Analysis and design of aperture-coupled microstrip patch antennasand arrays fed by dielectric image line

This paper presents the analysis and design of aperture-coupled microstrip patch antennas and arrays fed by an dielectric image line. A theory based on the cavity model of the microstrip patch antenna and the change in the modal voltage of the image line at the aperture was developed to analyze the single element aperture-coupled microstrip patch antenna. The theory developed was combined with the array theory to design linear traveling wave arrays at X-band and Ka-band frequencies. The required taper in the excitations of the individual patches of the array was achieved by varying the aperture dimensions. Experiments show very good results for the antennas and the arrays     

Slotline ring resonator test method for high-Tcsuperconducting films

A novel method of testing high-T_c superconducting (HTS) films by means of a slotline ring-like resonator is presented. This method does not require any metallic contact with the HTS films and ensures that the tests have quick turnaround times. Small samples can be tested very easily. The resonator circuit used has been studied analytically using Sonnet Inc.'s em software. The parameters of the HTS films are obtained by fitting the theoretical results to the experimental ones. YBa₂Cu₃O_7-δ films on LaAlO₃ have been tested and the theoretical and experimental results are presented and compared. The results match very well. This method is useful for quick screening HTS films since no patterning of the film is required     

Design of aperture coupled microstrip antenna array fed bydielectric image line

A novel design for a linear array of microstrip antennas, aperture coupled to a dielectric image line has been developed. The design is based on a simplified theory to determine the impedances of the antennas at their apertures, and in turn, the coupling to each antenna from the image line. The theory developed is verified using an eight-element linear array and the experiment results are very good     

Aperture coupled beam steering microstrip antenna array fed bydielectric image line

Five- and eight-element patch antenna arrays linearly fed by dielectric image lines have been developed with good E-plane and H-plane patterns. The measured results and the calculated beam steering angles agree very well. Crosspolarisations are 20 dB and side lobes are 15 dB below the main lobe     

Syntheses and Characterization of 1,4‐Phenylenebisphosphonates,A[HO3PC6H4PO3H2] (A = Li,K, Rb,Cs, Tl,Ag and NH4) and Crystal Structure of 1,4‐Phenylenebisphosphonic Acid

Seven 1,4‐phenylenebisphosphonates of monovalent ions, A(HO₃PC₆H₄PO₃H₂) (A = Li, K, Rb, Cs, Tl, Ag and NH₄), were synthesized and characterized by single‐crystal X‐ray diffraction, spectroscopic and thermal methods. These compounds and the reported sodium analogue have four structure types. The sodium compound, one‐dimensional lithium compound and pillared‐layered cesium compounds have different structure types, whereas the potassium, rubidium, thallium, ammonium and silver compounds have a pillared ladder‐like structure. They undergo initial thermal decomposition in the range of 120–270 °C. Moreover, the single crystal X‐ray structure of 1,4‐phenylenebisphosphonic acid was determined.