CPW-fed Line Research Articles

A Comparative Study of Narrow/Ultra-Wideband Microwave Sensors for the Continuous Monitoring of Vital Signs and Lung Water Level.

This article presents an in-depth investigation of wearable microwave antenna sensors (MASs) used for vital sign detection (VSD) and lung water level (LWL) monitoring. The study looked at two different types of MASs, narrowband (NB) and ultra-wideband (UWB), to decide which one was better. Unlike recent wearable respiratory sensors, these antennas are simple in design, low-profile, and affordable. The narrowband sensor employs an offset-feed microstrip transmission line, which has a bandwidth of 240 MHz at -10 dB reflection coefficient for the textile substrate. The UWB microwave sensor uses a CPW-fed line to excite an unbalanced U-shaped radiator, offering an extended simulated operating bandwidth from 1.5 to 10 GHz with impedance matching ≤-10 dB. Both types of microwave sensors are designed on a flexible RO 3003 substrate and textile conductive fabric attached to a cotton substrate. The specific absorption rate (SAR) of the sensors is measured at different resonant frequencies on 1 g and 10 g of tissue, according to the IEEE C95.3 standard, and both sensors meet the standard limit of 1.6 W/kg and 2 W/kg, respectively. A simple peak-detection algorithm is used to demonstrate high accuracy in the detection of respiration, heartbeat, and lung water content. Based on the experimental results on a child and an adult volunteer, it can be concluded that UWB MASs offer superior performance when compared to NB sensors.

Characterization of Broadband Antenna Based on FR-4 Substrate Material

A simple and compact design of a coplanar waveguide (CPW)-fed broadband square patch antenna is introduced. The proposed broadband antenna is printed on a single-layer PCB with a pair of T-match like symmetric structure which acts as tuning stubs and L−shaped fed-transmission line. The antenna occupies a small radiating area 27.1×8.4 mm2 is demonstrated on an FR−4 substrate PCB with relative permittivity (εr) 4.3, and loss tangent (tan δ) 0.02 and thickness 0.76 mm. The ground plane area of the antenna is 60×60 mm2 with 50Ω CPW-fed line. The designed antenna achieved impedance bandwidth of 100.7%, (1.244 to 3.771) GHz and axial-ratio bandwidth 20.6%, (2.649 to 3.257) GHz respectively, with a return loss <-10 dB (VSWR <2), and axial ratio less than 3−dB respectively. The antenna is simulated using CST V.17 EM Simulator, and the performance of the antenna parameters like return loss, VSWR, axial ratio bandwidth (AR−BW), radiation pattern and surface current density is improvised to an acceptable limit. The analysis of results thus achieved so many similarities between the measured and simulated results

A Compact, Planar, and CPW-Fed Metamaterial-Inspired Dual-Band Antenna

A novel compact, planar, and coplanar waveguide (CPW)-fed dual-band antenna is designed and proposed using composite metamaterial. Such composite metamaterial consists of an inner split-ring resonator (SRR) and an outer closed-ring resonator (CRR). The composite metamaterial can provide dual-band operation at 2.595-2.654 and 3.185-4.245 GHz with reflection coefficient better than -10 dB by the two resonant modes of SRR and CRR, respectively. A CPW-fed line with trapeziform ground plane and tapered impedance transformer line is employed to improve the impedance matching of the antenna. The uniqueness of this design is that the inner SRR with size much smaller than the resonant wavelength is used for obtaining the lower narrow frequency band, which makes the dual-band antenna very compact. Antenna parameters, including reflection coefficient, radiation pattern, radiation efficiency, and gain, are analyzed with numerical simulation and experimental measurement. Good agreement between the simulation and measurement is observed.

Design of Planar Inverted-F Antenna with Wide and Multi Band Characteristic for Mobile Handset

The development of a small and multiband antenna plays an important role in the rapidly growing mobile communication market. This paper presents the design of a novel small and wideband planar inverted F-antenna which simultaneously covers GSM850/GSM900/DCS1900/IMT2000/WLAN/DMB services. The proposed antenna consists of a main patch with a pair of slits and L-shaped patch, occupying a total volume of 15×36×6 mm 3 . A very wide impedance bandwidth characteristic was achieved by optimizing both the gap distance between the feed line and L-shaped patch, and also the lengths and widths of a pair of slits on the main patch, which is excited by the modified CPWfed line. The average gains at the frequencies of 850, 2000 and 2600 MHz were -2.51, -1.42 and -1.68 dBi, respectively. The overall shape of the radiation patterns is suitable for mobile communications.