Browsing by Author "Tzuang, CKC"

Now showing 1 - 20 of 54

38 GHz high-directivity planar leaky-mode antenna array
(2001)
Hung, TP
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
This paper resents a high-directivity planar microstrip antenna array operating at microwave frequency. The antenna array consists of 48 sub-arrays, and each sub-array comprises 4 elements. The radiation mechanism of the single element, by exciting the first higher order mode (EH, mode), can be estimated by the full-wave analysis. Through appropriately arranging and feeding these 192 single elements, the radiated characteristic of the antenna performs narrow radiation beamwidth both in azimuth (AZ) and elevation (EL), thus achieving high directivity. The planar microstrip antenna array prototype is built and tested at 38GHz by traditional printed circuit board (PCB) fabricating process. The measurement result indicates the high directivity of 22.3dB and the 3-dB beamwidth of 8degrees/12degrees (AZ/EL) at the elevated angle 30.2degrees away from the broadside direction.
A broadband microstrip-to-waveguide transition using planar technique
(2001)
Lee, CJ
;
Wu, HS
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
This paper presents a novel methodology, which employs a multi-layer structure to act as an interconnection between microstrip and rectangular waveguide. A Ka-band microstrip-to-waveguide transition consisting of two back-to-back mode converters are designed and implemented on the microwave printed circuit board. The field-matching between the microstrip and the partially filled rectangular waveguide can obtain great scattering characteristics of over 40% bandwidth and low transmission loss of -0.28 dB. These attractive performances indicate that the proposed microstrip-to-waveguide transition can provide a feasible approach to integrate all the RF front-end components in one module by using conventional PCB (printed circuit board) fabrication process.
A circuit-modeling perspective of leaky-mode leakages in a corner-fed square patch
(2002-08-01)
Chen, KC
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
This paper chronicles the leaky-mode leakages in a corner-fed square patch. First, the measured peak RPA (relative power absorbed, 1 - S-11(2) - S-21(2)) values of the two-port corner-fed square patch (two-port test circuit) are reported. These are 21.1%, 52.3%, 89.8% and 81.3% at 5.68 GHz, 11.76 GHz, 16.68 GHz and 22.29 GHz, respectively. Such periodicity of frequencies and the phenomenon of increasing losses at higher frequencies enable us to link these peak frequencies to leaky-mode excitations. The modal spectra of the higher-order leaky modes with a strip width of 630 mil, equal to the side length of the square patch, are obtained by the well-known space-domain integral equation method. The maximum available power gain (G(A,max)), obtained by simultaneously complex conjugate matched impedance at the referenced two ports of the test circuit, depicts that (1) nearly loss-free transmission parameter outside the leaky-mode regions and (2) substantial losses inside the leaky-mode regions. This result suggests that the leaky modes are the main sources causing losses for the two-port test circuit. Furthermore, the valley points of the measured and theoretical G(A,max) are about -7.5 dB, -9.7 dB and -12.0 dB at 10.13 GHz, 16.68 GHz and 22.29 GHz, respectively, and all are in the leaky-mode regions of the modal spectra. The one-port properties of the two-port patch with the second port opened are then investigated. The degenerated (0, N) and (N, 0) modes (N = 1, 2, 3 and 4), calculated by the cavity model method, fall into the strong leakage regions from the first to the fourth higher-order leaky modes. The well-known leaky line's frequency-scanning characteristics also appear in the one-port test circuit, with the angle of the main beam moving from theta = 30degrees to theta = 40degrees as the operating frequency is increased from 22.50 GHz to 23.75 GHz. Lastly, a two-dimensional (2-D) transmission-line model of the one-port test circuit is proposed. This model uses two orthogonal modal currents as excitations to stimulate the corner-fed square patch. At 22.60 GHz, in the fourth higher-order leaky mode (EH4) region, the current distributions obtained by the 2-D transmission-line model closely agree with those of the full-wave simulation. This consistency shows that the damped-oscillation current distributions of the corner-fed square patch at 22.60 GHz are caused significantly by the multiple reflections of the leaky mode. Furthermore, at the resonant frequencies of the patch, the tangled bound-mode resonance of the EH0 mode can enhance the leaky-mode leakages.
A dual-beam micro-CPW leaky-mode antenna
(2000-02-01)
Lin, CC
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
Quasi-planar leaky-mode antenna employing the second higher order leaky mode of even symmetry in its leaky-wave regime has been proposed for a new antenna configuration consisting of a microstrip and a coplanar waveguide (CPW) on both sides of the substrate. The new antenna, also known as the micro-CPW antenna, is directly fed by a CPW line without matching circuit. One particular K-band antenna of 36 mm long [about 2.7 free-space wavelengths (lambda(0)) at 22.1 GHz] shows 5.3% impedance bandwidth for VSWR's less than 2.0 for frequencies between 21.927-23.110 GHz, 11.0-dB antenna gain, and 90.02% efficiency. Detailed analyses show that the dual-beam antenna is linearly polarized along two slanted lines, which lie in the longer axes of the ellipses that approximate the radiation contours. Both theoretical and experimental data for the micro-CPW antenna agree very well for the particular design. The proposed micro-CPW antenna is suitable for active integrated antenna integration at higher microwave and millimeter-wave frequencies.
A fully all-planar integrated Ka-band FSK transceiver module
(2001)
Lee, CJ
;
Hung, TP
;
Lin, SC
;
Wu, HS
;
Tsai, CY
An open RFIC (Radio Frequency Integrated Circuit) architecture employing ACSS (Advanced Coplanar Strips System) guiding technology is presented in this paper. This approach can integrate all the RF front-end components in one module using conventional PCB (printed circuit board) fabrication process. A 10 Mb/s FSK signal is upconverted to 30.18 GHz and 30.28 GHz and broadcasted through a cone-shaped antenna at power level of 10 dBm. The received signal is directly converted to baseband by even harmonic quadrature mixer, which shows a great isolation of 30 dB between RF and LO signal. The measured waveforms of the reported transceiver demonstrate the potential of constructing the wireless system with all-planar integrated circuits.
A novel design for the microstrip leaky-mode antenna array with high-efficiency
(2000)
Hu, CN
;
Tzuang, CKC
;
Chen, SD
;
電信工程研究所
;
Institute of Communications Engineering
A novel design of a closely coupled microstrip leaky-mode antenna array is proposed, built, and tested, showing the gain of 19.35 dB, directivity of 19.8 dB, and overall radiation efficiency of 83%. Detailed analyses and array design are presented for prototyping an eight-element antenna array. Excellent agreement between the theoretical and measured results is obtained.
A periodic microstrip radial antenna array with a conical beam
(2003-04-01)
Chen, KC
;
Qian, YX
;
Tzuang, CKC
;
Itoh, T
;
電信工程研究所
The analysis and design of a microstrip antenna array with a conical beam are presented. The antenna array employs a periodic structure derived from the microstrip on a perforated ground plane. The microstrip antenna array consists of eight leaky lines evenly distributed around a circle. Each line radiates mainly a pair of forward and backward beams, forming a conical beam. The new leaky line design employs the concept of space-harmonic modulation on the EH0 mode launched at the common joint of the antenna array. The scattering and dispersion characteristics of the leaky line are thoroughly investigated. The fact that the perturbation of the antisymmetric holes made by photolithographic etching excites the leaky EH1 mode is theoretically and experimentally validated. Scattering analyses of the surface currents on the microstrip, however, reveal in detail the physical operation of the leaky line. The dispersion characteristics are, thus, established and shown in a Brillouin diagram, indicating the role of each space harmonic, denoted by its complex propagation constant gamma(m,n)(+/-). gamma(m,n)(+/-) represents a traveling-wave component of the nth higher-order spatial component in association with the EHm mode: the superscript, + signifies a forward (backward) traveling wave. For the particular leaky line design, gamma(0)(+),(-1) and gamma(1,0)(+) space barmonics, both showing odd-symmetric field polarization, and both outside the triangular Brillouin region, form the backward and forward leaky waves, respectively. When the leaky lines are evenly and collinearly tied, an 11.5-GHz radial antenna array prototype is formed, and emits a conical beam, showing a 3-dB beamwidth of 24degrees at the flare angle of 31degrees.
Active leaky-mode array and application
(1998)
Chen, SD
;
Hu, CN
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
Recent advance in active integrated microstrip leaky-mode array is presented. Both theory and experiment for assessing the various types of leaky-mode arrays agree very well in prediction of the pencil-beam radiation characteristics and the frequency scanning directions. One successful example of applying the leaky-mode array in the microwave vision system is reported.
All-planar dual-mode asymmetric filters at Ka-band
(2003-03-01)
Chen, HC
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
All-planar dual-mode inductive asymmetric filters utilizing new planar microstrip to dielectric-loaded rectangular waveguide transitions at Ka-band were presented and built in this letter. The conventional, three-dimensional metallic rectangular waveguide dual-mode filters can be implemented into mature PCB technology with a much easier and lower-cost fabrication process on the basis of the all-planar feature of the transition. This work demonstrates two Ka-band filter examples with center frequency at 31 GHz and bandwidth at 1 GHz and 2 GHz. The measured minimum insertion loss of each case was, respectively, 2.68 and 1.12 dB, with greater than 10 dB return loss in the passband. Moreover, the measured side-band attenuation (near passband) is larger than 30 dB due to the transmission zeros at each side of the passband.
An integrated quasi-planar leaky-wave antenna
(1996-08-01)
Chou, GJ
;
Tzuang, CKC
;
交大名義發表
;
電信工程研究所
;
National Chiao Tung University
A new quasi-planar leaky-wave antenna is presented. It consists of microstrip line on one side of the substrate and uniplanar circuit on the other side placed in a partially opened waveguide. The leakage is produced by the excitation of the first higher order (odd) microstrip mode coupled electromagnetically through slotline on the opposite side of the substrate. Theoretic results based on rigorous Green's impedance integral equation method show that the new microstrip-slotline-coupled leaky-wave antenna has broadband tuning range via structure parameters and is Insensitive to microstrip line width variation. Measured relative power absorbed (RPA) results indicate that the useful frequency bandwidth agrees with what rigorous field theory predicts. The measured antenna radiation patterns also agree very well with approximate theoretic computations. Theory and experiments show that the proposed leaky-wave antenna can interface to feeding structure easily and directly, the new antenna may become good candidate for microwave and millimeter-wave integrated antenna design.
Analysis and design of feeding structures for microstrip leaky wave antenna
(1996-09-01)
Lin, YD
;
Sheen, JW
;
Tzuang, CKC
;
交大名義發表
;
傳播研究所
Three arrangements of the feeding structure for the excitation of a microstrip leaky wave antenna are proposed and investigated in this paper, A full-wave spectral domain integral equation method combined with the fundamental mode sampling technique is applied to determine the reflection coefficient of the excitation source. Tabulation technique is used to reduce the computational effort. Dependence on structural parameters such as line width, line spacing and overlap length is fully analyzed to obtain the design criteria for a microstrip leaky wave antenna. Additionally, an experimental setup is used to check the validity of our numerical results and verify the radiation nature of the microstrip line first higher-order mode.
Analysis and design of large leaky-mode array employing the coupled-mode approach
(2001-04-01)
Hu, CN
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
This paper presents the coupled-mode approach to the analysis and design of a large leaky-mode array, in which an N-element microstrip array above a common ground plane supports N coupled leaky modes (leaky EH1 modes) at the first higher order, Following a brief description of a conventional full-wave nonstandard eigenvalue problem for solving the complex propagation constants, we present the detailed formulation of the coupled-mode approach, clearly showing the transformation of the nonstandard eigenvalue problem into a standard one. Thus, all the eigenvalues (complex propagation constants) and eigenvectors (modal current distributions) are solved simultaneously, regardless of the size of the array (N). Two key issues pertinent to the successful implementation of the proposed coupled-mode approach are addressed: the determination of the coupling coefficients and the uniqueness of the isolated uncoupled leaky mode, which represents the leaky modal solution of a single microstrip, but is derived from a system of coupled leaky-mode solutions provided the coupled microstrips have equal width and spacing, Closed-form expressions for obtaining the coupling coefficients of orders two, three, and four are presented. Theoretical studies of closely coupled microstrip arrays of two, three, and four elements show that the magnitude of the coupling coefficient C-i,C-i+j between elements i and i + j decreases at the order of 10(-j). These theoretical case studies also lead to the same isolated uncoupled leaky-mode solution as predicted. Furthermore, the dispersion characteristics of the microstrip array at the first higher order obtained by the coupled-mode approach and the full-wave approach agree excellently for all the case studies, Error analyses indicated that at least two coupling coefficients (C-i,C-i+1 and C-i,C-i+2) are required for obtaining accurate complex propagation constants with rms errors less than 1% for most of the leaky region of the particular array under investigation. An example of applying the proposed coupled-mode approach for analyzing a corporate-fed leaky-mode array of eight elements is reported, revealing that only four out of the eight leaky modes are excited. The coupled-mode theory predicts the far-field radiation pattern in the main beam region in excellent agreement with the measured results.
Applying electric-magnetic-electric (EME) composite metal strips to reduce the size of patch antennas
(2001)
Tsai, CY
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
This paper presents a novel technology to reduce the size of microstrip patch antennas. Utilizing this recently developed periodic structure (EME metal strips), we can increase the slow-wave factor of microstrip lines. This benefit can help us to reduce the size of patch antennas. According to our experimental results, the resonant length and area of the EME patch can be reduced to be 76% and 57% when compared with the conventional one.
Artificially integrated synthetic rectangular waveguide
(2005-09-01)
Wu, HS
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
A synthetic rectangular waveguide (SRW), which consists of two electrical sidewalls and two parallel periodical structures placed at the top and bottom surfaces of the waveguide, is presented. The SRW is made by multilayered integrated circuit processes, which typically have large ratios of SRW lateral dimensions to substrate thickness. Two theoretical methods, finite-element method and deembedding of composite structure consisting of SRW and mode converters, are applied to investigate the propagation characteristics of the SRW. Application of the dispersion characteristics of the two-dimensional periodical structures coupled with appropriate mode converter designs leads to results in SRW designs supporting TE(10), TM(00), and TM(10) modes. Measurements and the two theoretical approaches indicate that the slow-wave factor is 4.9 and Q-factor is 260 at 6.85 GHz for the TE(10) mode propagation with a cutoff frequency of 4.10 GHz (0.348 factor of cutoff frequency of conventional rectangular waveguide using the same material and dimensions). The theoretical data show the TM(00) mode to have a slow-wave factor of 1.8, Q-factor of 187.6 at 11.4 GHz, and cutoff frequency of 10.2 GHz. The TM10 mode has a slow-wave factor of 1.98, Q-factor of 187.6 at 12.5 GHz, and cutoff frequency of 10.4 GHz.
Bound-mode resonance improving the input matching of a dual-mode leaky guiding structure
(1998-12-01)
Lin, CC
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
A novel approach of incorporating the bound-mode resonance in a uniform micro-CPW (coplanar waveguide) line that shows excellent input matching is presented. The matrix-pencil signal analyses of the CPW-fed micro-CPW guide confirm that two modes, namely, the bound CPW mode and the leaky second higher order microstrip mode, dominate, whereas the microstrip mode contributes too little to be detected. Both theoretical analyses and experimental measurements of the CPW-fed micro-CPW guide show that two well-matched input return losses regions are directly related to the resonances of the CPW mode within the guide.
Characteristic impedance and propagation of the first higher order microstrip mode in frequency and time domain
(2002-05-01)
Chen, SD
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
This paper experimentally and theoretically confirms the validity of the definition proposed by Das for computing the complex characteristic impedance of the first higher order (EH1) microstrip mode. The normalized complex propagation constant and complex characteristic impedance of the microstrip obtained by the rigorous full-wave integral-equation method is also presented. To better understand the circuit behavior of the leaky mode at the respective frequencies, the results are analyzed in both frequency and transformed steepest descent. plane. A differential time-domain reflectometry (TDR) experiment shows that the experimental results are in excellent agreement with the time-domain plots obtained theoretically by the inverse discrete Fourier transform of the transmission line modeled by the dispersive characteristic. The propagation characteristics of the echoed signals in the time domain, which are reflected from the open end of the leaky line, are analyzed in detail using the corresponding group velocity of the EH1 mode. The wide spread of the echoed signals in the time domain is the direct result of the highly dispersive group velocity. The slowest group velocity is in the leaky region. The time-to-frequency conversion of the measured TDR data reveals that the reflection, leaky, and propagation zones coexist simultaneously for the EH1 mode propagation. ne conversion also accurately assesses the attenuation constant of the EH1 mode if the attenuation is not too high. The Fourier transform of the TDR responses also simultaneously yields the input reflection coefficient (S-11) and the complex characteristic impedance. The complex characteristic impedance extracted from the TDR responses also agrees closely with the theoretical data.
Characteristic impedance matrix of a suspended microstrip line
(2001)
Chen, SD
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
This paper studies the characteristic impedance matrix of a single suspended microstrip. This peculiar network modeling quantity, completely different from the conventional knowledge about the characteristic impedance matrix of a system of parallel transmission lines supporting quasi-TEM modes, is the result of the coupling of the bound mode and the space-wave-type leaky mode propagating simultaneously on the same guiding structure. Theoretical data show that the two modes are not orthogonal and they couple significantly. The formulation and the codes are validated by checking against the known data. The power-current definition for defining the impedance is adopted. This characteristic impedance matrix is found to be complex and satisfies the necessary and sufficient condition for passivity.
Characteristics and design of broadside-coupled transmission line at a higher order leaky mode
(2003-02-01)
Huang, KFS
;
Tzuang, CKC
;
電信工程研究所
;
Institute of Communications Engineering
The aim of this paper is to provide: 1) a detailed description of the higher order leaky modes of the much-used broadside-coupled microstrips and 2) demonstrate the practical application of such leaky modes as an antenna. A representative broadside-coupled transmission-line structure is examined to elucidate the detail of leakage effects at higher order of multilayered three-dimensional microwave and millimeter-wave circuits. Two-layer cases are analyzed from a physical perspective and the total number of first higher order leaky modes is found to be equal to that of microstrips. One of the two first higher order leaky modes obtained in the two-layer case is weakly attenuated, while the other is strongly attenuated. A high-gain narrow-beam leaky-mode antenna using only the weakly attenuated leaky mode is designed and measured as an application of this broadside-coupled structure, exhibiting a marked beamwidth reduction of 60%. This antenna is the first Yagi-Uda-like array antenna that utilizes the higher order leaky modes of the microstrip, for which the three basic elements-driver, reflector, and director-are stacked in the broadside direction. The attenuation rate can be further reduced by adjusting the strip width of the director. The half-power beamwidth of the leaky-mode antenna applying two-layer broadside-coupled microstrips with a wider top microstrip is measured to be 2.10degrees at 25.20degrees from the broadside at 34 GHz.
Coalesced single-input single-output dual-band filter
(2003)
Chang, CH
;
Wu, HS
;
Yang, HJ
;
Tzuang, CKC
;
電信工程研究所
An experimental proof-of-concept two-terminal single-input and single-output (SISO) 1.7GHz/4.1GHz; dual-band filter is presented. It incorporates the so-call frequency-selective resonators that are composite in structure, cascading a microstrip and microstrip on a two-dimensional periodical surface or the so-called PBG(photonic bandgap) ground plane. The composite resonators add additional degrees of freedom for controlling the relative positions of the passband center frequencies, Thus making the dual-band filters, which essential share one common layout. Measured and theoretical filter characteristics for such coalesced dual-band filter agree excellently, validating the proposed concepts.
Complex modes in a compacted meandered synthetic quasi-TEM line
(2004)
Chen, YC
;
Tzuang, CKC
;
傳播研究所
;
Institute of Communication Studies
This paper investigates the dispersion characteristics of the compacted meandered synthetic quasi-2 TEM line with area totaling 50 x 25 mm(2). The quasi-TEM line, or the so-called complementary-conducting-strips (CCS) transmission line (TL), is formed by a square patch with two connecting arms in the top metal layer and a complementary meshed, two-dimensional, periodical ground plane. Two-port scattering analyses exhibit two stopbands in the CCS TL. The matrix-pencil method is applied to extract the modal behavior and demonstrates that the complex-mode pairs exist in the stopband of the CCS TL. For the first time, we may analyze the dispersion characteristics of the meandered transmission line and adequately explain the formation of the stopband of the CCS TL.