SimpliSafe Door/window-open sensors have notoriously short ranges. This makes it difficult to use sensors more than 20 or 30 feet away from your base station, if there are any walls in between.
Many SimpliSafe customers have asked the company to provide some signal boosting capability, but to no avail. Many a garage, guest house, pool house, and shed is unprotected by SimpliSafe because of this simple design flaw.
If you get frequent “door or window is open” warnings, or “sensor XXXXXX is out of range errors,” you may be able to fix your problem by boosting the signal of the sensor in question. You can boost signal by extending its antenna, which is very inexpensive and relatively easy to do. This MAY be enough to get your base station and sensor talking too each other again.
Happily, it is straightforward to boost sensor signal output significantly by extending its antenna. This Instructable shows you how.
NOTE: THIS VOIDS THE WARRANTY OF THE SENSOR. It should not, however, void your SimpliSafe warranty. The alarm system will still work fine.
Step 1: Open Up the Sensor Case
Carefully pry the back off the sensor, then carefully pry the circuit board loose, without breaking or cutting any of the wires.
Step 2: Drill Wire Hole in the Top of the Case
You will need at least a meter of thin coated electrical wire, as pictured.
On the bottom of the circuit board you will see a stiff wire protruding about 1/4 inch from the circuit board. That’s the built-in antenna. We will solder our wire to the TOP of that antena, thereby extending its radio range.
Find the spot on THE TOP of the case, indicated in the picture, where the wire should protrude, and mark it with a thin sharpie.
Choose a drill bit slightly wider than your electrical wire, and carefully drill a hole at that spot.
Step 3: Solder the Electrical Wire to the Internal Antenna
Strip a half inch or so of your electrical wire, feed it through the hole you drilled in the case, and carefully solder it to a corner of the built-in antenna, as shown.
Then carefully reassemble the sensor.
Step 4: Trim the Antenna to One Meter
The SimpliSafe sensors communicate with the base station at frequencies between 300 and 400 MHz. The wavelength of a 300 MHz Signal is 1 meter. Antenna design is complicated, but in this case, a 1-wavelength antenna length ought to work better than a 2-inch antenna, which is a small fraction of a 1-meter wavelength.
Long story short: trim the wire to 1 meter.
Step 5: Reattach the Sensor to the Door/Window
Pick a low enough spot for the sensor on the door or window, because you’re going to tape the full meter of antenna up from the sensor.
Using strong Double-sided tape, reattach the sensor and its magnet close to each other across the gap, as usual. And tape the antenna above it, as pictured.
Step 6: Check Your Keypad!
With any luck, your base station can now easily tranceive signals with your “hotter” hacked sensor.
This means you should no longer get “Sensor is open” or “sensor out of range” errors. In any case, that’s what happened for me.