Ramsey Electronics URC1 Instruction Manual download pdf (Page 26)

WSR-1A• 26

ANTENNAS

There are several considerations when deciding what antenna to use with your

WSR-1. As with almost everything there are some sacrifices to be made with

each gain. Here are a few ideas, pros and cons that you can go by when

choosing a suitable antenna.

The crossed Yagi antenna is a popular form of antenna for polar orbiting

satellite reception. This antenna is about the size of a TV antenna, has greater

gain, yields stronger signals, and must be aimed towards the satellite as it

passes. This requires two rotators, such as TV antenna rotators, to move the

antenna in both elevation (altitude) and azimuth (bearing).

The satellite tracking software used for timing the rise and set of the satellites

will also give you the information you need to track the satellite in azimuth (from

0 to 360 degrees) and elevation (0 to 90 degrees). The antenna is often

"pointed" manually using the rotator controls located near the receiver. This

means that automatic, unattended recording cannot be done without additional

equipment. More sophisticated systems use a computer to track the satellite

with software and a controller interface to the antenna rotators. The advantage

of this type of antenna setup is that low satellite passes of high image quality

can be easily recorded. Satellites only a few degrees above the horizon can

often be recorded with very little noise. This allows a full, high quality pass,

nearly horizon-to-horizon to be recorded with the NOAA satellites, a picture

2940 miles long by about 1875 miles wide, it comes to over 5.5 million square

miles with a resolution of 2 to 3 miles (in the center of the pass). For a receiver

in Florida that means a picture from the northern part of South America to

Hudson Bay! In addition, because of the narrow beam width, extraneous noise

sources often do not interfere with the satellite signal.

The disadvantages of a controllable Yagi are complexity, higher maintenance,

and cost. Many users find that the stationary turnstile antenna is very adequate

for their needs.

Turnstile antenna: Just a simple pair of dipoles, the turnstile antenna has good

characteristics for non-manual tracking. You can leave this type of antenna

sitting on your roof, and never have to worry again. The problem lies in the gain

of the antenna. These have lower gain than the multiple beam antennas, and

result in pictures that are not as clear, especially on weaker signals. Also

antennas are never mathematically perfect, they have areas with nulls where

the image and signal will fade out entirely, and other areas where the signal

comes in very strongly. The advantage is that they are easy to make, and

inexpensive. This is the type of antenna we recommend and give directions on

how to make.

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Ramsey Electronics URC1 Instruction Manual Page 26