You and your group are returning from 14 days of DX-expedition on East Kiribati T32.
On the way back you are changing planes in Bangkok. Unfortunately, your luggage gets mixed up at the airport with identical luggage from a ring of drug smugglers (damn all those Samsonite look-alike suitcases).
You have to pick up your own luggage - and not that of the drug smugglers - and pass through customs. But there is no way you can tell the difference from outside - and opening suitcases containing drugs is not something you want to do in Thailand where possession of drugs gives from 10 years in prison to a death sentence.
But there is hope! A mobile phone is left turned on in your luggage, although the ringing tone is disabled. You have some spare components from the expedition in your hand luggage, so maybe you can build a kind of detector. Call the hidden telephone and decide which suitcase is emitting RF energy around 900 MHz when called.
You have about 30 minutes before boarding, and luckily the Bangkok Airport Authorities are sponsoring hot soldering irons.
Build a piece of equipment - field strength meter, RF sniffer, kitchen weight, X-ray machine, crystal ball or ?? - to help finding the right suitcase.
You all have 30 minutes for the construction - no extra points for speed, so make good job. You also have to make a drawing (schematics) and a short description of the machine.
Next you will take turns trying to find the hidden mobile phone from a distance of not lees than ½ meter. If not successful, you are allowed to repeat at closer range - but will lose some points.
Keywords for the equipment are sensitivity and accuracy.
Points will be given for: