Any knowledgeable advice wanted for transmitter

I am NOT trying to build a radar detector NOR am I trying to build a radar scrambler! I want to build some sort of portable (powered by 9v battery)... low-emittance but effective 'radio wave transmitter' that I can use to set other people's radar detectors off. I have seen other people use these devices on the interstate before and I couldn't help but relish in the sight of the guy flying by doing 90Mph suddenly hitting his breaks because his detector chirped. It can't be too hard to make one of these devices from some Radioshack parts, as I have seen several pocket sized varieties for sale on the internet that unfortunately lacked any instructions. I just don't know how you would produce 9ghz - 30ghz waves from a portable device, if it is even possible. :( If you have any knowledge in this area your help would be appreciated! Thank you.