摘要:

The linearity requirements and the design of an amplifier for a 64 QAM digital radio are described. A partial phase compensation between the cascaded bipolar transistor and FET amplifying stages helps to achieve bit error rates better than 10−20.

DOI:10.1049/ip-h-2.1988.0070

出版商:IEE    

年代:1988

数据来源: IET

摘要:

The application of feedforward linearisation to a 950 MHz, 1 W solid state amplifier described. Results are given for a series of twotone intermodulation distortion measurements. The effects of amplitude and phase errors in the linearisation circuit are also measured. It is shown that a 25 dB improvement in the intermodulation margin can be achieved over a bandwidth adequate for microcellular radio systems.

DOI:10.1049/ip-h-2.1988.0071

出版商:IEE    

年代:1988

数据来源: IET

摘要:

Rectangular half-wavelength microstrip antennas, fed by a coaxial line at the centre of one of the radiating edges, are treated as lossy transmission lines open-circuited at one of the ends. Closed form expressions are developed by which the input impedance of these antennas may be very accurately computed.

DOI:10.1049/ip-h-2.1988.0072

出版商:IEE    

年代:1988

数据来源: IET

摘要:

Other researchers have proposed sixport reflectometer calibration procedures that require only four standards. The memorandum describes an alternative approach to the implementation of such a calibration routine. The standards required are a matched load, a short circuit and two offset terminations. Laboratory tests indicate that measurement accuracies of within ±0.01 in magnitude and within ±1° in phase can be obtained.

DOI:10.1049/ip-h-2.1988.0073

出版商:IEE    

年代:1988

数据来源: IET

摘要:

The resolution and dynamic range performances of a forward-scattering tomographic imaging technique are evaluated by a computeraided reconstruction of the point spread function (PSF), first for a strictly theoretical case and then, taking into account the effect of certain parameters, for real experimental conditions. The width of the main lobe of the PSF is considered as an index of the resolution power of the technique; the ratio between the peak value of the PSF and the maximum value of the ambiguity artifacts is considered as an index of the dynamic range of the technique. The results obtained are summarised in order to be able to appreciate the changes in the features of the PSF as functions of the number of different views, the distance of the scanning area from the rotation axis of the object to be imaged, and the size of the scanning area.

DOI:10.1049/ip-h-2.1988.0074

出版商:IEE    

年代:1988

数据来源: IET

摘要:

This short paper deals with the positions and magnitudes of fixed phase shifters used in Butler matrices with 90×° hybrids. These matrices are symmetrical networks which produce phase shifts that are odd multiples of π across the output ports. Simplified design procedures are detailed for positioning the fixed phase shifters, and their magnitudes are given for a 32 × 32 matrix. A 16 × 16 matrix is also shown and procedures for a matrix of any order are indicated.

DOI:10.1049/ip-h-2.1988.0075

出版商:IEE    

年代:1988

数据来源: IET