الفهرس 
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Abstract
The waveguide array antenna provides a number of advantages in many radar, remote sensing and satellite applications. The advantages are related with the antenna planar form, strength of the construction, high power operation capability, high efficiency, small thickness and weight. In this thesis, serpentine feeder has been introduced, designed and analyzed with enhancement transmission of the dominant mode TElo (Mode I) and depression of the higher modes TEol (Mode 2), TE20 (Mode 3); using different varieties of multimode extractor-converter structures and different multimode metamaterial (MTM) array structures. First, the proposed structure with multi mode extractor-converter presents TEIO enhancement transmission coefficient ratio up to 18.74, 22.44 and 26.56 for cylindrical, cone and horn transition waveguide channel (=::7-13.5 dB) compared to the conventional waveguide feeder. Also, the optimum two cells transition waveguide channel of mode extractor-converter structure has been presented. Second, the X-band guided waves structure, as array waveguide radar antenna feeder, with enhancement TElo transmission using multi-mode MTM array structures has been introduced, designed and analyzed. The proposed structure presents TElo enhancement transmission coefficient ratio up to 18.64 at port 2 and 14.3 at port 3 compared to the conventional guided waves through the use of the S-parameter retrieval techniques that have been utilized recently to characterize MTM. The goal is to realize the manipulation of permittivity (e) and permeability (/1) through specific inclusion of metal in dielectrics to achieve desired substrate properties in order to yield optimum radiation characteristics.
The proposed X-band waveguide structure without and with circular spiral MTM array structure, have been designed, fabricated and measured at antenna laboratory. The S¬parameter characteristics of the proposed structures are measured and compared with the simulated results which have an intuitive insight to how the structure operate with enhancement performance in the X-band and also in the C-band with X-band dimensions structure. Finally, Guided waves with enhancement TElo transmission and higher modes TEol, TE20 depression using multi-mode MTM array and multi-mode extractor-converter structures have been introduced, designed and analyzed .The proposed structure presents TElo enhancement transmission coefficient ratio up to 35.3 through different varieties of MTM array, mode extractor-converter structures and combined together.
Slotted waveguide array antenna (SW A) is a popular antenna in navigation, radar and other high-frequency systems. They have low-loss, high efficiency and radiate linear polarization with low cross-polarization. An application to the proposed structures in this thesis is the investigation and design of the X-band SW A structure using multi-mode MTM array and multimode extractor-converter structures has been introduced, designed and analyzed. The proposed structure presents TElo enhancement transmission coefficient ratio up to 22.44 with absolute bandwidth up to 720 MHz through different varieties of multimode MTM array, extractor-converter structures and combined together compared to the conventional guided waves. The proposed structure radiation characteristics for different varieties are obtained to demonstrate the performance. It was found that the proposed antenna is affected by the guided waves feeder structure and the MTM array structure embedded in either the feeder or the S WA.
All varieties have TEIO dominant mode enhancement transmission coefficient and higher modes depression but the variety choice depends on the desirable required achievements at the operating frequency band 11-12 GHz, such as, number of frequency bands, maximum absolute bandwidth, design structure area and cost. M iniaturization of a SW A using multimode MTM array structures rather than classical dielectric inclusion has been introduced, designed and analyzed for C-band frequency band to demonstrate the performance of antenna and the effect of MTM array in minimization the size of antenna. The RF pulse compression output power for different varieties compared with input power versus time in nsec have been obtained to demonstrate the enhancement energy incident into the array waveguide radar antenna. Thus the overall performance for the proposed waveguide array antenna will be more effective and reliable to meet the requirements for array waveguide modern radar antenna applications.