Cellphone-Mate CM222 3dB Indoor Dome Antenna Brand New Cellphone-Mate CM222 3dB Indoor Dome Antenna for Inbuilding Amplifier System. The Cellphone-Mate CM222 3dB gain dual-band dome antenna improves signal on cellular, iDEN, and PCS networks. This ceiling mount dual-band antenna transmits and receives to cell phones with a 360 degree beamwidth. Includes mounting equipment to allow antenna to mount through the ceiling. Requires a 50 ohms cable (sold separately).