A Polar Reference Map of Hawaii Polar Projection Map Centered on Hawaii

Which Direction to Point That Beam?

One of the surprises of Hawaii, or any location, is just which compass direction distant places are from here. A custom polar projection is a very valuable tool to figure such things out.

Even dipoles have radiation patterns that are directional, but the direction the wire runs is often dictated by what will fit in the limited space available.

The first problem is to get from the traditional local "relative directions" such as Mauka, to actual compass references, the concepts seldom used in Hawaii such as "north" and "east".

Streets are usually not much help at all, since they seem to delight in going on all sorts of wierd angles. Besides, when North and South King Street run mostly east and west and North King is south of South King Street, it is not surprising that few in Hawaii can actually point north from any given location. In fact, finding any map of Hawaii that contains latitude and longitude lines is a struggle, and many maps of Hawaii seem to have even given up on the tradition of printing maps with north at the top!

Surprisingly, McCarthy Mall in the center of the UHM campus is rather "normal". Its main block-long center sidewalk runs very close to East and West. The mainland is at about 60 degrees, from the center of McCarthy Mall, that is just up over St. Louis Heights. The sidewalk points about at the northern edge of South America. Just when you assume everything in Hawaii is built cockeyed, they throw you a curve.

Even determining directions with a magnetic compass of good design can be tricky. Condos and other buildings, power lines, etc. have tremendous effects on magnetic compasses. Often condo dwellers have to go out into the parking lot and sight along building edges with a good compass to get reasonable readings on which way lanais or possible antenna paths actually run.

Compasses point towards the Magnetic North Pole even in the best of locations, and that is not at the north pole. It is in North Central Canada. That means that the magnetic deviation in Hawaii is about 11 degrees. So when your compass needle points "north" it is actually pointing at North Central Canada, or about 11 degrees East of the geographic north pole. Keep that in mind when you convert your magnetic compass readings to true readings. You need to subtract 11 degrees from your readings. If you compass says something is 39 degrees, it is actually closer to 28 degrees true.

A final resort is to wait for a clear night and find Polaris, the North Star. From a specific place on your lanai or other antenna site, make a note of what is directly below that star, such as a telephone pole. The Little Dipper is often difficult to find in city light areas, but usually you can make out the Big Dipper and its two "pointer stars" that will enable you to track down Polaris. The next day you will have a true north/south directional reference.

The UH Manoa Bookstore sells a terrific map for one of the Anthropology courses that is a detailed map of the Pacific about the size of a sheet of legal paper, but containing all the political boundaries of the various South Pacific Island groups and most of the important islands. They also have individual Hawaiian island maps with latitude and longitude lines on them.

The also have a map of "Oceania" that is worth getting to help figure out just where Truk, Chuuk and other interesting places you talk to really are. Hams there are often surprised to talk to someone who actually knows where they are located. Quick! where is an A35 and Haapai and which way is it from here!

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08/99