Date of Award

1-24-2024

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical Engineering and Computer Science

Advisor(s)

Jay Lee

Second Advisor

Jun Choi

Keywords

Antenna Array;Filtenna;Power Divider;Wideband

Abstract

The designs for broadband and multiband antenna feeds, specifically for antenna array applications, are fabricated and evaluated to optimize the performance of these arrays. A specific power divider functionality is expanded upon for layout flexibility and amplitude tapering. A method of multiplexing antennas is used to overcome limitations caused by element spacing in arrays. A planar power divider that has wide bandwidth performance (at least 30% BW) and uses resistors that are tied to ground is analyzed. This particular power divider has previously only been solved for the equal split 2-way case. This work simplifies the structure of the original design and then leverages that simplicity to expand the capability of the power divider for N-way, unequal spilt and wider bandwidth cases. A 4-way power divider, an unequal split power divider with a 2:1 power split ratio and wider band power divider with 50% bandwidth are all simulated and experimentally verified with fabricated prototypes. However, for wider bandwidth arrays (or multiband array covering a wide bandwidth) the spacing between antenna elements becomes an issue since it can only be optimized at a single frequency. A method to overcome this limitation is presented. This method uses separate antenna elements multiplexed with isolation circuits. These antennas are treated as a single element for the design of an antenna feed. This is demonstrated with a 3 band 1D scanning array prototype of patch antennas that is validated through testing. The concept is then expanded for 2D scanning by using frequency scanning antennas. Since frequency scanning antennas do not have a sufficient stop band needed for multiplexing, an antenna with improved out of band rejection is designed for use in this type of array. A prototype of this antenna is fabricated and validated through testing. This practical research is supported by extensive simulations and validation through prototypes. The measurements show good agreement with the simulations for the expanded power dividers showing their potential to be used in antenna feed networks. The multiband antenna array measurements show good agreement with simulation, proving it to be a good solution for array deployments. The frequency scanning antenna with improved out of band rejection measurements also shows good agreement with simulation, proving its potential to expand the previous multiband array to 2D scanning.

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Open Access

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