Electrically Small Antennas for Maritime Wireless Applications

Abstract

The maritime wireless communication requires robust radio links and high throughputs for effective and reliable connectivity and networking between various vessels and offshore units. The design and development of antennas for such applications require various complex considerations to meet not only the specific application requirements but also to ensure the performance requirement within a multitude environment and compact antennas with low weight and small form factors are required. Moreover, efficient antennas are needed both at transmitter and receiver for reliable wireless links for various frequencies. However, at low operating frequencies, like VHF band, the size of the antenna is very large resulting from high operating wavelength. Such large size of antenna and its resulting weight restricts the deployment of antennas on ships and vessels etc. This necessitates the design and implementation of small, low weight and efficient antennas or apertures preferably with beam-switching or beam-scanning capabilities for efficient transmission and reception of radio signals across the required bandwidth and beamwidth for effective communication, navigation and surveillance etc. For the lower frequency bands, the dimensions of antennas become very large due to longer wavelengths. By reducing the dimensions of antenna to large extent compared to operating wavelength, it becomes electrically small antenna (ESA). Such ESA suffers from narrow impedance bandwidth due to wide variations in port impedance and low radiation efficiency resulting from reduced radiation resistance. This article will discuss the design and measurement challenges and solutions for electrically small antennas and various design versus performance trade-offs and characterization challenges for ESAs will also be discussed.