868 MHz, 915 MHz and 955 MHz inverted F antenna (PDF) application note from Texas Instruments:
This document describes a PCB antenna designed for operation in the 868 MHz, 915 MHz and 955 MHz ISM bands. This antenna can be used with all transceivers and transmitters from Texas Instruments, which operates in these frequency bands. Maximum gain is measured to be −0.12 dB and overall size requirements for this antenna are 43 x 20 mm. Thus this is a medium size, low cost antenna solution.
Figure 1 shows a picture of the board being used to develop and characterize this antenna. The board is pin compatible with CC1110 EM and is equipped with two LEDs, a push button, a 10-pin debug connector and a 2-pin power connector for test and characterization purpose.