This paper describes a method for designing backfeed-type one-point fed circularly polarized antennas. These antennas are fed at one point from the back side of the substrate and have degeneracy-resolving segments. Characteristics of the rectangular microstrip antennas with degeneracy-resolving segments are obtained by means of a variational method. The equivalent circuit at and near the resonance with perturbations is obtained and the condition for circularly polarized antennas is found from both theoretical and experimental viewpoints. Configurations and radiation characteristics of these antennas are discussed and it is shown that these antennas can be used as array elements.

A design method of circularly polarized rectangular microstrip antenna by one‐point feed

Sensors fabricated on a thermally insulating thin inorganic membrane are described together with their applications. The device power consumption, level of response, response times and practical limitations are compared with theory. The use of the devices as sensors for pressure, flow rate and gas type is demonstrated. Pressures can be measured from about 10 −3 mbar to a few atmospheres; flow rates of at least 1 m s −1 can be determined and a number of different gases can be identified. The sensor is normally operated in the temperature range 125–250 °C while consuming typically less than 10 mW of power with sensor response times of less than one second. The device is made using an inexpensive fabrication technique that is compatible with CMOS processing.

Applications of thermal silicon sensors on membranes

Silicon-on-insulator by oxygen implantation: an advanced technology

The remaining defects in separation by implanted oxygen (SIMOX) structures are shown to be dislocations, stacking faults and buried oxide discontinuities. The defect categories are reviewed and their density in standard material is given. Results of an enhanced chemical etching characterization technique are presented. The dependence of defect density on process parameters is given and the mechanisms of defect formation discussed. An experiment that allows “defect engineering” is also reported.

Defects in SIMOX structures: some process dependence

Defects in SIMOX structures: causes and solutions

A method for altering the resonant length of a square micro-strip antenna is described. The relevant analysis and computations have been carried out to propose a possibility of realising a microstrip antenna having comparatively smaller dimensions and larger bandwidth.

G.C. Das

Papers

Resonant length of a linearly polarised microstrip radiator