ISM Band Wireless Communication Research Articles

A wideband circularly polarized S ‐shaped slot antenna

This article introduces a simple wideband circularly polarized (CP) S-shaped slot antenna for ISM band wireless communication applications. By using a wide curve S-shaped slot patch on the top side and a T-shaped feeding line on the bottom side of the substrate, the wideband CP wave is generated. The overall size of the proposed antenna is 0.85λ × 0.85λ × 0.011λ (λ is the wavelength of the lowest operating frequency) and it has a broad impedance bandwidth of 68.1% between 1.66 and 3.44 GHz for S11 < –10 dB and a 3 dB axial-ratio bandwidth of 57.1% between 1.68 and 3.06 GHz. Within the axial-ratio bandwidth, the measured gain of the proposed antenna ranged from 2.1 to 5.4 dBic. The measured results are in good agreement with simulated results. The new type of slot antenna with wide bandwidth and simple structure is a good candidate for various RFID applications.

Design and realization of novel frequency selective surface loaded dielectric resonator antenna via 3D printing technology

AbstractOne frequently addressed technique for the performance enhancement of radiating elements in the form of microstrip antennas is the utilization of dielectric resonators. A dielectric resonator antenna (DRA) has a conventional structural formation similar to any microstrip patch antenna where, at least, one additional dielectric layer has been placed over the radiating element. In this paper, it is aimed to propose a high performance, easy to prototype, light weight, and low cost DRA in combination with frequency selective surfaces (FSS) for ISM band applications using 3D printing technology. The proposed 3D printed FSS loaded DRA has a measured gain of 5.6 dBi with S11 level less than −10 dB in the operation band between 1.98 and 2.68 GHz. Furthermore, the measured performance of 3D printed antenna is compared with the counterpart alternative antenna designs in the literature for the similar application fields. The novel FSS loaded DRA is not only much smaller than the counterpart antenna designs but also has a moderate gain characteristics which makes the proposed antenna design an optimal RF solution for ISM band wireless communication applications.

A metasurface-based slit-loaded wideband circularly polarized crossed dipole antenna

A metasurface-based low-profile crossed dipole antenna with wide circularly polarized bandwidth for 2.45 GHz ISM band wireless communications is proposed and fabricated in this article. Consisting of four slit-loaded rectangular patches, the double-sided printing crossed dipoles are fed by a pair of vacant-quarter printed rings which circularly polarized (CP) radiation could be generated. With slits loaded, by properly combining the fundamental mode of the two inverted L-shaped dipole, the slot mode and extra resonance generated by the AMC surface, a wideband circularly polarized operation can be obtained. After optimization, the final design with an overall size of 0.44λ0 × 0.44λ0 × 0.1448λ0 at 2.4 GHz had measured a 31.6% (2–2.75 GHz) impedance bandwidth and 3 dB axial ratio bandwidths of measured were 23.2% (2.1–2.65 GHz), respectively. In addition, the antenna performed a small gain variation (7.0–7.5 dBic) and a front-to-back ratio (FBR) of over 25 dB across the whole CP region.

A Wideband Circularly Polarized Cross-Dipole Antenna

This letter introduces a wideband circularly polarized (CP) cross-dipole antenna fabricated on a double-layered printed circuit board (PCB) substrate for 2.45-GHz ISM band wireless communications. Unlike conventional cross-dipole antennas, the proposed cross dipole is designed with wide open ends such that both impedance and axial-ratio (AR) bandwidths are enhanced. In addition, to excite the CP radiation effectively, a curved-delay line providing an orthogonal phase difference among the cross-dipole elements is attached at the corners of the sequentially rotated elements. By choosing a proper radius of the curved-delay line, a wide input impedance of the antenna can be realized. The antenna is center-fed by a 50- Ω coaxial cable and is placed above a square reflector to obtain a directional CP radiation pattern. With the advantage of centered feed, symmetric CP radiation patterns can be achieved across the entire operating bandwidth. Simulated and measured results confirm the proposed antenna produced good CP characteristics. An impedance bandwidth (for VSWR ≤ 2) of about 50.2% (1.99-3.22 GHz) and the 3-dB AR bandwidth of about 27% (2.30-2.9 GHz) around the center frequency of 2.45 GHz were measured. The antenna has an average CP gain of 6.2 dBic across the operating bandwidth and the maximum gain of 6.8 dBic at the center frequency. The size of antenna is 0.45λ×0.45λ×0.24λ.

Compact 5.8-GHz bandpass filter using stepped-impedance dielectric resonators for ISM band wireless communication

High-permittivity dielectric ceramics MgTiO3-CaTiO3 (ϵr ∼ 20) is applied in the fabrication of 5.8-GHz stepped-impedance resonator (SIR) microwave ceramic bandpass filter. Tapped input/output ports are designed to provide a direct connection between the filter and the microstrip transmission line. The microwave bandpass filter is constructed by using two stepped-impedance quarter-wavelength coaxial dielectric resonators. The direct-coupling method was employed in the transformation of electromagnetic energy. Losses and other electromagnetic (EM) effects are taken into account to further modify the actual dimensions of the designed filter. The fabricated bandpass filter achieves an excellent microwave-frequency response with insertion loss of less than 1 dB at 5.8 GHz. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 44: 421–423, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20654

Numerical computation of fat layer effects on microwave near-field radiation to the abdomen of a full-scale human body model

Numerical computation results of fat layer effects on the microwave near field radiation to the abdomen of a three-dimensional (3-D) full-scale human body model are presented. The human body is modeled as a 3-D homogeneous muscle phantom with a fat layer covering the abdomen part. The dipole wire-antenna located proximate to the abdomen is used as the microwave radiation source at 915 MHz. This is to study the effects on hyperthermia heating by using the microwave applicator (at 915 MHz) or the near-field exposure from the proximate handset antenna to the human body at ISM band wireless communication band (902-928 MHz). Coupled integral equations (CIE) and the method of moments (MoM) are employed to numerically compute electromagnetic (EM) energy deposition specific absorption rate (SAR) from the radio frequency (RF) antenna applicator into the proximate fat layer covered abdomen. The antenna input impedance (proximate to the body), return loss (RL), and the resonant antenna length (proximate to the body) will also be numerically determined to increase the microwave power delivered into the body. The study of fat layer effects is important for microwave hyperthermia applications. It is also important for the investigation of the potential health hazard from the near-field radiation of a wireless communication antenna.