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A design of planar rectangular spiral antennas for the wireless vehicle battery charging system operating at 13.56 MHz is presented in this paper. The proposed antennas are designed with low-cost, low-complexity and low-profile constraints. The study is performed by analyzing the power transmission efficiency of the spiral antennas via scattering parameters and associated reflection coefficients....
Conjugately characteristic impedance transmission lines (CCITLs), possessing conjugate characteristic impedances (Z0±) of wave propagating in opposite directions, are implemented using a terminated finite lossless reciprocal periodic structure consisting of a unit cell of 2-section microstrip reciprocal lossless transmission lines (TLs). Numerical simulations show the Z0± magnitudes of 50±0.24% Ω...
In this paper, the multiple sweep method of moments (MSMM) is employed to design non-uniform planar dipole antenna arrays in free space, where the genetic algorithm (GA) is integrated with the MSMM to find optimum array parameters. The antenna design is focused on parameters of non-uniform planar dipole antenna arrays, which are the length of each element, spacing between elements, and the feeding...
This paper proposes the design of a thin-strip on-glass antenna for a DAB automotive application. The proposed antenna uses a triangular thin-strip monopole as a radiating element, including a ground strip matching technique to obtain an improved impedance matching. The antenna radiation pattern, reflection coefficient [∣S11∣ (dB)], polarization, and absolute gain in the operating frequency band are...
In this paper, the use of the multiple sweep method of moments (MSMM) is proposed to design collinear dipole antenna arrays in free space. The genetic algorithm (GA) is cooperated to find the optimum array parameters. The antenna design is focused on non-uniform spacing collinear dipole antenna arrays. Under this appropriate combination (MSMM/GA), numerical results are presented to demonstrate its...
In this paper, the multiple sweep method of moments (MSMM) with the spectral acceleration (SA) algorithm and the genetic algorithm (GA) is proposed to design non-uniform spacing collinear dipole antenna arrays in free space. The SA algorithm is employed to accelerate the MSMM to be O(N), and the GA is incorporated to find optimum array parameters, where N is the total number of unknowns. Under this...
This paper presents a dual frequency band circularly polarized antenna system for Satellite Digital Audio Radio Service (SDARS) and Global Positioning System (GPS) applications. The proposed dual band antenna system consists of two circular patches each having four perpendicular slots for operating in two different frequency bands with left-handed circular polarization (LHCP) for SDARS and a right-handed...
In this paper, the generalized forward-backward (GFB) method is applied to the complex structures mentioned above. There are several schemes in the calculation of the impedance matrix. They all have pros and cons. One scheme may yield a faster computational time per iteration with more iteration to converge, while others may converge in less iteration with slower calculation time per iteration. Numerical...
This paper proposes an antenna using an eight-branch folded strip with a circular parasitic patch on circular ground plane for SDARS applications. The proposed antenna is designed to cover the bandwidth of 2.332-2.345 GHz (SDARS frequency band). The simulation simulation results of the proposed antenna are well-suited for XM Radio SDARS specification. The conical-beam pattern with left-handed circular...
The conjugately characteristic impedance transmission lines (CCITLs) implemented by lossless periodic transmission-line (TL) structures can exhibit active characteristic impedances (negative characteristic resistances). In this case, the magnitude of the voltage reflection coefficient is always greater than or equal to unity for passive load terminations. Due to complicated equations involved with...
This paper presents the RFID tag antenna design for the frequency band of 920-925 MHz corresponding to the standard of UHF RFID in Thailand. An importance for design the tag antenna is that the impedance of the tag antenna must be conjugately matched with the impedance of the IC chip for the maximum power transfer from the tag antenna to the IC chip. The tag antenna can be easily designed and easy...
A bi-characteristic-impedance transmission line (BCITL) model has recently been used to analyze active loaded transmission lines. Interestingly, associated BCITL can exhibit nonreciprocal and amplifying behavior. However, associated formulas are complicated and do not provide much physical insight into the problems. Thus, the graphical tool developed for BCITLs is employed in this paper to analyze...
An in-depth analysis of lossless reciprocal periodic structures of transmission lines (TLs) is presented. Interestingly, it is found that periodic structures can provide both non-negative (NNCR) and negative characteristic resistances (NCR). In addition, the magnitude of the voltage reflection coefficient associated with an equivalent model of periodic structures terminated with passive loads can...
This paper presents a flat spiral rectangular loop gate antenna in walk-through gate installation for improving the distribution of magnetic field in high-frequency radio frequency identification (HF-RFID) systems. The spiral structure can provide the magnetic field distribution to cover desired region in various directions. This antenna is designed as a walk-through gate for the anti-theft application...
The two-rectangular-printed-spiral antenna with U-strip is proposed. The increasing electrical length and impedance matching is performed by using two spiral arms and adding U-strip. There is no ground plane for this antenna structure. The size is relatively small. The measured return loss is -12.435 dB at 433 MHz with 5.455 % bandwidth (428-452 MHz). The measured absolute gain is about -5 dBi. The...
The FB/NSA method is presented to solve for capacitances of planar structures with a single-layered medium. The spectral Greenpsilas function is modified in order to apply the FB/NSA method. Two numerical examples show that the FB/NSA method provides quite accurate results. Since the FB/NSA method is suitable for relatively large problems, further study will focus on the efficiency of the method;...
This paper proposes the compact antenna for server node of wireless sensor network system. The antenna parameters are varied to achieve the nearest horizontally polarized omnidirectional pattern. The overall antenna width, length and height are fixed for suitable installation. The antenna structure is simple and its design is straightforward. The return loss, radiation pattern, absolute gain and cross-polarization...
The noise considerations for a design of potentially unstable microwave transistor amplifier integrated with CCITLs are investigated. The bilinear transformation, with a verification using the CC approach, is employed to map graphical solutions from the Z0 system into the CCITL system. The magnitude of Fi decreases rapidly with GA, especially for larger phi, and more slowly as GA approaches MSG for...
This paper presents a method to measure the characteristic impedances and propagation constant of bi-characteristic-impedance transmission lines (BCITLs). The derived expressions for determining the BCITL parameters via measurements are provided. An example of BCITLs is given for both passive (Re{Z0plusmn} ges 0) and active characteristic impedances (Re{Z0plusmn} < 0), where Z0plusmn are the...
This paper presents effects of ruminal magnets in the vicinity of a bolus tag of an LF-RFID (low frequency-radio frequency identification) system. The study on effects of ruminal magnets to the communication for an RFID reader and a bolus tag is performed by the resonant-frequency measurement. From measurement results, it is found that effects of ruminal magnets in the vicinity of a bolus tag are...
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