You should know, frequency bands are main specification of cell phone jammers. Supported frequencies of jammer show whether jammer is compatiable with specific cell phone. It should be noted, network of cell phone uses radio signals that can be interrupted. Thus, digital cell phone & PCS-based systems use GSM & operate 900MHz & 1800MHz bands in Asia& Europe. In USA jammer opertes 1900MHz bands. Cell phone jammers affect frequencies of cell phone &disables signals of network. So, when you see that jammer has such frequency bands as 894MHz, GSM 925-960MHz, PCS 1920-1990 MHz, 3G 2110-2170 MHz, that means it can affet bands from 925 Mhz to 894 Mhz.
Effective radius range
The next step is to check effective radius range or blocking radius. Blocking radius is a distance within which it blocks bands. Jamming radius depends on signal strength and area. Each jammer has specific blocking radius, for istance, 20, 30, 50, 150 meters, etc.
Total output power
This is an actual power amount of radio frequency shown in Watts. In other words this is energy of transmitter, which it produces at its output. Each jammer has different output power, some models has 40W output power, 85W or 185W - which is high enough.
Antenna is a key part of every jammer as it sends signals. Remember, the more antennas have the jammer, then the stronger blocking signal will be. Some jammers are equipped with the external antennas to ensure longer working range. There are directional and omni - directional jammers. Jammers with omni-directional antennas send and receive signals in all directions equally. Antennas that work in specific directions at the expense of other directions are called directional antennas.
We hope thay this information will be useful for you and it will help you to choose the jammer that will answer your needs and wants.