Design of a coupled line feed structure for the wideband characteristic of a mobile internal antenna

Abstract

A method to design an adjustable wideband impedance matching structure based on the impedance transformer concept is proposed in order to enhance wideband impedance matching. The designed coupled line feed structure (CLFS) provides a wide impedance characteristic via an operating principle similar to that of an impedance transformer. The CLFS enables tuning capability for the impedance characteristic of an inverted-F antenna (IFA) through adjustments in the line width and gap between the two CLFS spirals. By adding the proposed CLFS to the antenna feed, the bandwidth of the original IFA can provide about 22% wider coverage when compared with an IFA alone, especially over the LTE band, without changing the original antenna design. For frequencies below 1100 MHz, the impedance bandwidth of an IFA is about 40% at a center frequency of 862 MHz.

Inkjet‐printed UHF RFID tag based system for salinity and sugar detection

“…The basic structure of the proposed RFID sensor tag is slot‐match configuration, which provides a good inductive reactance on the surface of high permittivity dielectrics such as water. The tag is designed and optimized based on three main aspects: (1) electrical properties: electrically small with impedance match covering US RFID band (902‐928 MHz), (2) sensing features: Only provides a suitable read range and good impedance match with RFID chip on water bottle surface, (3) fabrication cost: low‐cost and inkjet printed, which is suitable for large‐scale usage.…”

“…Normally, the performance of UHF tags is seriously degraded near vicinity of water or high permittivity liquids. So, to mitigate water effects, the tag is designed using slot‐match technique, which provides a high inductive reactance both in free space and on the surface of the water. Moreover, the dimensions of the tag are optimized to work properly after mounting on plastic bottles having pure water (without any manual addition of salt and sugar).…”

Small‐size adjustable LTE/WWAN coupled‐fed loop antenna for mobile handset applications

“…To support LTE/WWAN dual‐systems, the impedance bandwidth of the embedded internal handset antennas should cover the LTE Band17/13/20/7 (704–746, 746–787, 791–862, 2500–2690 MHz) operating bands besides the traditional GSM850/900/1800/1900/WCDMA Band1 (824–960, 1710–2170 MHz) operating bands. For this application, a variety of promising multiband LTE/WWAN handset antennas have been reported in published papers . However, there is a design challenge for these internal LTE/WWAN antennas to be applied in the handheld devices, especially in the slim smartphones, because of the very limited internal spaces available in the smartphones for using the internal antennas.…”

A compact antenna for 4G mobile handset

“…It is very important for the antenna of personal mobile communication device to be with small size and many operating bands. In the last two decades, to realize the miniaturization and multifrequency, many design schemes have been proposed by researchers . More recently, after the release of 4G, it receives much attention and developed widely and rapidly, due to its properties of low‐power consumption, support of high data rate and simple configuration.…”