Planar Antennas for Reliable Multiband RF Communications

Abstract

Multiband functionality in antennas has become a fundamental requirement to equip wireless devices with multiple communication standards so that they can utilize the electromagnetic spectrum more efficiently and effectively. This is necessary to ensure global portability and enhance system capacity. To meet these requirements, microstrip technology is increasingly being used in communication systems because it offers considerable size reduction, cost-effectiveness as they can be easily manufactured in mass production, are durable and can conform to planar or cylindrical surfaces. Unfortunately, such antennas suffer from intrinsically narrow bandwidth. To overcome this deficiency, various techniques have been investigated in the past. In this chapter, a novel approach is presented to design antennas for applications that cover radio frequency identification (RFID) and WiMAX systems.

Wideband planar array antenna based on SCRLH-TL for airborne synthetic aperture radar application

“…Operating bands chosen for the CP-SAR are: UHF (300 MHz and 850 MHz), L-band (1.5 GHz), S-band (2.4 GHz, 3.15 GHz and 3.8 GHz), and C-band (4.15 GHz). The long wavelengths at UHF should enable the radar to penetrate the foliage and image features on the Earth surface as well as detect underground facilities [11]. To ensure circularly polarized transmit and receive signals the bandwidth of the proposed CP-SAR antenna needs to ensure low axial-ratio (AR).…”

“…These disadvantages make microstrip antennas unsuitable for SAR systems. Hence, several bandwidth enhancement techniques have been reported in literature including utilization of: (1) parasitic patches [8]; (2) near resonant aperture with thick antenna substrate [9]; stacked patches where a parasitic element is placed above a lower patch [10]; and composite right/lefthanded transmission-lines (CRLH-TLs) [11]- [15]. Bandwidth and radiation efficiency enhancement in the case of using CRLH-TL structures can be achieved by simply using a thicker substrate with lower dielectric constant [9].…”