Ronald L. Fante

Intensity scintillations of an EM wave in extremely strong turbulences

If one assumes Gaussian field statistics in extremely strong turbulence, the scintillation index of an arbitrary source approaches unity. This result is independent of whether the source is coherent or incoherent, provided that the response time of the measuring apparatus is short compared with the coherence time of the source.

Multiple-frequency mutual coherence functions for a beam in a random medium

By using the phase-screen approximation along with the extended Huygens-Fresnel principle, we have developed a method for computing the multiple-frequency mutual coherence functions for an arbitrary beam propagating in a random medium.

Some results on the effect of turbulence on phase-compensated systems

We have studied the effect of residual log-amplitude fluctuations and imperfect phase compensation on the characteristics of a phase-compensated optical link operating through atmospheric turbulence.

Some results on the imaging of incoherent sources through turbulence

We have studied how turbulence influences one’s ability to determine the spatial-frequency composition of an incoherent source by use of irradiance or speckle interferometry. We have found that results obtained by using these methods are not significantly affected by the turbulence for the case of high spatial frequencies; however, the lower frequencies may be affected considerably.

Comments on a method for processing stellar speckle data

This letter addresses methods for reducing stellar speckle interferometry data that require obtaining both the average autocorrelation and cross correlations of these speckle patterns. It is shown that these procedures degrade low-frequency results, in particular, those frequencies near the long-exposure atmospheric cutoff.

Probability of Detecting a Fluctuating Target Immersed in Both Noise and Clutter

The probability of detecting either a Swerling 1 or Swerling 2 target immersed in both Rayleigh-distributed noise and log-normally distributed clutter is calculated. Results are presented which demonstrate the effect of noise-to-clutter ratio, signal-to-noise ratio, and number of pulses integrated on the detection statistics.

A parabolic cylinder antenna with very low sidelobes

A method for designing an offset-fed parabolic cylinder antenna which has sidelobes of -50 dB or less over a 15-percent frequency band is presented. The designed antenna was built and tested, and shown to have approximately -46-dB sidelobes, although over a slightly different band than designed for.

An analysis of the elliptical reflector

The distribution of the electromagnetic fields diffracted by an elliptical reflector which is fed by a line source at or near one of its two foci is studied. For the elliptic cylinder the magnitude of the fields near the foci, the size of the focal region, the displacement of the focal spot as a function of the source displacement, and the application of the method of stationary phase in calculating the fields at points distant from either focus are calculated. Explicit results are presented for the fields as a function of the eccentricity of the ellipse and the angles subtended by the reflector edges.

Near-field distribution of a paraboloidal reflector

A major problem in communication antenna design is to obtain maximum gain and efficiency from large reflector antennas; few paraboloidal or dish antennas have efficiencies greater than 70 percent. The basic problem is the spreading of power by the source feed located at or near the focus of the reflector, which causes a concentration of power near the center of the aperture. In order to determine what kind of field distribution is required in the feed region to produce a uniform distribution over the reflector the authors have studied the inverse problem of a plane wave incident normally upon a paraboloidal reflector

Interference suppression via operating frequency selection

Spectral analysis of the environment, often called sniffing, is used to find a clear operating band in radar and communication systems. The authors show that the sniffing technique can be used to null multiple broad-band sidelobe jammers by exploiting the transfer function of the antenna. Analysis and computer simulation are used to demonstrate the performance.