ABSTRACT
The normal definitions and equations for antenna parameters, such as gain and beamwidth, implicitly refer to parameters at a specific frequency and explicitly contain the wavelength. Consider a ultra-wideband pulse train as it leaves the transmitter. It passes through the transmit antenna and the atmosphere, is reflected at the target, passes through the atmosphere again, and is received by the receive antenna. The Fourier transform of a product of two functions is the convolution of the Fourier transforms of the two functions separately. A straightforward product of functions in the frequency domain becomes a convolution in the time domain of the Fourier transforms of those frequency functions, which is mathematically more difficult. An operational option would be to vary the timing of the transmitted pulses from the various segments of the linear array so as to counteract the distance factor and effectively “refocus” the linear array.
