Test Report for NCE High Gain Antenna

by Don Fiehmann

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Layout operation is greatly enhanced with walk-around throttles and cabs. But being tethered to the layout is a pain when you are following a train. The NCE wireless cabs solved this problem. FCC rules restricted the transmission power allowed for this type of service to a very low level. This resulted in spotty operation on some layouts. One of the first suggestion for improving this was to add a ground plane to the base station. Adding a pie tin or pizza tin under the antenna helped with quicker response and better range. Placing the unit up at a higher location also helped. Many were mounted upside-down (antenna pointing down) near the ceiling.

The original antennas were short, stubby, 1/4 wave length, and somewhat ridged. With operation in the 900 MHz band the 1/4 wave antenna was just over 3 inches long. NCE has released a 1/2 wave replacement antenna that is thin, flexible, and just over 7 inches long. The new antennas are $16.95. To install just unscrew the old 1/4 wave and replace it with the new 1/2 wave antenna. The group I belong to bought some of the 1/2 wave antennas. Howard McKinney replaced both the base and cab antennas and said that the dead spots he had were gone and the faster response made it easier to work the whistle. Tom Towner had a dead area about 2 foot wide that reduced to less than 6 inches. I had similar results on my layout.

The new antennas are better, but how much better? My curiosity got the best of me so I decided to run some tests.

To start with, if you get too close to the base station the receivers will overload. With better antennas that produced more signal strength the overload should occur a little further from the base station.

My test was to push the direction button and watch for the display to change from FRW to REV. This way I know that the message got to the system and the return path was also working. I moved my base station to an open area and then checked the distance. With the old and a mix of the old and new antennas the overload distance varied between 2 and 3. feet. With new 1/2 wave antennas on both the overload distance was about 4.5 feet.

Testing indoors is a problem due obstruction and reflections caused at this high frequency. Even your body between the base and cab causes a reduction in signal strength. I moved the base outside on the sidewalk setting it on a small wood TV tray. This way I could test the distance using line-of-sight. Two tests were done for each different antenna setup. Both used the direction button response as the test. First I walked from the base to a point where the response failed. This put my body between the base and the cab. The next test was to see the distance where the signal was lost without my body in the way. This was done by walking beyond the systems range and then walking back until I could reliably communicate. I found that it was hard to determine the point at which the signal failed and response just got very slow. So the measurements are approximate. The pattern from this type antenna is donut shaped so best transmission happens when the antennas are parallel to each other. For each test the sidewalk was marked with a different colored chalk. Tests were done on a sunny California day. The red LED on the Pro Cab used to show activity was barely visible in strong sunlight.

Test Results Comparing Antennas

*with Ground Plane (Pie Tin)

Conclusion

Even though this test was not done under laboratory conditions, it does show the differences between antennas. Adding a ground plane to the 1/4 antenna helps. The biggest improvement comes with the 1/2 wave antennas. With the base station in the center of an open area you would have a range of over 300 feet. Everyone that has tried the half wave antenna reports faster responses at all distance ranges.

Placing a body between the base station and cab has a significant effect on range. Things like water heaters, metal ducts and furnaces can have the same effect. Like they said in the gas mileage ads - your results may vary.

Tests run on 26 May 2003.
Document 28 May 2003.

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