MaxiProx optimum read range Continued
AN010f.doc
PAGE
Date: 1-28-
99
by Eric Sprik
Updated 5/21/01
4
Metal Gooseneck
The metal gooseneck plate should be less than 3 inches in diameter if round,
and 4 inches if square. The non-metal spacer should be about an inch thick.
With this arrangement, the metal has minimal affect on read range, and once
tuned, read range will be optimal.
You may have noticed that whenever read range is described,
indefinite words like “approximately”, “about”, and “nominal” are
often used. That is because RF proximity reader performance is
not perfectly predictable. Each mounting location is unique with regard to
metal and ambient RFI. But the less metal there is, and the farther away from
the reader it is, the better.
In reality, avoiding all metal in the mounting area would be impossible. The
mounting screws are metal, the wall studs may be steel, or there may be a
section of existing conduit in the wall. This is why the MaxiProx was made
“tunable”. Once the reader is mounted it can be tuned for best performance.
There are two antennas in the MaxiProx: one generates the excite field, the
other receives the card data transmission. To keep these antennas from
electrically interfering with each other, they need to be “nulled”. Please refer to
the installation manual tuning instructions.
The receive antenna is a three inch circular coil in the upper left corner of the
reader. It is obscured by the antenna frame, and held in place by two Phillips
head screws. Loosen the screws, and put the unit in “coarse mode” by
turning off DIP Switch SW1-9. Power does not have to be cycled after
changing the course/fine setting. Turn the white knob (in the middle of the
antenna) until the null LED is steady green. Set the unit back to “fine” by
turning on SW1-9, and turn the white knob again slightly to make the Null LED
steady green again.
If there is a lot of metal in the field, slide the antenna toward the center of the
reader. Sometimes there is too much metal to allow the fine tune. In this
case tune it until the Null LED is blinking as slowly as possible. Be sure to
tighten the screws just enough that the antenna doesn’t slip. Avoid over
tightening these screws.
TUNING
