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A phased array antenna, used for shaping and steering the main antenna beam electronically to chosen directions within the predefined field of view, has been the key antenna system for satellite communications and military radars for decades. However, despite its high functional performance, it is still a very costly and complex solution for emerging wireless consumer applications such as high speed wireless communication and driving assistance systems due to the number of phase shifters and their complex control circuitry. Even more challenges are encountered with an increase in the number of channels if an antenna with high directivity is desired, such as routing RF and IF circuits, isolation of neighboring RF channels or calibration of a whole system.In order to eliminate the challenges stated above, a novel beam steering approach is presented in this dissertation based on the superposition of two squinted antenna beams. The two antenna beams are realized by exciting the opposite feeds of a dual-fed array antenna. A change in the phase difference and amplitude ratio between the input signals, using only one phase shifter and two variable gain amplifiers or only two I-Q vector modulators, steers the main beam in different directions. Due to its similar architecture, it exhibits all the advantages that a traveling wave antenna possesses as well, such as beam steering with the change of the operating frequency.Additionally, the sum and difference patterns can be obtained using this concept, allowing for an amplitude-comparison monopulse operation with a broad peak or a deep null at the broadside. Using this approach, beam nulls can also be steered towards interference directions, while keeping the shape and direction of the main beam unchanged. Another advantage is its high robustness against phase and amplitude errors due to analog hardware components in the RF path, which cannot be avoided in conventional phased arrays. A channel mismatch and crosstalk between neighbor RF channels or a temperature and time dependent array calibration can be minimized via this technique thanks to its unique topology, as well.In this work, an analytic antenna model has been derived and implemented in MATLAB using closed form expressions to analyze and optimize each relevant antenna parameter. Using this model, the development time becomes significantly shorter and the required computer memory is almost negligible.In order to prove the validity of the proposed novel beam steering approach, two different millimeter-wave (mm-wave) dual-feed antenna setups have been designed and implemented. In the first setup, commercial passive WR-10 components are used to perform the phase and i -iiamplitude changes manually. To demonstrate the full capability of electronic scanning, a second setup is built by employing an I-Q vector modulator instead of the waveguide phase shifter and the attenuator, which is controllable via input current signals. A mm-wave baredie transceiver MMIC which houses an integrated I-Q vector modulator in its ...

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