9
The antennas
Now you need to make two antennas, each of which is suitable for a particular
type of field: an E-field antenna for sensing electrical fields and an H-field
antenna for sensing magnetic fields.
Start with the E-field antenna. All you need for this is a length of
solid insulated wire. Cut the wire included in the kit in the middle to
obtain two pieces approximately 25 cm long. Take one of these and
form a loop in one end. Cover the tip of the wire at this point with a
piece of heat-shrink tubing or electrical tape (see photo). This
insulates the antenna, so that you can easily use the loop to sniff for
noise on a circuit board.
At the other end of the wire, strip off approximately 3 mm of the
insulation and slide the Cinch connector shell over the wire. Solder
the wire to the centre pin of the Cinch connector. Screw the
connector together and straighten the antenna. The antenna is now finished.
Next comes the H-field antenna. For this you will use the coil. Trim the leads of
the coil to approximately 4 mm. Cut two lengths of wire approximately 5 cm long
and strip their ends. Solder one end of each wire to the Cinch connector and
screw the connector together. If you are using heat-shrink tubing, slide a piece
of tubing over each wire. Then solder the wires to the coil leads (the polarity
does not matter) and insulate the bare wire ends and coil leads. The H-field
antenna is now ready for use.
Bear in mind that when you hold the TAPIR in your hand, your body forms part
of the antenna, which may increase the audible hum level.
