In an embodiment, an apparatus (e.g., a gas detection device) includes a housing, a printed circuit board (PCB), one or more radio modems with a switching network. The housing includes a conductive cover and the cover plays as an antenna. The PCB may be fixed in the housing and includes a ground plane and a plurality of conductive feeds. Each feed are vertically mounted directly or indirectly on the PCB. When the cover is attached to the housing, each of the feeds electrically contact a respective connection point on the antenna. The switching network is to configure which feed should be connected to the radio modem. A extra grounding resistor is mounted or not to change antenna type to enhance the performance of antenna.