Microstrip Antenna For Applications Research Articles

Numerische Analyse aperturgekoppelter Streifenleitungsantennen mit MAFIA

Microstrip and planar antennas are widely used in the field of mobile communication and radar applications. For an accurate calculation of the antenna properties efficient numerical techniques are used. These are very valuable design tools. An aperture coupled microstrip antenna for applications in the X-Band (9.6 GHz) is simulated by means of MAFIA using the FIT-Algorithm (Finite Integration Technique). The results are compared with a simulation based on a combination of the integral equation method and the method of moments. The simulation results show very good agreement both with measurements of the reflection coefficient and the farfield of the antenna, and with results from the combined method of integral equation and method of moments.

Superconducting microstrip antennas: an experimental comparison of two feeding methods

The recent discovery of high-temperature superconductors (HTSs) has generated a substantial amount of interest in microstrip antenna applications. However, the high permittivity of substrates compatible with HTS causes difficulty in feeding such antennas because of the high patch edge impedance. Two methods for feeding HTS microstrip antennas at K- and Ka-band are examined. Superconducting microstrip antennas that are directly coupled and gas-coupled to a microstrip transmission line have been designed and fabricated on lanthanum aluminate substrates using Y-Ba-Cu-O superconducting thin films. Measurements from these antennas, including input impedance, bandwidth, efficiency, and patterns, are presented and compared with published models. The measured results demonstrate that usable antennas can be constructed using either of these architectures, although the antennas suffer from narrow bandwidths. In each case, the HTS antenna shows a substantial improvement over an identical antenna made with normal metals.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An SEM analysis of the voltage induced upon a printed strip antenna by a transient plane wave

The singularity expansion method (SEM) is applied to study the interaction of a transient electromagnetic plane wave with a printed strip antenna. In SEM, the time-domain response of the element is separated into excitation-independent natural resonances and modes, which have considerable physical significance, and closed-form coupling terms which can be rapidly evaluated as the geometric or temporal properties of the source change. The SEM is demonstrated as applied to the transient microstrip problem, and the effect of varying the properties of the printed circuit substrate over a range of values typically found in microstrip antenna applications is studied. The transient response due to a step and Gaussian excitation is studied. It is found that the level of transient signal induced on a printed element increases with increasing substrate permittivity. The shape of the induced voltage or current waveform is highly dependent on the geometric and temporal properties of the source for elements printed on relatively thin substrates, while, for elements printed on thicker substrates, the shape of the induced waveform is much less sensitive to the form of the excitation, and resembles the oscillation of the fundamental resonance of the antenna. >

A broad-band annular-ring microstrip antenna

A heuristic discussion of the radiation properties of the transverse magnetic (TM 11 ) and (TM 12 ) modes of the annular-ring microstrip antenna is presented, indicating the possibility of the TM 12 mode as a superior microstrip antenna. Rigorous analyses of the resonant frequency characteristics of the antenna are then performed with the matched asymptotic expansions technique and the perturbation approach. The analyses show that the TM 12 mode is decidedly the best mode for microstrip antenna applications while the TM 11 mode, having a high Q -factor, is best reserved for resonator applications. The analyses include the study of the resonant frequencies, bandwidths, and radiation pattern of the antenna. The matched asymptotic expansions technique and the perturbation approach are also shown to agree excellently with each other within their domain of validity.

High-frequency behaviour of microstrip open-circuit terminations

The extensive use of open-circuit microstrip terminations as tuning stubs and, more recently, as antenna elements, demands design data on the frequency-dependent characteristics of the termination. A variational solution for the end admittance is formulated using discrete and continuous mode distributions to represent the radiation, evanescent and substrate surface-wave fields. Computed results for a variety of line widths on polyguide and alumina substrates are compared with available experimental and theoretical data. It is established that useful admittance curves can be readily calculated using a simple trial aperture field, and the functional form of the curves is independently predicted by a Hilbert-transform relationship. The frequency-dependent end admittance reveals the lower frequency range over which a given substrate is suitable for unshielded high-Q circuit applications and the higher-frequency region for microstrip antenna applications. The generation of substrate surface waves increases with frequency, and sets an upper frequency limit for microstrip antenna applications. Other practical issues of interest such as radiation patterns, intercircuit coupling and resonator losses are briefly considered and the usefulness of this approximate analysis, which represents the most complete treatment to date, is evident.