This website details the design and construction Wave Bubble: a self-tuning, wide-bandwidth portable RF jammer. The device is lightweight and small for easy camoflauging: it is the size of a pack of cigarettes.
An internal lithium-ion battery provides up to 2 hours of jamming (two bands, such as cell) or 4 hours (single band, such as cordless phone, GPS, WiFi, bluetooth, etc). The battery is rechargeable via a mini-USB connector or 4mm DC jack (a common size). Alternately, 3 AAA batteries may also be used.
Output power is .1W (high bands) and .3W (low bands). Effective range is approximately 20′ radius with well-tuned antennas. Less so with the internal antennas or poorly matched antennas. [via]
Wave Bubble: a self-tuning portable RF jammer – [Link]