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Previously, it has been shown that the projection method can be used as an effective tool to compute the appropriate phase compensation of a conformal antenna array on a spherical surface. In this paper, the projection method is used to study the gain limitations of a phase-compensated sixelement conformal microstrip antenna array on non-conducting spherical surfaces. As a metric for comparison, the computed gain of the phase-compensated conformal array is compared to the gain of a six-element reference antenna on a flat surface with the same inter-element spacing and operating frequency. To validate these computations, a conformal phased-array antenna consisting of six individual microstrip patches, voltage controlled phase shifters and a power divider was assembled and tested at 2.22 GHz. Overall, it is shown how much less the gain of the phase-compensated antenna is than the reference antenna for various radius values of the sphere.

A vector modulator based phase shifter is developed using 0.18um CMOS process at Sband frequency to be integrated into a conformal phased array antenna to recover the desired radiation pattern in the entire 360° range. The phase shifter has a variable gain amplifier integrated into the circuit in order to vary gain along with phase for precise control to correct the degraded radiation pattern due to the conformal shaping. The results show state-of-the-art performances including more than 7dB conversion gain with variable feature, a continuous phase rotation of 360° with steps as low as 11.25° and very low power consumption of 17mW, for the first time to the best of the authors' knowledge. The chip size including all pads is 1.5mm X 0.75mm. iv ACKNOWLEDGEMENTS Firstly, I would like to thank my academic advisor, Dr. Debasis Dawn for his continuous support, patience and guidance in helping me complete my research work. I would also like to thank Alfonso Mendoza Radal for his support and guidance while working on my research work. ND NASA EPSCoR has supported this project under the agreement FAR0020852. I would like to thank Prof. Benjamin D.

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