An aperture coupled microstrip antenna with a proximity feed on a perpendicular substrate

A new feeding configuration for microstrip antennas is described, where separate substrates are used for the radiating patch element and the microstrip feedline. The substrates are joined perpendicular to each other, and the patch is excited through an aperture in the antenna substrate ground plane by proximity coupling to the microstrip feedline, This design thus has a number of advantages over other feeding configurations, particularly when used in an integrated phased array application. These features, as well as the measured results from two experimental models, are described.     

Circularly polarised aperture coupled microstrip antenna

The orthogonal mode of an aperture coupled rectangular microstrip antenna can be coupled to the aperture-excited mode with coplanar microstrip lines to provide a compact circularly polarised element with a single aperture feed. An equivalent circuit model was developed for the analysis and design of this element, and a working version was used to demonstrate the concept. The features of this antenna are compared with several other circularly polarised microstrip antennas     

Wideband aperture coupled stacked patch antenna using thicksubstrates

An aperture coupled stacked patch microstrip antenna is presented which is capable of operating over a bandwidth in excess of 50%. Measured and predicted impedance behaviour and gain over the band are given. Other important factors such as surface wave efficiency and back radiation levels are presented     

Magnetic tuning of a microstrip antenna on a ferrite substrate

The operating frequency of a microstrip antenna on a ferrite substrate can be tuned by varying the DC magnetic bias field applied to the ferrite. The letter reports experimental work where a 40% tuning range has been obtained, with usable patterns and return loss over this band     

Scanning characteristics of infinite arrays of printed antennasubarrays

The analysis and scanning characteristics of several different types of infinite arrays composed of subarrayed printed dipole and microstrip patch elements are presented. The analysis is based on full-wave moment method theory, and includes mutual coupling between elements in the subarray as well as between subarrays. The effect of subarraying on scan blindness is demonstrated for arrays using two-element subarrays of printed dipoles and microstrip patches. Results are also given for the amount of power radiated in grating lobes. The effect of a subarray composed of one driven element and one parasitic element, and the use of a four-element synchronous subarray of microstrip patches to generate circular polarization are also considered. Data are given for impedance mismatch, power radiated into grating lobes, and the axial ratio; both square and rectangular patches area considered. Results are also shown for an infinite array of seven-element hexagonal subarrays of printed dipoles, and it is found that the large spacing between subarrays leads to a limited scan range     

Phased arrays of probe-fed stacked microstrip patches

This paper presents calculated and measured results for infinite phased arrays of probe-fed stacked rectangular and circular microstrip patches. A numerical model is described that is based on a rigorous Green's function/Galerkin solution. In this solution, the connection of one or more vertical probe feeds to each patch is accurately modeled using a special attachment mode basis function, which is derived from the corresponding cavity model solution. Numerical results for both linearly and circularly polarized arrays are obtained. Measured results from a waveguide simulator are also presented and used to validate the numerical model     

Radiation and scattering from infinite periodic printed antennaswith inhomogeneous media

The hybrid method of moments (MoM)/Green's function method technique is applied to infinite periodic printed antenna arrays containing dielectric inhomogeneities. The solution uses an integral equation for an infinite periodic printed array on or over a homogeneous dielectric substrate, coupled with equivalent volume polarization currents for dielectric inhomogeneities on top of the homogeneous substrate. Volume pulse-basis functions were used to expand the volume polarization currents. A hybrid MoM/Green's function method solution was then obtained through the matrix form of the problem. The two-dimensional (2-D) solution of plane wave scattering from a grounded dielectric slab was used to validate the reaction impedance of the dielectric inhomogeneity. Several infinite periodic printed dipole arrays with dielectric supports and overlays were studied with this solution and good agreement was observed between the hybrid MoM/Green's function method and waveguide simulator experiments     

Comparison of three methods for the measurement of printed antennaefficiency

Three methods for the measurement of antenna efficiency are evaluated: (1) the Wheeler cap method, (2) the radiometric method, and (3) the directivity/gain method. Each of these methods was used to measure the efficiency of four different printed antennas (three microstrip patches with various feeds, and an eight-element series-fed microstrip array). These methods and the experimental results which were obtained are discussed     

Increasing the bandwidth of a microstrip antenna by proximity coupling

The letter presents experimental results for a proximity-coupled microstrip patch antenna capable of 13% bandwidth. The impedance match (VSWR ? 2), copolarised radiation patterns and crosspolarised radiation were measured over this bandwidth to confirm operation. The construction is quite simple, consisting of a microstrip feedline on a substrate proximity-coupled to a rectangular microstrip patch on a covering superstrate; a small open-circuit tuning stub is connected in shunt with the feed line.