Design and analysis of a low‐profile directive antenna array for multi‐element terminals

Abstract

The authors verify the benefits of directivity for a 4 × 4 multiple‐input multiple‐output (MIMO) system in a non‐line‐of‐sight indoor propagation environment. A novel prototype with four directive antennas has been designed to have full aggregate azimuth coverage, which is conveniently achieved without the need for electronic or mechanical beam‐steering. In this way, it captures similar multipath content to that of an equivalent omnidirectional device as confirmed by the field measurements. This coupled with the inherently larger gain of directive antennas renders the prototype a better choice for multi‐antenna receivers. The prototype design makes it possible to use a simple but effective power‐based antenna selection algorithm. Importantly, this algorithm achieves close to the theoretical maximum channel capacity when only two radio frequency chains are available at the receiver. For the first time, these results show that in an MIMO indoor environment directive receive antennas are a viable option.

Compact Size MIMO Amer Fractal Slot Antenna for 3G, LTE (4G), WLAN, WiMAX, ISM and 5G Communications

“…The design of the proposed MIMO used an Amer fractal slot structure to provide multiple paths for the surface current, where each path creates its own resonant frequencies, which together achieve a wide operating band. Some of these paths are perpendicular to each other, which causes circular polarization characteristics, low mutual coupling between the opposite ports (1 and 3, 2 and 4) for all operating bands (nearly 1.5-30 GHz) and less than -10dB for all neighbor ports at frequency band (15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30). The measured efficiency varies between 50% and 85%, and low profile in compact size.…”

“…However, this antenna has low gain values at lower bands and low efficiency. The antennas reported in [2], [7], [8], [9], [13], [16], [17], [19], [20], and [23] are large and thus cannot be used in modern portable communication devices. Conversely, previous antennas that are small in size also have low efficiency or gain, such as [4], [5], [10], [12], and [21].…”

Novel sunflower MIMO fractal antenna with low mutual coupling and dual wide operating bands

“…El), impedance bandwidth, efficiency, gain, mutual coupling ( S ij ), and size. Previous MIMO antennas were either too large such that they cannot be used in modern portable communication devices [2, 6, 7, 8, 13, 14, 16, 17, 19, 20, 21, 29, 30], or small but cannot support the requirements of modern communication networks, such as 3G, WLAN, LTE, and WiMAX [3, 10, 12, 15, 18, 22, 23, 25, 27, 28].…”