RFDesign RFDFLEX1 900MHz Flexible PCB Antenna (300mm RPSMA)
This is one of the lightest and slimmest antennas on the market - Suitable for the 900 MHz ISM band.
It is designed to operate in free space, or stuck onto a relatively RF transparent material, eg. Foam wing, fuselage, balsa wing, thin fiberglass.
It has better than -10dB return loss when in free space, or stuck on a thick slab of EPP foam.
Use of this antenna is easy, as it has integrated feed point matching, an integrated balun for feed cable isolation and black solder resist with gold plated pads for soldering.