Here is the breakout board for the RFM22B which gives you access to the pins. The RFM22B is a low-cost ISM (industrial, scientific, and medical) FSK (frequency-shift keying) transceiver module which offers communication at 434MHz and adjustable output power of up to +17 dBm. The wide operating voltage range of 1.8–3.6 V and low current consumption makes the RFM22 an ideal solution for battery powered applications.
Communication with the RFM22B is achieved via a standard 4-wire SPI interface. Three configurable general purpose I/Os are also available, the use of which can be tailored towards the needs of your project. A host of other features are also available including an 8-bit ADC, temperature sensor, RX and TX FIFOs, and low-battery detection. See the datasheet below for a complete description of every register and command.
In our testing, a 17cm wire attached to the 'ANT' pin worked just fine. A hole is drilled next to the 'ANT' pin for strain relief.