: Research was conducted to collect and describe out-of-band antenna pattern data. The research efforts were devoted (1) to deriving valid measured data for a reflector antenna for out-of-band frequencies spanning intervals around the second and third harmonics of the in-band design frequency and (2) to statistically characterize the measured data. The second harmonic data were collected for both polarization senses for the out-of-band frequencies of 5.5 GHz to 7.5 GHz in steps of 0.1 GHz. The third harmonic data were collected for both polarization senses for the out-of-band frequencies of 8.0 GHz to 10.0 GHz in steps of 0.1 GHz. Additionally, in-band data were collected at 2.9, 3.0, and 3.1 GHz for both polarization senses. The measured data were collected on the Georgia Tech compact antenna range test facility with the aid of an automated data logger system designed expressly for efficient collection of broadband antenna data. The pattern data, recorded directly on magnetic disks, were analyzed (1) to compute average gain and standard deviation over selected angular sectors, (2) to construct cumulative probability curves, and (3) to specify the peak gain and the angular coordinates of the peak at each frequency.

: During this program, a flexible, interactive program for Monte Carlo analysis of near-field and far-field fields of a prime focal fed out-of-band paraboloidal reflector antenna was developed and used for numerical simulation. The simulations are not sensitive to frequency only averaging. The distribution of the modal coefficient phases has the greatest effect on the numerically simulated patterns. The numerical simulations also indicate the validity of near-field ensemble measurements in far-field pattern prediction and the role of near-field correlation terms in these patterns.

The transmit beam and radiation efficiency for 10 metersquare subarray panels were quantified. Measurement performance potential of far field elevated and ground reflection ranges and near field technique were evaluated. The state-of-the-art of critical components and/or unique facilities required was identified. Relative cost, complexity and performance tradeoffs were performed for techniques capable of achieving accuracy objectives. It is considered that because of the large electrical size of the SPS subarray panels and the requirement for high accuracy measurements, specialized measurement facilities are required. Most critical measurement error sources have been identified for both conventional far field and near field techniques. Although the adopted error budget requires advances in state-of-the-art of microwave instrumentation, the requirements appear feasible based on extrapolation from today's technology. Additional performance and cost tradeoffs need to be completed before the choice of the preferred measurement technique is finalized.

: Theoretical and numerical analyses were performed to study the application of near-field theory and techniques to characterize the radiation and coupling characteristics of wideband, in-band and out-of-band pulsed or cw radiating systems. Specifically, theory and equations were developed for characterizing the radiation patterns of wideband cw or pulsed antennas over both in-band and out-of-band frequency intervals from measured data collected via near-field measurement techniques. The results are applicable to either phased array or reflector antennas. Three analytical techniques for analyzing the in-band and out-of-band coupling between pairs of cosited antennas were studied. The three techniques are (1) the Plane Wave Spectrum (PWS), (2) the Spherical Wave Spectrum (SWS), and Geometrical Theory of Diffraction (GTD). The existing theory and equations that are applicable to selected common waveguide components under normal in-band operation were extended to describe wideband out-of-band responses. Also, the theory and equations were formulated for computing the higher-order mode coefficients at the aperture of a waveguide radiating element from a knowledge of the measured far-field electric field of the radiating element when surrounded by a large conducting ground plane.

Empirically derived curves which display the effects of near-field antenna coupling in the presence of metal obstacles are presented and discussed. The changes in boresight coupling between near-field antenna pairs due to intervening sharp-edged metal sheets and round metal cylinders of various sizes located at intermediate ranges between the antennas were measured for three antenna separation ranges. The measurements were performed with each antenna pair same-sense polarized for both horizontal and vertical polarizations at C-band and X-band frequencies. The effects of various parameters such as the antenna separation distance, type of obstacle, size of obstacle, location of the obstacle between antenna pair, polarization, frequency of operation, and ratio of the transmitting aperture dimension to the receiving aperture dimension are observed in the families of empirical curves.