The vast majority of the wireless transceivers designed have focused on medium and long distance transmission ranges. Near-field communication is used by systems operating in low frequency and high frequency (HF) bands, whereas far-field communication is utilized by ultra-high frequency and microwave systems. Most traditional wireless communication systems utilize narrowband architectures. Narrowband architectures are quite popular for all types of wireless communication, including short-distance, low-power systems. With the development of new technologies such as body networks and wearable/paintable computer, a new model of wireless sensor network must be considered. Besides classical radio-frequency (RF) identifications applications, where only a fixed tag-ID is read out, passive RF communication is increasingly used for wireless sensor network–like applications. The design of the low-noise amplifier and the antenna driver is impacted by the impedance level of the chosen antenna, which is a strong function of the type of coupling used and the operating frequency.