摘要:

The purpose of the review is to provide an up-to-date coverage of the field of microstrips, the general appearance of printed circuits and antennas, the techniques utilised to fabricate and connect them, the materials most currently used and, finally, the powerful computer software available to analyse and design, and actually to prepare and to cut the masks required to manufacture circuits and antennas. The review is completed by an extended bibliography.

DOI:10.1049/ip-h-2.1988.0033

出版商:IEE    

年代:1988

数据来源: IET

摘要:

The radiation characteristics of conical horns loaded with dielectric cones are investigated. The horn radiates low crosspolarisation over a wide band of frequencies with cones made of foam or solid dielectrics. They make high performance feeds for reflector antennas. A modal-matching technique is used to investigate the behaviour of the higher order modes excited along the horn that influence the radiated cross-polarisation. A parametric study is described to assess the influence of the aperture and cone diameters, the flare angle, and the permittivity of the dielectric.

DOI:10.1049/ip-h-2.1988.0034

出版商:IEE    

年代:1988

数据来源: IET

摘要:

Using a dielectric resonator in microwave filter applications, several types of excitations can be considered. An HEM110–mode filter, used in satellite applications, utilises coaxial probes for the coupling of dielectric resonators with the external ports. In the paper the authors present the determination of the input impedance and of the coupling parameters between a probe and a dielectric resonator, when the pin is placed in the radial plane of a structure containing a cylindrical dielectric resonator.

DOI:10.1049/ip-h-2.1988.0035

出版商:IEE    

年代:1988

数据来源: IET

摘要:

A new method of pattern synthesis for antenna arrays, based on the expansions of eigensources and eigenpatterns with an iterative modification of phase pattern, is presented which has been applied successfully to the array of either isotropic or anisotropic elements. Several numerical examples are given which illustrate the advantages of this method.

DOI:10.1049/ip-h-2.1988.0036

出版商:IEE    

年代:1988

数据来源: IET

摘要:

Linear models for high-frequency transistors (bipolar and MESFET) at different biasing conditions are described. The model for a bipolar (MESFET) transistor shows good agreement between the measured and simulatedY(z) parameters. A discrete high frequency transistor is represented as a combination of two transistors and the bias dependence of the parameters of both intrinsic and extrinsic transistors are determined. A fully-automated equivalent-circuit parameter extraction program to fit the measured two-port MESFET data optimally up to 18 GHz is developed.

DOI:10.1049/ip-h-2.1988.0037

出版商:IEE    

年代:1988

数据来源: IET

摘要:

The use of coplanar corporate feeds for microstrip patch arrays leads to constructional simplicity, but also to performance degradations due to feed radiation, in addition to limitations due to feed resistive loss, surface waves, mutual coupling and tolerances. These effects are quantified, and this allows specification of array performance limitations in addition to the recommendation of the use of smooth feed discontinuities, high line impedance, and thin substrates. Improvements due to the use of alternate feed geometries, such as sequentially rotated feeding and subarraying, are also quantified and are shown to be substantial.

DOI:10.1049/ip-h-2.1988.0038

出版商:IEE    

年代:1988

数据来源: IET

摘要:

The analysis and optimal design of a microstrip sensor for measuring the water content of rubber latex is described. The microstrip structure consists of three layers: substrate, protective layer and semi-infinite layer of wet medium. A functional relationship has been developed between the attenuation and the water content of the latex, and close agreement has been found between the computed and experimental results. A computer program has also been developed which optimises the sensitivity for a given water content.

DOI:10.1049/ip-h-2.1988.0039

出版商:IEE    

年代:1988

数据来源: IET

摘要:

The oscillation frequency of IMPATT cap oscillators is close to the frequency of the resonator formed by the cap and the diode capsule. In the design of the oscillator or interpretation of its behaviour, knowledge of the cap resonance frequencies and of their dependance upon the geometry and characteristics of the diode is desirable. Assuming radial wave propagation beneath the cap with either shunt or ‘cross’ connection of the diode, good agreement between the measured and estimated resonance frequencies was obtained. Including the cap representative circuit in that for the oscillator, the tuning characteristics were derived assuming a capacitive reactance for the diode. The effect of post inductance was to reduce the potential octave tuning range of Q-band oscillators to a few GHz for the practical range of cap diameters. The study of cap, post, and waveguide coupling effects leading to a more exact representation and the introduction of an active model for the diode, would extend understanding of the frequency range and power capability of the oscillator.

DOI:10.1049/ip-h-2.1988.0040

出版商:IEE    

年代:1988

数据来源: IET

摘要:

The powers transmitted and lost at an abrupt discontinuity in planar guides are calculated numerically using the beam propagation method (BPM) for the TE–modes. Discontinuities include changes in core thickness and refractive index. Symmetric and asymmetric waveguides are considered. Comparison of results with those obtained by other techniques shows a general agreement.

DOI:10.1049/ip-h-2.1988.0041

出版商:IEE    

年代:1988

数据来源: IET

摘要:

Using Wheeler's formula and following Cohn's procedure, theoretical expressions are derived for the conductor loss in square and rectangular coaxial lines. An example is given for a square coaxial line, and good agreement is obtained between these expressions.

DOI:10.1049/ip-h-2.1988.0042

出版商:IEE    

年代:1988

数据来源: IET