摘要:

Ferrite-latching phase shifters in a generalised waveguide geometry (grooved rectangular guide with lateral ridges) are analysed using a combination of mode-matching and perturbation techniques. By this method, the double transverse inhomogeneities of the waveguide configuration and of the toroid corner magnetisation are both considered exactly, leading to accurate predictions of differential phase shift and of cutoff frequencies of higher-order modes.

DOI:10.1049/ip-h-2.1986.0027

出版商:IEE    

年代:1986

数据来源: IET

摘要:

Improved stopband attenuation ofE-plane filters is achieved by replacing merely a few of the conventional single insert coupling elements by triplets or quintuplets of metal inserts. The method of field expansion into suitable eigenmodes used considers the effects of finite insert thickness and the mutual higher order mode interaction of all inserts. Calculated stopband attenuations of more than 50 dB up to about 30 GHz, or 60 GHz respectively, have been attained, although the passbands of the corresponding filter examples are chosen to operate at the upper waveguide band limit of the mount (at 18 GHz for Ku-band and at 40 GHz for Ka-band respectively). The results demonstrate that high stopband conditions can be satisfied by designs with only a modified number of multiple inserts. This helps to maintain the low-loss and low-cost qualities ofE-plane filters and also provides for improved stopband demands. The thickness of all inserts oft= 190 µm makes possible accurate metal-etching fabrication.

DOI:10.1049/ip-h-2.1986.0028

出版商:IEE    

年代:1986

数据来源: IET

摘要:

Noise and transfer properties of frequency multipliers with step-recovery diodes and depletion-layer varactors are investigated both theoretically and experimentally. Parameters are the multiplication factor the number of diodes drive level and detuning of the input frequency, the bias conditions and the terminations at the harmonics. Distortions of angle-modulated signals mainly originate in AM-PM-conversion whereas the intrinsic noise plays only a subordinate role. Fixed bias and detuning either the input or the output circuit are remedy against this source of distortion. The bias modulation sensitivity is also investigated snowing that the bias supply voltage must be carefully stabilised in order to reduce the PM output noise.

DOI:10.1049/ip-h-2.1986.0031

出版商:IEE    

年代:1986

数据来源: IET

摘要:

Images of biological objects can be obtained by exploration with microwaves. Reconstitution of the image takes place by distribution in phase and in amplitude of the diffracted field on a portion of a spherical surface. Obtaining these parameters requires a precision phase comparator at a working frequency of 2.5 GHz. The comparator consists of an arrangement of four couplers of 3 dB, one phase shifter of 90° followed by filtering and detection circuits such that one obtains: (Φl–Φ2) = arctanV1/V2, whereV1andV2are measured directly. The realised system permits a phase measurement with an error of less than 5° at the nominal frequency (2.5 GHz) for levels of power between −10 dBm and −30 dBm.

DOI:10.1049/ip-h-2.1986.0032

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The paper deals with the analysis of a new class of microstrip slotline ring 3 dB directional couplers which possess topological symmetry with respect to two of the input ports. Slotline or slotline microstrip T-junctions are used to obtain the frequency independent 180° phase shift. This provides for a high frequency independent isolation between the input ports. In the analysis effects of microstrip T-junctions and impedance transformation in the microstrip slotline transitions have been taken into account. The numerical results obtained predict that couplers operating over 30–50% bandwidth are feasible. Some additional design flexibility resulting from the coupler impedance transformation properties has also been demonstrated.

DOI:10.1049/ip-h-2.1986.0033

出版商:IEE    

年代:1986

数据来源: IET

摘要:

For versatile connections in an MIC circuit, an interdigital microstrip capacitor may be considered as a four-port network with some open ports instead of a straight two-port one. The impedance of the four-port network can be simple, up to its resonant frequency, based on some simple expressions for the even- and odd-mode capacitances for microstrip fingers.

DOI:10.1049/ip-h-2.1986.0034

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A simple analysis of thin annular-ring microstrip antennas (AR-MSA), along with a design technique that yields the optimum ring dimensions which maximises the radiation efficiency and the bandwidth, is presented in this paper. Using the cavity model, exact closed form solutions for the radiation fields are derived. The antenna fields distribution, resonance dimensions, radiation patterns, directivity, radiation conductance, quality factor and bandwidth are investigated for the different TMnmmodes. AR-MSAs operated at the high order TMn2modes are found to have better radiation properties and broader bandwidths than the corresponding disk-MSAs. A design table for the optimum ring dimensions for different types of the dielectric substrate material is also given in the paper.

DOI:10.1049/ip-h-2.1986.0035

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A simple approximation method to calculate scattering from a thin strip grating of a finite size is proposed for arbitrarily polarised incidence with an arbitrary plane of incidence. First, the grating is projected on the plane normal to the direction of incidence. The grating parameters are transformed at the same time according to a simple rule. Then, reflection and transmission coefficients for a plane wave are readily calculated for the fictitious problem of normal incidence on the projected grating. Equivalent electric and magnetic currents are derived using these coefficients at every point on the actual grating. Finally, integration of these equivalent currents over the actual grating gives the scattering of an arbitrary wave from a grating of arbitrary size and shape. The accuracy and validity of this method are also verified by experiments, where an arbitrarily-oriented grating is illuminated by either a plane or a spherical wave.

DOI:10.1049/ip-h-2.1986.0036

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The paper presents a technique for transforming linearly constrained broadband time-domain processors to an unconstrained partitioned form via an orthogonal decomposition of the constraint matrix. It is shown that the partitioned structure drops out naturally from solving the mathematics of the transformed unconstrained, optimisation problem. This approach enables the relationship between the Frost-type processor and the unconstrained partitioned processor to be established in a direct way.

DOI:10.1049/ip-h-2.1986.0037

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The problem of synthesising a reflector surface to produce a prescribed far-field radiation pattern when illuminated by a point source feed is treated using the complex co-ordinate method of Westcott. The far-field boundary value problem is formulated on a Cartesian grid and the solution technique demonstrated for two example specifications typical of satellite communication systems. The potential of the design approach is examined through diffraction analysis of shaped antennas derived from the example solutions.

DOI:10.1049/ip-h-2.1986.0038

出版商:IEE    

年代:1986

数据来源: IET