Ultraspherical tapers

Tapered transmission lines for impedance matching at microwave frequencies are obtained from quarter-wave transformers using ultraspherical polynomials. It is shown that a free parameter can be suitably chosen so as to optimise energy transmission.     

Lowpass filter with minimum integrated power-loss ratio in the passband

A class of lowpass filters with minimum integrated power-loss ratio in the passband is discussed. Comparisons with the usual Butterworth and Cheby?shev filters are also reported.     

Legendre tapers

A new class of tapered lines using Legendre polynomials is discussed. The main advantage of such a device is the high value of the major/minor lobes ratio for the reflection coefficient, especially for frequencies much higher than the cutoff value.     

Synthesis of filters with minimum integrated power-loss ratio in the passband

The synthesis of filters with minimum integrated power-loss ratio in the passband is reported. The experimental results obtained with the passband filters realised at microwave frequencies are discussed.     

General class of multisection quarter-wave transformers for impedance matching at microwave frequencies

A general class of multisection quarter-wave transformers for impedance matching is presented. The main advantages of these new devices are the flatness condition at the central frequency value and a minimum excess loss, integrated with respect to a given weighting function in any frequency interval in the passband.