 1230, 1240, 1340, 1400, 1450, and 1490 kHz. Generally, Graveyard stations all operate with a maximum of l kW, and their coverage is limited to 30-40 miles during the daytime, while nighttime coverage is limited 10-15 miles due to skywave propagation interference. Only a few operate with a directional antenna system, which are illustrated.
Stations in Alaska and Hawaii are listed on separate pages at the end of the book. All but three stations in these states are omni-directional. The three are on 580 in Petersburg, Alaska (same pattern all hours), 850 kHz in Nome, Alaska (directional during Critical Hours operation only), and 870 kHz in Honolulu, Hawaii (same pattern all hours). Those patterns are shown on a separate page.
The basic list of U.S. and Canadian stations comes from the 26th Edition of the National Radio Club's AM Radio Log. Only Mexican stations in the states bordering the United States, Baja California North (abbreviated BN), Chihuahua (CH), Coahuila (CI), Nuevo Leon (NL), Sonora (SO), and Tamaulipas (TA), plus those stations elsewhere which are easily heard in the U.S. and Canada are included. The source of the Mexican stations is a combination of data from the U.S. Federal Communications Commission and an up-to-date list of stations, as of press time, compiled by NRC member John Callarman. Please remember, information about Mexican stations is difficult to obtain and keep up-to-date.
Data contained herein is up-to-date as of November 1, 2005.
It is our hope that you find the data in this book a useful DXing aid.