Magnetic Wall Cavity Research Articles

Wide Impedance-Bandwidth and Gain-Bandwidth Terahertz On-Chip Antenna With Chip-Integrated Dielectric Resonator

A wide impedance-bandwidth and gain-bandwidth terahertz (THz) on-chip antenna (OCA) with chip-integrated dielectric resonator (CIDR) backed by a ground plane is proposed in this article. The antenna uses the inherent silicon substrate in complementary metal-oxide-semiconductor (CMOS) technologies as a rectangular dielectric resonator (DR), that is, the CIDR. This CIDR can be seen as a standard dielectric resonator antenna (DRA) or a magnetic wall cavity with in-phase reflected waves from the ground. A versatile comb-shaped dipole antenna is designed above the silicon CIDR, functioning both as a feeder for the DRA and an independent radiator. With the proper design of the CIDR and the dipole, multiple higher order DR modes and the cavity mode are simultaneously excited, namely, hybrid DR-cavity modes. The hybrid modes greatly expand the bandwidth and improve the gain. Simulations show that the -10 dB impedance bandwidth and 3 dB gain bandwidth are 50% and 34.5%, respectively, while a peak gain of 6.5 dBi is achieved at 305 GHz. For validation, the antenna is fabricated using the Taiwan Semiconductor Manufacturing (TSMC) 65 nm CMOS technology and tested by dedicated THz measurement setups. The fabricated sample shows a peak gain of 8.6 dBi and a maximum radiation efficiency of 44% at 295 GHz. Meanwhile, low cross-polarization levels and stable patterns are also observed. The features of wide bandwidth, high gain, and low profile make the antenna a good candidate in fully integrated THz transceiver systems. To the best of the authors' knowledge, this is the widest fully integrated OCA working at THz frequencies.

An efficient study of circular microstrip antenna on suspended and composite substrates

In this paper, an efficient full-wave analysis of a circular microstrip patch printed on suspended and composite substrates is performed using a dyadic Green’s function formulation. Galerkin’s technique is used in the resolution of the integral equation of the electric field. The TM set of modes issued, from the magnetic wall cavity model, are used to expand the unknown currents on the circular patch. The radiation patterns are expressed regarding the transforms of the currents. The convergence of the method is proven by calculating the resonant frequencies, half-power bandwidths, and quality factors for several configurations. The computed results are found to be in excellent agreement with those observed in the literature. The numerical results obtained show that the bandwidth increases with the increase in the thickness of the suspended or composite substrates, especially for low permittivity of the second layer. Also, it is demonstrated that the resonant frequencies of the circular microstrip patch on suspended and composite substrates can be adjusted to obtain the maximum operating frequency of the antenna. Finally, the effect of the presence of the second layer under the circular patch on the radiation patterns is also investigated.

FULL-WAVE ANALYSIS OF ANISOTROPIC CIRCULAR MICROSTRIP ANTENNA WITH AIR GAP LAYER

In this paper, the efiect of both uniaxial anisotropy in the substrate and air gap layer on the resonant frequency and bandwidth of circular microstrip patch are investigated. The problem is rigorously formulated based on the spectral domain technic in conjunction with Galerkin approach for computing the resonant frequency, half-power bandwidth, and radiation fleld of a tunable circular patch antenna which is printed on isotropic or uniaxial anisotropic substrate. The TM set of modes issued from the magnetic wall cavity model theory are used to expand the unknown currents on the patch. Resonant frequency shift due to uniaxial anisotropy is flrstly investigated for difierent anisotropy ratio values of substrate. Then, the efiect of inclusion of air gap layer inserted between anisotropic substrate and ground plane on the resonance characteristics is also investigated. The results obtained from this approach are in very good agreement with the experimental results available in the literature.

Study of High Tc Superconducting Microstrip Antenna

Resonant characteristics of microstrip antennas with superconducting fllms is pre- sented. The analysis is based on a full electromagnetic wave model with London's equations and the two-∞uid model. It is shown that the full-wave analysis presented here gives numerical results which are in excellent agreement with the measured data available in the literature. Re- sults showing the efiect of the temperature on the resonant frequency and half-power bandwidth of superconducting microstrip antenna are given. Variations of the resonant frequency with the high Tc superconducting fllm thickness are also presented. Superconducting passive microwave devices such as antennas, fllters, transmission lines, and phase shifters have shown signiflcant superiority over corresponding devices fabricated with normal con- ductors such as gold, silver, or copper due to the advantages of superconductors (1). Advantages of using high Tc superconducting materials at high frequencies include (2): 1) very small losses, which means reduction of attenuation and noise level; 2) very small dispersion up to frequencies of several tens of GHz; 3) smaller devises due to the lower losses, which leads to larger integration density; and 4) the propagation time can be greatly reduced because of the smaller size and the shorter interconnects. In the literature, the studies concerning the resonance characteristics of microstrip antennas using perfectly conducting patches are abundant. However, few works have been done for the case of microstrip antennas using superconducting patches. The determination of the resonant frequencies of superconducting microstrip patch antennas was initially carried out by means of the magnetic wall cavity model (3). Later on, these resonant frequencies were obtained by using the rigorous full-wave analysis (4). To validate the theoretical analysis, the authors in (4) have compared their numerical results with the experimental data of Richard etal. (3). This comparison has not been done in a convenient way for two reasons: the variation of the permittivity of the lanthanum aluminate substrate with the variation of the temperature, as indicated by the experiment of Richard etal. (3), has not been take into account by Silva etal. (4) and the efiect of varying the temperature on the resonant frequency is insigniflcant. In this paper, we present a theoretical and numerical analysis of the resonant frequencies of high Tc superconducting rectangular microstrip antennas which yields excellent agreement with the mea- sured data of Richard etal. (3). To include the efiect of the superconductivity of the microstrip patch in the full-wave analysis, a surface complex impedance is considered. This impedance is de- termined by using London's equation and the two-∞uid model of Gorter and Casimir (2). Numerical results for the efiect of the temperature on the resonant frequency and half-power bandwidth of superconducting microstrip antenna are given. Finally, the in∞uence of the thickness of the high Tc superconducting fllm on the resonant frequency is also presented. 2. THEORY

Full-Wave Spectral Analysis and Design of Annular Patch Antenna With Electromagnetically Coupled Microstrip Feed Line

This paper presents a full-wave analysis, and the ensuing design considerations, of the annular patch antenna fed by an electromagnetically coupled microstrip line. The numerical analysis employs the spectral domain version of the integral equation, with the method of moments formulation; the basis functions on the ring patch are the eigenmodes of the corresponding magnetic wall cavity, and subsectional (rooftop) functions are employed on the access line. Both TM and TE modes are used, along with more-efficient "collective" solenoidal modes; mode sorting criteria are given to ensure uniform convergence. Efficient schemes are presented for the calculation of the spectral-domain reaction integrals, along with criteria to avoid calculation of negligible mode-to-mode couplings, based on the spectral analysis of the matrix condition number. Very good agreement is shown with measured data, and design considerations are given for matching the radiator.

Numerical analysis of rectangular microstrip patch over ground plane with rectangular aperture

In this paper, a rigorous full-wave analysis of rectangular microstrip patches over ground planes with rectangular apertures in substrates containing isotropic and anisotropic materials is presented. The dyadic Green's functions of the problem are efficiently determined in the vector Fourier transform domain. The integral equations for the unknown patch current and aperture field are solved numerically by applying the Galerkin method of moments. The TM set of modes issued from the magnetic wall cavity model are used to expand the unknown current on the patch. Also, the same basis functions are used for approximating the aperture field in accordance with the concept of complementary electromagnetic structures. The validity of the solution is tested by comparison of the computed results with experimental data. Numerical results show that changes in aperture length can drastically shift the resonant frequency. The aperture width, on the other hand, can be used for a fine adjustment of the operating frequency. Other results also indicate that dielectric anisotropy effect is especially significant when the size of the aperture is similar to that of the patch. Copyright © 2004 John Wiley & Sons, Ltd.

On the use of cavity modes as basis functions in the full wave analysis of printed antennas

Magnetic wall cavity (MWC) modes are often employed as basis functions in the method of moments (MoM) full wave analysis of printed antennas, especially in its spectral domain version, where the use of entire domain basis functions is particularly convenient, but in some cases the TE (solenoidal) modes are not included. Here we investigate on the effect of this exclusion, explaining the nature of the TE-TM coupling, presenting criteria to determine the necessary number of modes, and giving numerical results for annular patches, especially relevant in this context.

Application of numerical regularization options to the integral-equation analysis of printed antennas

In this letter, a novel numerical technique is applied to the analysis of printed antennas. The technique transforms the first-kind electric-field integral equation (EFIE) into a regularized second-kind equation, via extraction of two singular frequency-independent operators and their numerical inversion. Two options are presented in which the inversion is based on the eigenfunctions of these singular operators, that appear to be a generalization of the TM and TE modes of a magnetic-wall cavity, coupled by the edge singularities. The example of application shows favorable convergence properties.

Input impedance of spherical microstrip antenna

The input impedance of a spherical microstrip antenna excited by a coaxial probe is analysed. Both the TM11 mode of spherical circular microstrip antenna and the TM12 mode of spherical annular microstrip antenna are considered. Galerkin's procedure is used to solve the surface current on the patch. The effects of the dielectric thickness and the size of the sphere on the input impedance are studied. Results are compared with antennas on planar surface and with perfect magnetic wall cavity model.

Resonant frequency of a triangular microstrip antenna

AbstractA new very simple effective side length and effective relative dielectric constant expressions are presented for a triangular microstrip antenna. The theoretical resonant‐frequency results obtained from the magnetic wall cavity model with this new effective side length and effective relative dielectric constant expressions are in very good agreement with experimental results available in the literature. © 1993 John Wiley & Sons, Inc.