You Chung

Design of implantable microstrip antenna for communication with medical implants

The objective of this paper is to design a microstrip patch antenna for communication with medical implants in the 402-405-MHz Medical Implant Communications Services band. Microstrip antenna design parameters are evaluated using the finite-difference time-domain method, and are compared to measured results. The effects of shape, length, size, location of feed point and ground point, substrate and superstrate materials, and their thicknesses are evaluated. An extensive study of the performance of the antennas to changes in these parameters was undertaken. The results of this paper provide guidance in the design of implantable microstrip antennas.

Amplitude and Phase Adaptive Nulling With a Genetic Algorithm

This paper introduces amplitude and phase nulling with a genetic algorithm with the intent of finding the optimum number of LSB of control needed to place multiple nulls while not significantly distorting the far field pattern. Many interference scenarios were modeled and individual runs were averaged to conclude that five LSB of amplitude and three LSB of phase control out of a total of eight bits are best for the linear array modeled. Representative samples of some of the interference scenarios modeled are shown.

Mixed-signal reflectometer for location of faults on aging wiring

Location of faults on aging cables is of great interest to maintainers of aircraft, cars, power distribution systems, communication systems, etc. One class of methods for locating faults is frequency domain reflectometry (FDR), using sine waves as the forcing function. A new frequency domain method called mixed-signal reflectometry (MSR) is described in this paper and compared to data from phase detection FDR (PDFDR) methods. The MSR is less expensive and smaller than the PDFDR and has very similar performance. A prototype system using the 100-200-MHz bandwidth with 256 40-kHz steps is shown to have a resolution of about 10 cm, very similar to a PDFDR in the same frequency band.

Broadband and Multiband Antenna Design Using the Genetic Algorithm to Create Amorphous Shapes Using Ellipses

A method is demonstrated for generating compact, broadband and multiband antennas using ellipses to create new amorphous shapes with greater bandwidth and less return loss that previously demonstrated. Four designs are presented including a tri-band patch antenna optimized for low reflection loss at 1.6, 1.8, and 2.45 GHz. A broadband patch is designed for 1.9-2.1 GHz. A dual-band design embedded in a dielectric is created for use at GSM frequencies, and a broadband monopole is created that operates from 2-6 GHz with low reflection loss. The genetic algorithm is used to optimize the designs. FDTD is used to simulate the designs allowing a low reflection loss design embedded directly into a heterogeneous structure or dielectric material

Wearable UHF RFID tag antenna design using flexible electro-thread and textile

The flexible electro-thread UHF RFID tag antenna has been designed using T-matching method. The antenna size is compact than conventional dipole antenna and reading range is about 2.4 m, better than conventional UHF RFID tags made with copper. The future works are the optimizing size to have better reading range, and finding applications of fabric and electro-thread tag antennas.

Design of a UHF RFID fiber tag antenna with electric-thread using a sewing machine

An RFID tag antenna with electric-thread using a sewing machine is proposed. The characteristics of the electric-thread used as tag antenna are studied and the changes of conductivity for different sewing methods are analyzed. The electro-thread tag antenna is designed by the shape of alphabet characters. The radiation efficiency is about 33% and the measured maximum reading range is about 2.5m in an anechoic chamber. It is demonstrated that the electro-thread is possible to be directly applied to clothes as a brand or company marks. However, it is necessary to develop some additional technology for packaging to protect a tag chip from laundry and wrinkle.

Optimization of a buried microstrip antenna for simultaneous communication and sensing of soil moisture

Imbedded microstrip antennas have been previously demonstrated for use either as sensing elements or as components of a wireless communication system. This paper presents a method and dual use designs for simultaneous sensing of soil moisture and communication from the buried antenna to an external receiver. Using the genetic algorithm and the finite-difference time domain (FDTD) method, the sensing band is designed to have maximum sensitivity to the moisture of the surrounding soil, while the communication band is designed to have minimal detuning due to changes in soil moisture. Single layer and stacked microstrip antennas are shown

Adaptive nulling with spherical arrays using a genetic algorithm

Spherical arrays are arrays that conform to the surface of a sphere. One approach to a spherical array layout is to mold a planar array to the surface of a sphere (spherical-planar array). Another approach is to create circular arrays about the spherical surface (spherical-circular array). This paper presents an approach to adaptive nulling with either type of spherical array using a genetic algorithm. Amplitude and phase adaptive nulling with a genetic algorithm generates deeper and faster nulls than phase-only nulling. A genetic algorithm is used to place a null at the sidelobe of two types of spherical arrays. The 16/spl times/6 element, 256 elements, rectangular grid half wavelength spaced spherical planar array, and the spherical-circular array with same number of elements as the spherical-planar array are simulated and compared.

Capacitance and Inductance Sensor Circuits for Detecting the Lengths of Open- and Short-Circuited Wires

The length of an open- or short-circuited wire is linearly proportional to the capacitance or inductance of the wire, respectively. Several types of simple and inexpensive circuits are introduced to measure these values. Open-circuited (capacitance) measurements are very effective. Short-circuited (inductance) measurements are more difficult, and not all of the circuits worked well. A 555 timer circuit was found to have the best overall performance to locate the ends of both open- and short-circuited wires. The capacitance and inductance values of various types of aircraft wires were measured and verified with analytical equations.

Various wearable embroidery RFID tag antenna using electro-thread

Various embroidery tag antennas shaped like Korean alphabet shape and YJ kindergarten logo shape UHF RFID tag antennas have been designed with 70 D, 100 D and 200 D of electro-thread. The two structures have T-matching structures. The conductivities of three different electro-threads are measured. The measured and calculated resistance values of electronic-threads are used for the simulation. The Korean alphabet UHF RFID tag antenna has 1.5 m reading range. The second design, YJ kindergarten logo shape has been designed with 100 D electro-thread and with two different sewing directions. The reading range with the second tag with horizontal sewing direction achieves 30 cm which is 10 cm longer than that of vertical sewing method. The simulation of embroidery tag antenna with electro-thread requires the resistance value of embroidery itself instead of resistance value of the electro-thread. The different shape of embroidery tag antenna will be designed and the bonding method between electro-thread and RFID chip or strap should be studied.