Abstract
The modal-expansion method is employed to analyze an array of multiple monopole antennas. A perfectly conducting plate is introduced at the top of the monopole array to facilitate the modal-expansion analysis. Expansion coefficients in the field expressions are found by enforcing continuity conditions of the tangential field components across the regional surfaces. Cylindrical function's addition theorem is employed to realize the transformation of field expressions in different coordinate systems. Numerical results for theS-parameters of a two-monopole antenna are presented and they are in good agreement with experimental ones. Also examined is the effect of the distance between two monopoles on the antenna's mutual coupling and radiation pattern. A four-monopole antenna is studied for its beam-steering capability and simulated results for its radiation properties are compared with those obtained by high frequency structure simulator (HFSS).
Highlights
Monopole antenna arrays fed through an infinite ground plane by coaxial transmission lines are extensively used in various communication systems due to their desirable features, such as geometrical simplicity, low construction cost, polarization purity, and reasonable bandwidth [1, 2]
Monopole antenna arrays have been studied by many researchers using different methods, such as the integral equation method for coupled monopoles [6], the method of moments [7], and the radial guide field matching method (RGFMM) [8]
In order to examine the effect of the introduced boundary and the approximation made, a comparison between our modal-expansion results with high frequency structure simulator (HFSS) data for the S-parameters of a two-monopole antenna is conducted for various distances between the two monopoles
Summary
Monopole antenna arrays fed through an infinite ground plane by coaxial transmission lines are extensively used in various communication systems due to their desirable features, such as geometrical simplicity, low construction cost, polarization purity, and reasonable bandwidth [1, 2]. This paper applies the modal-expansion method to study the radiation characteristics of an array of multiple monopole antennas. Due to the fact that the coaxial feed line for monopole antennas can be equivalently represented by a small gap feed when the dimensional parameters of the coaxial feed line are electrically small [17], in this paper, we use small gap sources, rather than the practical coaxial feeds [15, 16], to simplify the mathematical formulation and numerical computation.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
