Mohd Ifwat Mohd Ghazali

Affordable 3D printed microwave antennas

In this paper, a variety of 3D printed microwave antennas are presented including wide band, narrow band, multiband and reconfigurable designs. In particular, single layer patch, folded E-patch, a bilateral Vivaldi, Spartan logo and Lego-like assembled antennas are demonstrated. 3D printing provides significant flexibility in the design of antennas that combine the assembly of both dielectric and metal layers to achieve desired performance characteristics such as resonant frequency and radiation pattern. Also, small Lego-like blocks can be printed that allows in the design and assembly of novel antennas structures using a combination of dielectric and metal coated blocks.

Affordable terahertz components using 3D printing

This paper presents the design and characterization of 3D printed photonic crystal filter (quasi optic component) and dielectric ridge waveguide (integrated component). Commercially available 3D printer was used to print polymer based components. Design and characterization of these devices is carried out over a frequency range of 0.15 - 0.5 THz. The photonic crystal filter shows a stop band from 0.25 - 0.35 THz. Also a very narrow defect mode (notch filter) was introduced by altering the structure of photonic crystal. The dielectric ridge waveguide shows broadband THz propagation characteristics. The transmission loss was determined to be largely dominated by the loss characteristics of the polymer material used.

Demonstration of RF and Microwave Passive Circuits Through 3-D Printing and Selective Metalization

The ultimate goal of this paper is to print radio frequency (RF) and microwave structures using a 3-D platform and to pattern metal films on nonplanar structures. To overcome substrate losses, air core substrates that can readily be printed are utilized. To meet the challenge of patterning conductive layers on complex or nonplanar printed structures, two novel self-aligning patterning processes are demonstrated. One is a simple damascene-like process, and the other is a lift-off process using a 3-D printed lift-off mask layer. A range of microwave and RF circuits are designed and demonstrated between 1 and 8 GHz utilizing these processes. Designs are created and simulated using Keysight Advanced Design System and ANSYS High Frequency Structure Simulator. Circuit designs include a simple microstrip transmission line (T-line), coupled-line bandpass filter, circular ring resonator, T-line resonator, resonant cavity structure, and patch antenna. A commercially available 3-D printer and metal sputtering system are used to realize the designs. Both simulated and measured results of these structures are presented.

RFID Compatible Sensor Tags for Remote Liquid Sample Interrogation

In this paper, a passive harmonic generator based wireless sensor for long range interrogation of small liquid samples is demonstrated. A step by step method for development of the harmonic doubler based sensor is presented. Two different sensor designs are evaluated for liquid sensing. The first sensor is a T-line resonator coupled to patch antennas and harmonic doubler. The second sensor is a compact design in which a split ring resonator is directly coupled to a dipole antennas based diode doubler. The resonators are loaded by the liquid samples that in turn induce changes in reflected power from the tag. The sensors are evaluated for their remote interrogation capabilities of sensing different liquids under test. Liquid samples measured include mixtures of isopropyl alcohol-water, methanol-water and glucose-water samples. These mixtures provide a range of dielectric properties for the evaluation of the long range sensor. This sensor holds good for potential application in food safety, bio sensing and hazardous chemicals monitoring and detection.

3D printed metalized-polymer UWB high-gain Vivaldi antennas

This paper introduces a UWB high gain Vivaldi antenna fabricated with a polymer-based 3D printer. 3D printing technology allows for simple fabrication that is easier, faster, and lower cost compared to traditional microfabrication and metal fabrication techniques. Two 3D printed designs are presented, the first of which is a simple Vivaldi notch antenna with a radiating slotline cavity. The second design consists of a bilateral Vivaldi with a partially covered cavity, which increases the bandwidth and gain of the antenna. Both designs are printed with an acrylic-based polymer, blanket metalized with a thin copper layer, and fed with a 50 Ω coaxial feed. Both antennas show an extremely wide bandwidth of approximately 14 GHz from 4 to 18 GHz. In addition, the maximum gain of the antennas is approximately 12 dB. The measured results match well with the simulated results, showing the potential for these antennas as low cost, wideband, high gain alternatives which could be used in modern UWB communication systems.

Embedded Passive RF Tags towards Intrinsically Locatable Buried Plastic Materials

This paper demonstrates the use of passive harmonic tags (transponder) as markers for buried plastic pipes. The tag design is based on a double slot antenna that can be buried in the plastic pipes during manufacturing. Design and measurement results are presented for two tag designs: one with a metal backing and one without. The tags are embedded in a plastic casing representing the walls of the plastic pipes. The tag operates at a fundamental frequency (fo) of 2.5 GHz with a return signal (2fo) of 5 GHz. Use of harmonic tags eliminates the clutter from the surface of the ground and thus enhances signal to noise (S/N) ratio of the return signal without the use of filters. The antenna is linearly polarized and polarization can be used as a marker for the direction of the buried pipes. The tag design is compact and can also readily be interrogated using simple hand-held radar units.

Monitoring and localization of buried plastic natural gas pipes using passive RF tags

A passive harmonic radio frequency (RF) tag on the pipe with added sensing capabilities is proposed in this paper. Radio frequency identification (RFID) based tagging has already emerged as a potential solution for chemical sensing, location detection, animal tagging, etc. Harmonic transponders are already quite popular compared to conventional RFIDs due to their improved signal to noise ratio (SNR). However, the operating frequency, transmitted power and tag efficiency become critical issues for underground RFIDs. In this paper, a comprehensive on-tag sensing, power budget and frequency analyses is performed for buried harmonic tag design. Accurate tracking of infrastructure burial depth is proposed to reduce the probability of failure of underground pipelines. Burial depth is estimated using phase information of received signals at different frequencies calculated using genetic algorithm (GA) based optimization for post processing. Suitable frequency range is determined for a variety of soil with different moisture content for small tag-antenna size. Different types of harmonic tags such as 1) Schottky diode, 2) Non-linear Transmission Line (NLTL) were compared for underground applications. In this study, the power, frequency and tag design have been optimized to achieve small antenna size, minimum signal loss and simple reader circuit for underground detection at up to 5 feet depth in different soil medium and moisture contents.A passive harmonic radio frequency (RF) tag on the pipe with added sensing capabilities is proposed in this paper. Radio frequency identification (RFID) based tagging has already emerged as a potential solution for chemical sensing, location detection, animal tagging, etc. Harmonic transponders are already quite popular compared to conventional RFIDs due to their improved signal to noise ratio (SNR). However, the operating frequency, transmitted power and tag efficiency become critical issues for underground RFIDs. In this paper, a comprehensive on-tag sensing, power budget and frequency analyses is performed for buried harmonic tag design. Accurate tracking of infrastructure burial depth is proposed to reduce the probability of failure of underground pipelines. Burial depth is estimated using phase information of received signals at different frequencies calculated using genetic algorithm (GA) based optimization for post processing. Suitable frequency range is determined for a variety of soil with differ...

3D Printed Out-of-Plane Antennas for Use on High Density Boards

This paper presents out-of-plane antenna designs for use on high density boards. These antennas are fabricated using 3D plastic printing (additive manufacturing) and subsequent metallization. Various out-of-plane microwave structures including a transmission line, vertical mount microstrip patch antenna, elevated patch antenna, air-lifted patch antenna, and a monopole antenna are demonstrated. These antennas can be integrated directly on packaged chips or mounted vertically on high density electrical boards. Metal patterning on these non-planar structures is carried out using a damascene like process. Details of simulation, fabrication, and measurements are presented.

A Nonlinear Transmission Line Based Harmonic RF Tag

This paper describes the design and development of a nonlinear transmission line based passive RFID tag. When the tag receives a signal from the interrogator, it generates harmonics which are transmitted back to interrogator. The reflected signal is distorted in time domain due to the harmonic contents. Hence, a change in the rise time would be observed in the received signal. Experimentally, a decrease in rise time by 14% is demonstrated using the wireless tag at a distance of 100mm from the interrogator. The tag was designed to operate in the range of 100 MHz to 500 MHz with Braggs cutoff frequency of 1.2 GHz. This circuit will find applications in tagging, tracking and sensing.

3-D Printed Air Substrates for the Design and Fabrication of RF Components

This paper presents the fabrication and characterization of radio frequency (RF) and microwave passive structures on an air substrate using additive manufacturing (3-D printing). The air substrate is realized by 3-D printing RF structures in two separate pieces and snapped together face to face using a LEGO-like process. Spacers printed on the periphery provide the desired air substrate thickness. Metal patterning on nonplanar printed plastic structures is carried out using a damascene-like process. Various RF structures such as low dispersion transmission line, T-line resonator, high-gain patch antenna, slot antenna, and cavity resonator are demonstrated using this process. Good performance is achieved; for example, measured 50-