This paper presents one miniaturized circular patch antenna (1-CPA) instead of two CPAs to generate multimode patterns for multiple-input multiple-output (MIMO) communication systems. A suitable material composition using ferrite substrate materials is proposed. The proposed ferrite 1-CPA is tested using the FEKO simulator, and it is found that the size of the proposed ferrite 1-CPA can be significantly smaller, e.g., 25.7 times, than that of the recently developed dielectric twoCPAs stacked. However, the bandwidth of the proposed ferrite 1-CPA should be sacrificed by one quarter.

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Communication theory is one of the subjects that is mathematically intensive and involves memorizing numerous equations. This paper describes the use of Matlab and Simulink in teaching communication theory for undergraduate students. The objective of this approach is to provide an intuitive understanding of the theory without deeply sinking into derivations of formulae. Signal filtering is an inevitable step in every communication system. Generally, filter theory is a standalone course offered to graduate level students. Using amplitude modulation as a case study, usage of Fast Fourier Transform (FFT) is discussed in this paper. Frequency domain representation of a signal and ideal filtering that can be performed directly without applying much involved z-transform is presented.

This paper proposes an annular-ring microstrip antenna for a 2×2 MIMO communication system. A single annular-ring microstrip antenna with two feed probes is used to generate two orthogonal radiation patterns. Radiation pattern associated with each probe is generated by FEKO simulations and shown that the patterns are orthogonal to each other. Orthogonal radiation patterns are needed to exploit pattern diversity instead of space diversity. Miniaturization is achieved by using a ferrite substrate instead of using a pure dielectric substrate. A ferrite annular-ring antenna with a single feed probe was manufactured and tested. Also a ferrite single circular patch antenna was manufactured and measurement results are presented.

A pulsed ferrite magnetic field generator (FMFG) was designed for the use in the 1000 m long through-theearth (TTE) communication system for mining disaster situations. To miniaturize the TTE system, a ferrite core having 10,000 of permeability was used for the FMFG. Attenuation of the magnetic field intensity from the FMFG (200-turn and 0.18 m diameter) was calculated to be 89.95 dB at 1000 m depth soil having 0.1 S/m of conductivity. This attenuation was lower than 151.13 dB attenuation of 1 kHz electromagnetic wave at the same conditions. Therefore, the magnetic-field was found to be desirable as a signal carrier source for TTE communications as compared to the electromagnetic wave. The designed FMFG generates the magnetic field intensity of 1 × 10 −10 Tesla at 1000 m depth. This magnetic field is detectable by compact magnetic sensors such as flux gate or magnetic tunneling junction sensor. Therefore, the miniature FMFG TTE communication system can replace the conventional electromagnetic wave carrier type TTE system and allow reliable signal transmission between rescuer and trapped miners.