Wireless security alarm systems are ideal for installation in a home that wasn't wired for an alarm system when it was built. Motion sensors, door contacts and window contacts can all be wireless, and not need to be hardwired back to the main control panel. Even the control keypad can be wireless.

The various wireless components use RF (radio waves) to transmit their signals back to the main control panel. The only real disadvantage compared to wired systems is that the wireless components run on batteries, which will need to be replaced once in a while.

These batteries generally last for years, however, and many alarm companies offer service and maintenance plans that will cover the replacement batteries and the installation of them.

The most common wireless alarm components are the following:

Control Panel

This is essentially the "brains" of the alarm system. It's usually mounted somewhere out of the way, like a closet or the basement. It monitors the signals from all the wireless components, and triggers the alarm (and a call to the monitoring station if the system is monitored) if any of the sensors detect an intrusion.

Keypad

The keypad is used to arm and disarm the system, as well as change various settings. It's usually located somewhere near the entrance door for easy access.

Magnetic Switches

These contacts are used to monitor windows and doors. They're made up of a switch that attaches to the window or door and a magnet that is mounted on the frame. If the switch and magnet are separated (the window or door is opened or broken) it will trigger the alarm.

Motion Sensors

Motion sensors can be mounted in large rooms or areas like hallways. They will detect motion - and in some cases body heat - and trigger the alarm if it is out of the acceptable range.

Video Cameras

Wireless security cameras can send a video feed back to a monitor and/or a VCR in the house. They can be used to monitor outside areas that are not very visible from the street, as well as a way of seeing who is at the door before opening it.

Remote Keys

Remote keys are much like the remotes you get with car alarms. They can be used from a distance to arm or disarm the alarm, as well as things like turning lights on or off or unlocking doors.