Radiation Energy and Mutual Coupling Evaluation for Multimode MIMO Antenna Based on the Theory of Characteristic Mode

Abstract

This paper presents a novel method to evaluate radiation energy and mutual coupling in multimode antennas. Based on the theory of characteristics mode, how much each mode occupies the radiation and the mutual coupling from each feeding port is calculated with the modal energy occupied coefficients. Furthermore, the linear transformation of feeding network in multimode antenna system has been adopted to complete the modal-based method. Then, this method is utilized to analyze and decrease the mutual coupling between feeding ports. Hence, a hexagonal wideband antenna is proposed with its evolution process and measured to validate the proposed method. The presented hexagonal antenna is a four-port multimode antenna consisting a planar hexagonal plate, vertical tapered baluns, and feeding network at the ground plane. The whole antenna works in 3-6 GHz and all its four ports are well matched with high port-to-port isolation.

PCB-Based Design of a Beamsteerable Array With High-Gain Antennas and a Rotman Lens at 28 GHz

“…Characteristic modes have been used to design MIMO antennas with isolated modes for user devices with a small ground plane [27,28,47,48]. Antenna decoupling has been studied with characteristic modes by calculating the modal admittance between modes and using reactive loading to suppress the unwanted modes [49,50]. However, these methods rely on calculating the modal admittance and selecting suitable loads for the arbitrarily placed parasitic elements.…”

Characteristic Mode Theory of Wavetraps for Antenna Decoupling

“…Figures 14 and 15 show the magnitude and phase of the y-component of the fundamental characteristic mode near-field E 1 of a 120 mm wide wavetrap. The optimal a 1 for cancellation is then found by plotting (14) in Fig. 16.…”

“…Therefore, in this paper, only the fundamental mode is used in the analysis to ease understanding. For added accuracy, higher order modes can be also included in the analysis, as expressed in the summation in (14).…”

“…Characteristic modes have been used to design MIMO antennas with isolated modes for user devices with a small ground plane [10]- [12]. Antenna decoupling has been studied with characteristic modes by calculating the modal admittance between antennas and using reactive loading to suppress the unwanted modes [13], [14]. In [15], the eigenvalues of mutually coupled modes were noted to reduce when a parasitic resonator was added.…”

Diseño de lentes metálicas usando la teoría de modos característicos.

“…Los estudios recientes tomando como referencia esta Teoría han desarrollado aplicaciones más amplias en el diseño de antenas, como por ejemplo, la síntesis de la forma de antenas compactas [111,112], el análisis de estructuras canónicas como cilindros o esferas [113], el análisis del ancho de banda de una agrupación de 2 × 2 elementos [114], el análisis de una antena de bajo perfil formada por una metasuperficie compuesta por tres capas metálicas sobre un plano de tierra y una línea microstrip [115] o el diseño de un sistema multiantena integrado en un modelo de avión militar [116]. Además, debido a la creciente demanda de dispositivos de comunicaciones móviles, el uso de la TMC ha ayudado a proponer un método de integración de un sistema de múltiples antenas para MIMO masivo (UWB Massive MIMO) [117][118][119], y en la mejora de la radiación en un sistema de antenas de cuatro puertos, que utiliza metasuperficies formadas por parches cuadrados [120].…”