With the blooming of wireless technologies for communications, fifth-generation (5G) mobile communications have become one of the hottest topics in recent years. For any 5G wireless devices and systems, antennas, filters, amplifiers, mixers, and so forth are crucial components for the RF frontend. However, most conventional designs have difficulty satisfying the stringent requirements of the 5G mobile communications on bandwidth, radiation pattern, size, and cost. For example, antennas and circuits for implantable systems and Internet of Things are desired to be with new frequency band, low profile, compact size, low cost, and easy integration. Thus, the demand for different types of novel and high-performance antennas and circuits is increasing exponentially.

This special issue is intended to propose and discuss the design of microwave and millimeter-wave antennas and circuits regarding the 5G mobile communications. The objective of this special issue is to establish the state of the art for the most relevant problems in RF components and to search for novel efficient concepts and designs in the related areas. It is expected to address and report recent attractive topics in antennas and circuits for the 5G techniques. The desired purpose of the special issue is to make a contribution to 5G mobile communications in both academic and industrial areas. We invite investigators to submit original research articles and reviews to this special issue.

Potential topics include but are not limited to the following:

• Antennas and propagation
• Microwave circuits and systems
• Millimeter-wave technologies
• Electromagnetic theory in wireless systems
• Computational electromagnetics
• EMC in mobile systems
• Advanced processes in microwave and millimeter-wave antennas and circuits
• Antennas and circuits for implantable systems
• Antennas and circuits for car-to-car communications
• Antennas and circuits for the Internet of Things