This letter reports the design and development of a Conductive Bridging RF-Switch with simple fabrication steps without the use of any clean room technologies. The reported device is a fully passive shunt mode RF-Switch on a Co-Planar Waveguide (CPW) transmission line, which operates in the DC to 3GHz range. This particular topology is chosen in contemplation to limitations imposed by the chosen realization process. The device is based on a Metal-Insulator (electrolyte)-Metal (MIM) structure, with Copper-Nafion ®-Aluminum switching layers. S21 switching between-1dB (RF-On) and-16dB (RF-Off) is demonstrated till 3GHz by the device. DC pulses in the range 18V/0.5mA and-20V/0.1A are used respectively to SET and RESET the switch, and the instantaneous power consumed for SET and RESET is respectively 1.7µW and 3mW. The SET and RESET state DC resistance of the switch are observed as 2Ω and 2MΩ subsequently. The model is initially simulated using commercial FEM based Electromagnetic modeling tool and validated experimentally.
In this paper, we investigated the simulation and fabrication of an E-shaped microstrip patch antenna realized on multilayered polyester fabric suitable for WiMAX (Worldwide Interoperability for Microwave Access) applications. The main challenges while designing a textile antenna were to provide adequate thickness, surface uniformity and water wettability to the textile substrate. Here, three layers of polyester fabric were stacked together in order to obtain sufficient thickness, and were subsequently dip coated with polyvinyl butyral (PVB) solution. The PVB-coated polyester fabric showed a hydrophobic nature with a contact angle of 91°. The RMS roughness of the uncoated and PVB-coated polyester fabric was about 341 nm and 15 nm respectively. The promising properties, such as their flexibility, light weight and cost effectiveness, enable effortless integration of the proposed antenna into clothes like polyester jackets. Simulated and measured results in terms of return loss as well as gain were showcased to confirm the usefulness of the fabricated prototype. The fabricated antenna successfully operates at 3.37 GHz with a return loss of 21 dB and a maximum measured gain of 3.6 dB.
We report the design and first results of a Re-Configurable RF-encoding particle (REP) for Chipless RFID tag, based on a Nafion-CBRAM Cell. The developed tag consists of a modified shorted dipole as REP, equipped with a Copper-Nafion ®-Aluminum Metal-Insulator-Metal (MIM) non-volatile Ionic-Bridging switch. The MIM switch is similar to an RC parallel network, which tunes the electrical length of the resonator. The Chipless tags switch between two different resonance frequencies, in the Set and Reset state of the switch. An electrical model is also developed for the REP, to explain the mechanism of switching. The experimental results are in close agreement with the simulated results using commercial EM Simulators. This study is a proof of concept of electronically reconfigurable Chipless tags based on integrated switches which have the potential to be directly printed along with the tag.
A single probe-fed novel V slit, stub and slot embedded circular microstrip antenna with resonances in the three bands of UMTS, worldwide interoperability for microwave access (WiMAX) and WLAN is presented. The polarisation is circular in the UMTS band and linear in the other two bands. Asymmetrical V slits in the patch boundary along with an embedded circular slot in the patch centre are employed to introduce the perturbation necessary for circular polarisation. Impedance bandwidths (BWs) of 4.2, 2 and 6.2%, respectively, in the three bands centred at 2, 3.5 and 5.6 GHz are obtained. The axial ratio BW is 2.3% in the UMTS band. Moderate gains of 4.4, 3.5 and 2.8 dBi are obtained in the three bands. There is a patch size reduction of about 48% when compared with the conventional circular patch antenna at a fixed operating frequency. The radiation pattern is directional in the WiMAX band and nearly omnidirectional in the WLAN band.
Abstract-This paper presents a compact 2.45 GHz single feed directional circularly polarized (CP) microstrip antenna for radio frequency identification (RFID) applications. The proposed antenna comprises a dodecagonal microstrip patch embedded with an irregular polygonal slot, fabricated on an FR4 substrate. Two antennas, one with right-handed circular polarization (RHCP) and the other with left-handed circular polarization (LHCP), both resonating at a frequency of 2.45 GHz are presented. The measurement results show a 3 dB axial ratio bandwidth of 5.5%, a 10 dB impedance bandwidth of 5.7% for both the antennas, a peak gain of 4.82 dBi for RHCP antenna and 4.67 dBi for LHCP antenna. In addition, the antennas provide symmetrical patterns with 88 • half-power beam width. The overall size of the antenna is 50 mm × 50 mm × 1.6 mm and offers an area reduction of 21.17%.
In this article, we present the design and results of an electronically re-writable chipless RFID tag on paper substrate. This tag consists of two resonators build around a modified shorted dipole, integrated with a non-volatile Metal-Insulator-Metal (MIM) switch, which tunes the electrical length of each resonator to resonate at two different frequencies, depending on state of the switch. One can electronically reconfigure the tag using low power DC pulses to change its RF signature. The integrated MIM switch has a layer architecture of Silver-Nafion-Aluminum, formed exclusively using an in-house process in ambient laboratory conditions, notably without the use of any 'clean room' facilities. Operating mechanism of the tag is validated with the help of developed electrical equivalent model. This study proves the concept of realizing 'electronically reconfigurable' chipless tags on flexible and low cost substrates, with a fabrication process compatible with mass production.
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