Showing papers on "Microstrip antenna published in 1982"

Antenna Theory: Analysis and Design

Abstract: The most-up-to-date resource available on antenna theory and design Expanded coverage of design procedures and equations makes meeting ABET design requirements easy and prepares readers for authentic situations in industry New coverage of microstrip antennas exposes readers to information vital to a wide variety of practical applicationsComputer programs at end of each chapter and the accompanying disk assist in problem solving, design projects and data plotting-- Includes updated material on moment methods, radar cross section, mutual impedances, aperture and horn antennas, and antenna measurements-- Outstanding 3-dimensional illustrations help readers visualize the entire antenna radiation pattern

Input impedance and mutual coupling of rectangular microstrip antennas

Abstract: A moment method solution to the problem of input impedance and mutual coupling of rectangular microstrip antenna elements is presented. The formulation uses the grounded dielectric slab Green's function to account rigorously for the presence of the substrate and surface waves. Both entire basis (EB) and piecewise sinosoidal (PWS) expansion modes are used, and their relative advantages are noted. Calculations of input impedance and mutual coupling are compared with measured data and other calculatious.

Design of microstrip antennas covered with a dielectric layer

Abstract: The design of a microstrip antenna covered with a dielectric layer is presented. Due to loading, the resonant frequency of the antenna changes. The absolute value of the change increases with the operating frequency, the relative permittivity (except plasma), and the thickness of the dielectric layer. This change may cause degradation in performance due to the inherent narrow bandwidth of microstrip antennas if the effect of loading is not considered in the design. The curves presented here may be used to design microstrip antennas that may be subjected to icing or a plasma environment or coated with protective layers. Numerical and experimental results for the fractional change in the resonant frequency are round to be in good agreement.

A broad-band annular-ring microstrip antenna

Abstract: 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.

A frequency agile microstrip antenna

Abstract: This paper describes a novel technique for increasing the operational frequency bandwidth of microstrip patch antennas, by using varactor diodes at the radiating edges of the structure. Theoretical and experimental results confirm that bandwidths of the order of 30% are achievable compared to 1-2% for the unloaded patch radiator.

Vector Hankel transform analysis of annular-ring microstrip antenna

Abstract: A rigorous analysis of the resonant frequency characteristics of an annular-ring conductor printed on a dielectric substrate backed by a ground plane is presented. The problem is cast into a set of vector dual integral equations by using vector Hankel transform (VHT). Galerkin's method is then applied to compute the resonant frequencies of both transverse magnetic modes (TM 11 and TM 12 ) of the microstrip antenna. The real part of the resonant frequency shift of the TM 11 mode increases with increasing dielectric thickness in contrast to the TM 12 mode. While the TM 11 mode has a high Q , it is a poor radiating mode; the TM 12 mode is more suitable for antenna applications. For a probe excitation the input impedance is obtained using single mode approximation for both the TM 11 and TM 12 modes. It is shown that the TM 12 mode of the annular ring has a greater bandwidth than the TM 11 mode.

Input impedance of microstrip antennas

Abstract: Using Richmond's reaction integral equation, an expression is derived for the input impedance of microstrip patch antennas excited by either a microstrip line or a coaxial probe. The effects of the finite substrate thickness, a dielectric protective cover, and associated surface waves are properly included by the use of the exact dyadic Green's function. Using the present formulation the input impedance of a rectangular microstrip antenna is determined and compared with experimental and earlier calculated results.

Integral equation formulation of microstrip antennas

Abstract: The problem of a microstrip antenna covered by a dielectric is formulated in terms of coupled integro-differential equations with the current distribution on the microstrip patch as an unknown variable. Galerkin's method is used to solve for the unknown patch current. Using the present formulation the resonant frequency and bandwidth of a rectangular microstrip antenna are determined and compared with experimental results.

The synthesis of shaped patterns with series-fed microstrip patch arrays

Abstract: A method of designing series-fed microstrip patch arrays to produce a shaped pattern is described. The technique is based on a circuit representation of the patches in the array environment with experimentally determined parameters. The positions and widths of the patches are derived from the amplitudes and phases of the elements of a uniform array, which produces the desired pattern and which has the same extent as the patch array. For the array to have high efficiency, the amplitude distribution mast not be strongly peaked. An algorithm for obtaining an approximation to the desired far-field amplitude distribution while retaining control over the amplitude of excitatian is presented. Very close agreement has been obtained between calculated and measured performance of such arrays.

The thin-substrate approximation for reflection from the end of a slab-loaded parallel-plate waveguide with application to microstrip patch antennas

Abstract: Integrals arising in the Wiener-Hopf solution for wide microstrip antennas are approximated in closed form for the case of an electrically thin substrate. The resulting expressions are used to obtain simple, closed-form expressions for resonant frequency and unloaded radiation Q for rectangular microstrip patch antennas which are valid when commonly used quasi-static formulas no longer hold. Numerical comparisons show significant shifts in resonant frequencies as compared with existing theories.

Electronically tunable microstrip antenna

Abstract: A microstrip antenna with a linearly polarized radiating patch is varied in resonant frequency by an electronic tuning technique. A dc bias voltage is combined with the excitation signal to regulate the capacitance of a varactor diode mounted in the antenna structure. In one embodiment the varactor is in shunt with a half wave open circuited radiator and adds electrical length to the antenna, while in another embodiment the varactor is in series with a shorted quarter wave radiator and subtracts electrical length therefrom.

Mutual coupling between microstrip antennas

Abstract: A theoretical study of mutual coupling between microstrip antennas is presented. The cavity method is used, and from the equivalence theorem application the problem is reduced to interaction of two magnetic loops. The mutual impedance is then calculated from the reaction theorem. Theoretical results and measurements are in good agreement.

Characteristics of annular-ring microstrip antenna

Abstract: The characteristics of an annular-ring microstrip antenna operating in TM11 and TM12 modes are determined experimentally. Our results confirm the main conclusions of a theoretical study published recently by Ali, Chew and Kong and show that: (a) the bandwidth of the TM11 mode is very small while that of the TM12 mode is relatively large, and (b) the lauching efficiency of the TM12 mode is highly sensitive to the feed position while that of the TM11 mode is virtually independent of the feed position.

Microstrip-Franklin Antenna

Abstract: Phasing stubs are employed to achieve a cophase current distribution in microstrip rectangular patch arrays. This technique, originally proposed for resonant long wire antennas by Franklin, avoids spurious radiation from half-wavelength connecting transmission lines as used in conventional patch antenna arrays. A slot-radiator model is derived to describe the basic radiation mechanism of the resultant new type of antenna and experimental results for the slot radiation resistance are given. The design of a 13-element resonant array for 12 GHz is presented together with measured radiation patterns.

Microstrip notch antenna

Abstract: A broadband radiating element design is disclosed which provides a smooth, continuous transition from a microstrip feed configuration to a flared notch antenna for transmitting or receiving radio frequency signals.

Mutual coupling between microstrip patch antennas

Abstract: A theoretical approach to the mutual coupling phenomenon between microstrip patch antennas of arbitrary geometry and alignment is presented. The theory employs an equivalent magnetic wall model for each single radiator, a series expansion in resonant modes in connection with a reaction concept treatment of antenna interaction. Good agreement of theoretical and experimental data is observed in a wide frequency range for various element spacings.

Rectangular microstrip antenna on a ferrite substrate

Abstract: The bandwidth and radiation characteristics of a simple quarter wave microstrip antenna on a typical ferrite substrate are measured and compared with the theoretical results in the lower range of ultrahigh frequency (UHF). A method has also been discussed for impedance matching of the antenna to the feed line.

Blade antenna with shaped dielectric

Abstract: A Tee slot blade antenna for aircraft and other high speed vehicles has a pair of dielectric sections, one section extending longitudinally along the blade and the other extending transversely from an intermediate location along the longitudinal section. The resonant frequency of the antenna is determined by the length of each section and the position of the transverse section along the longitudinal one, while the characteristic impedance is a function of the width of each section. The Tee slot antenna is capable of operating over a wide bandwidth on a smaller blade than prior single slot antennas. A Tee slot antenna designed for one frequency range can be combined with either a single slot antenna or another Tee slot antenna designed for another frequency range on the same antenna blade, without impairing the bandwidth of either antenna.

E-plane performance trade-offs in two-dimensional microstrip-patch element phased arrays

Abstract: A systematic analysis of probe-fed microstrip-patch phased arrays is discussed based on an infinite array model. E -plane scan and frequency parametric study of two-dimensional strip arrays show characteristic scan-bandwidth trade-offs.

Study on ellipticity properties of single-feed-type circularly polarised microstrip antennas

Abstract: The letter presents the basic method for the design of single-feed-type circularly polarised microstrip antennas (SCPA). An SCPA designed to operate under condition of circular polarisation (OCCP) proved to produce an axial ratio below 0.5 dB at the boresight. Moreover, the measured and calculated axial ratios for SCPA agreed well within the effective range. These results indicate the use of the design method reported in the letter for construction of SCPA with excellent directivity.

Broadband microstrip antennas with varactor diodes

Abstract: A microstrip antenna is disclosed consisting of a flat metallic patch spaced from the ground plane. To increase the bandwidth of the antenna a pair of varactor diodes are provided positioned at opposite sides of the patch and connected between it and the ground plane.

Slotted antenna array excited by a coplanar waveguide

Abstract: The letter gives a new concept of exciting slotted antenna arrays. There both the slots and the feeder are etched on the same side of the printed circuit board. A channel is cut perpendicular to the slots and a coplanar waveguide for exciting the slots is inserted into the channel. The concept has been experimentally verified on a model.

Improved formulas for input impedance of coax-fed microstrip patch antennas

Abstract: The input impedances of rectangular and circular antennas have been improved by more accurate expressions for the input reactances and radiation conductances. The theory includes the effects of extended antenna patches due to fringe fields at the edge. Surface toughness of the dielectric substrate has also been accounted for. The measured and calculated curves for input impedances agree well.

Broadband circular disc microstrip antenna

Abstract: A technique for broadening the bandwidth of the circular disc microstrip radiating element is described. Theory based on a simple circuit model is introduced and comparison with experimental work is shown. From this model, a matching circuit is devised, the resulting element giving a bandwidth of 35% (to a VSWR of 1.5) near 8 GHz. This makes the circular disc element suitable for a wide range of radar and communications antenna systems.

Microstrip antenna with protective casing

Abstract: A microstrip antenna is presented in which the circuit pattern is on the inner side of a glass plate and is spaced from the ground plane by an air dielectric. The outer side of the glass plate serves as a protective cover for the circuit pattern and the ground plane.

Apparatus and method for coupling r.f. energy through a mechanically rotatable joint

Abstract: First and second annular r.f. radiating structures are mounted for concentric relative rotational motion with their r.f. radiation patterns directed toward one another. The annular r.f. radiating structures may be realized, for example, by cylindrically conformed microstrip antenna radiators which define tuned resonant cavities feeding one or more radiation apertures defined between an edge of a microstrip radiator "patch" and an underlying electrical reference or ground surface. The microstrip radiator "patch" may be either continuous in its circumferential dimensions or it may have occasional circumferential discontinuities formed by axially directed gaps therein. If the total circumferential dimension is greater than one wavelength at the intended operating frequency, then a corporate structured feedline provides plural spaced-apart feedpoints about the circumference so as to achieve a substantially uniform distribution of r.f. field amplitudes and phases about the circumference.

Far field radiated by rectangular patch microstrip antenna

Abstract: Using the volume equivalence theorem, we introduce electric and polarisation current distributions for a rectangular patch microstrip antenna. These distributions are known from transmission-line-model analysis. Literal formulas are given especially to express the E-plane radiation pattern and the worst-case crosspolarisation level. Theoretical results are in good agreement with experiments.