Investigation of tightly coupled arrays for wideband applications

Arda, Kaan
This thesis aims to provide in depth research on tightly coupled dipole arrays to be used in ultrawideband apertures applications. First, operation principles of tightly coupled dipole arrays are investigated. Starting from the Wheeler’s current sheet aperture concept, some calculations on bandwidth and impedance concepts are conducted. B.A. Munk’s addition to the concept, use of capacitive elements between adjacent dipoles, are introduced. Array unit cell is modeled using equivalent circuit approach, bandwidth and input impedance calculations are conducted using MATLAB environment. Unit cell designs using two different capacitive coupling mechanisms are given. Optimized final unit cell products that satisfy theoretical bandwidth and pattern requirements are given. Simulations are conducted for determination of number of resistive terminations in tightly coupled arrays. Discussions on number of dummy elements are given. Series of example finite array analyses are conducted. A finite array design that is producible using PCB technology is given. Antenna unit cell is modified in a finite array environment, due to the fact that finite PCB size that restricts maximum number of elements. An ultrawideband aperture that satisfies the theoretical limits is designed using this finite aperture area. Different array feeding mechanism are given to be used as proposed antenna’s feed. Various kinds of feed mechanisms are investigated, only a portion amongst them are determined that they do perform well. Manufacturing process of finite array is given along with the measurement results. Similarity between measurements and simulations are discussed.