Muhammad Fahad Farooqui

3.56-bits/cm Compact Inkjet Printed and Application Specific Chipless RFID Tag

In this letter, a 28.5-bit chipless RFID tag, based on paper substrate and realized using inkjet printing technique is presented. Operating within ultrawideband, the tag occupies a compact size of 2 ×4 cm2. Focusing on applications requiring time and date identification, a novel encoding technique is presented that allows efficient frequency band allocation based on the number of required instances of time and date variables. A figure of merit (FOM) relating coding capacity and tag dimensions coined as code density is also introduced. A systematic design process followed by simulations and verified through measurements reveal a high code density of 3.56 bits/cm2 for the presented chipless tag.

An Inkjet-Printed Buoyant 3-D Lagrangian Sensor for Real-Time Flood Monitoring

A 3-D (cube-shaped) Lagrangian sensor, inkjet printed on a paper substrate, is presented for the first time. The sensor comprises a transmitter chip with a microcontroller completely embedded in the cube, along with a 1.5 λ0 dipole that is uniquely implemented on all the faces of the cube to achieve a near isotropic radiation pattern. The sensor has been designed to operate both in the air as well as water (half immersed) for real-time flood monitoring. The sensor weighs 1.8 gm and measures 13 mm × 13 mm × 13 mm, and each side of the cube corresponds to only 0.1 λ0 (at 2.4 GHz). The printed circuit board is also inkjet-printed on paper substrate to make the sensor light weight and buoyant. Issues related to the bending of inkjet-printed tracks and integration of the transmitter chip in the cube are discussed. The Lagrangian sensor is designed to operate in a wireless sensor network and field tests have confirmed that it can communicate up to a distance of 100 m while in the air and up to 50 m while half immersed in water.

Inkjet-Printed Wideband Antenna on Resin-Coated Paper Substrate for Curved Wireless Devices

A low-cost, inkjet-printed multiband monopole antenna for conformal wireless applications is presented for the first time. The antenna is implemented on a low-cost resin-coated paper substrate which can be used for conformal devices. The antenna developed here is composed of four branch lines on the radiator and three L-shaped slots on the ground plane that help to generate multiple bands without increasing the size of the antenna. The antenna has a compact size, making it suitable for handheld and wearable wireless devices. Details of the inkjet printing fabrication processes and related issues are presented. The antennas were characterized under flat and bent conditions, and the results indicate that the antennas can cover most bands for mobile and wireless applications such as PCS, UMTS, GSM1900, and WLAN.

A Ferrite LTCC-Based Monolithic SIW Phased Antenna Array

In this paper, we present a novel configuration for realizing monolithic substrate integrated waveguide (SIW)-based phased antenna arrays using Ferrite low-temperature cofired ceramic (LTCC) technology. Unlike the current common schemes for realizing SIW phased arrays that rely on surface-mount component (p-i-n diodes, etc.) for controlling the phase of the individual antenna elements, here the phase is tuned by biasing of the ferrite filling of the SIW. This approach eliminates the need for mounting of any additional RF components and enables seamless monolithic integration of phase shifters and antennas in SIW technology. As a proof of concept, a two-element slotted SIW-based phased array is designed, fabricated, and measured. The prototype exhibits a gain of 4.9 dBi at 13.2 GHz and a maximum E-plane beam-scanning of ±28° using external windings for biasing the phase shifters. Moreover, the array can achieve a maximum beam-scanning of ±19° when biased with small windings that are embedded in the package. This demonstration marks the first time a fully monolithic SIW-based phased array is realized in Ferrite LTCC technology and paves the way for future larger size implementations.

A 3D printed helical antenna with integrated lens

A novel antenna configuration comprising a helical antenna with an integrated lens is demonstrated in this work. The antenna is manufactured by a unique combination of 3D printing of plastic material (ABS) and inkjet printing of silver nano-particle based metallic ink. The integration of lens enhances the gain by around 7 dB giving a peak gain of about 16.4 dBi at 9.4 GHz. The helical antenna operates in the end-fire mode and radiates a left-hand circularly polarized (LHCP) pattern. The 3-dB axial ratio (AR) bandwidth of the antenna with lens is 3.2 %. Due to integration of lens and fully printed processing, this antenna configuration offers high gain performance and requires low cost for manufacturing.

A wearable tracking device inkjet-printed on textile

Despite the abundance of localization applications, the tracking devices have never been truly realized in E-textiles. Standard printed circuit board (PCB)-based devices are obtrusive and rigid and hence not suitable for textile based implementations. An attractive option would be direct printing of circuit layout on the textile itself, negating the use of rigid PCB materials. However, high surface roughness and porosity of textiles prevents efficient and reliable printing of electronics on textile. In this work, by printing an interface layer on the textile first, a complete localization circuit integrated with an antenna has been inkjet-printed on the textile for the first time. Printed conductive traces were optimized in terms of conductivity and resolution by controlling the number of over-printed layers. The tracking device determines the wearers position using WiFi and this information can be displayed on any internet-enabled device, such as smart phone. The device is compact (55mm45mm) and lightweight (22g with 500mAh battery) for people to comfortably wear it and can be easily concealed in case discretion is required. The device operates at 2.4GHz communicated up to a distance of 55m, with localization accuracy of up to 8m.

3-D Inkjet-Printed Helical Antenna with Integrated Lens

The gain of an antenna can be enhanced through the integration of a lens, although this technique has traditionally been restricted to planar antennas due to fabrication limitations of standard manufacturing processes. Here, through a unique combination of three-dimensional and two-dimensional inkjet printing of dielectric and metallic inks, respectively, we demonstrate a lens that has been monolithically integrated to a nonplanar antenna (helix) for the first time. Antenna measurements show that the integration of a Fresnel lens enhances the gain of a two-turn helix by around 4.6 dB, which provides a peak gain of about 12.9 dBi at 8.8 GHz. The 3-dB axial-ratio bandwidth of the antenna with the lens is 5.5%. This work also reports the complete characterization of this new process in terms of minimum feature sizes and achievable conductivities. Due to the monolithic integration of the lens through a fully printed process, this antenna configuration offers a high-gain performance by using a low-cost and rapid fabrication technique.

Inkjet printed ferrite-filled rectangular waveguide X-band isolator

For the first time, a rectangular waveguide (RWG) isolator realized through inkjet printing on a ferrite substrate is presented. Yttrium iron garnet (YIG) substrate is used for the realization of the ferrite-filled isolator. Contrary to the substrate integrated waveguide (SIW) approach, all four walls of the waveguide have been inkjet printed on the YIG substrate demonstrating the utility of inkjet printing process for realizing non-planar microwave components. The isolation is achieved by applying an anti-symmetrical DC magnetic bias to the ferrite-filled waveguide which then exhibits a unidirectional mode of operation. The isolator is fed by a microstrip to RWG transition and demonstrates an isolation figure-of-merit (IFM) of more than 51 dB in the operating band from 9.95 GHz to 11.73 GHz with a very high peak IFM of 69 dB. The minimum insertion loss in the operating band is 2.73 dB (including losses from the transitions). The isolator measures 33 mm × 8 mm × 0.4 mm. This work introduces an inkjet printed non-planar microwave device which is easy to fabricate showing the ability of inkjet printing for fabricating complex microwave systems.

Inkjet printed circularly polarized antennas for GPS applications

Two novel, inkjet printed circularly polarized antenna designs are presented for GPS applications. First antenna design comprises a planar monopole which has been made circularly polarized by the introduction of an L-shaped slit. The antenna shows a gain of 0.2 dBi at 1.575 GHz with 3-dB axial ratio bandwidth of 3.8%. The second antenna design comprises a modified monopole in the form of an inverted L and has been termed as circularly polarized inverted L antenna (CILA). The antenna shows a gain of -2 dBi at 1.575 GHz with 3-dB axial ratio bandwidth of 4.1%. Both the antenna designs are attractive for mobile applications.

An inkjet printed near isotropic 3-D antenna with embedded electronics for wireless sensor applications

A 3-D (cube-shaped) antenna, which has been inkjet printed on a paper substrate and integrated with embedded electronics, is presented for the first time. A 1.5λ0 dipole is uniquely implemented on all the faces of the cube to achieve near isotropic radiation pattern. The antenna measures 13mm × 13mm × 13mm, where each side of the cube corresponds to only 0.1λ0 (at 2.4 GHz). Measurements with driving electronics placed inside the cube have shown that the antenna performance is not affected by the presence of embedded circuits. The cube antenna design is highly suitable for mobile sensing applications.