Filtenna Designs for Radio-Frequency Front-End Systems : A Structural-Oriented Review

Wireless communication has witnessed rapid developments in the last few decades. To further improve the performance of wireless radio-frequency (RF) systems, emphasis has been given to designing multifunctional modules. The front end of RF systems includes transmitting/receiving antennas integrated with bandpass filters (BPFs). These integrated units are commonly known as filtering antennas or filtennas . The techniques related to designing filtennas have been continuously upgraded in the last couple of years. However, different design constraints are encountered during filtenna implementation, which can be better described in terms of frequency selectivity, bandwidth, high gain, radiation efficiency, polarization, and so on. Therefore, an extensive review has been carried out on integrated filtering antenna structures that were introduced during the last decade. The objective of the article is to present an overview of various approaches adopted to deal with different design challenges. The authors hope that this review exercise will be helpful for RF engineers to get a better understanding on filtenna designs and will encourage young researchers who would like to work in this domain.