Tanawut Tantisopharak

Identification of maturity of fruit in the frequency domain using its natural frequencies

This paper presents an identification methodology to determine the stage of maturity of a fruit by using its natural resonant frequencies, which can be extracted from its scattering response. Since the dielectric properties of a fruit are determined by its chemical properties, the identification can be performed by comparing the libraries of poles to determine the stage of maturity for that fruit.

Nondestructive Determination of the Maturity of the Durian Fruit in the Frequency Domain Using the Change in the Natural Frequency

This paper proposes a nondestructive technique to determine the stages of maturity of durian fruits. The presented methodology utilizes the electromagnetic scattering properties from the fruits over time for identification of the stage of maturity using its natural frequencies. Both simulation and experimental results show that the natural frequencies in the scattering responses change with the maturity of the durian fruit. Particularly, the change in the fundamental resonant frequency is used as a possible identification criterion for characterization of the stage of maturity. This is because the dielectric constant of the core of the fruit changes with its degree of maturity. In addition, the experimental results indicate that the variation of the dominant resonant frequency of durian fruits varies at different stages of maturity and this has the potential to be applied as a criterion to identify the stages of maturity.

Simple initialization scheme for CMA adaptive antenna by using digital beam synthesis

This paper presents a simple technique of initialization for CMA adaptive antenna. The technique utilizes digital beam synthesis for a circular array antenna to synthesize the beams in digital domain. The synthesized beam can be switched into different directions by choosing proper weight vectors. The weight vectors are calculated through a phased array principle. The beams obtained from the synthesis are employed to initial CMA in order to improve its convergence property. The technique makes the compact adaptive antenna using CMA possible. Simulation results show that the proposed technique can significantly improve the convergence property of CMA.

A Dual-Band Dual-Feed Switched-Beam Patch Antenna for WLAN Application

Due to the demand of dual-band modern wireless communications, this paper presents a dual-band patch antenna for IEEE802.11 a and g wireless local area network (WLAN) system, The antenna has bidirectional patterns that can be switched by an RF switch to select the feeding probe positions. The 2.4GHz and 5.2GHz patches are stacked on a ground plane and are matched to the RF switch by open stubs. Analysis and design are illustrated and throughput improvement is demonstrated in an indoor environment.

Investigation of the natural resonant frequencies of palmyrah palm juice for quality control

This paper proposes an identification methodology to distinguish between pure and adulterated palmyrah palm juice. The resonance behavior of the palmyrah palm juice has been investigated through numerical electromagnetic simulation. From the scattered response, the natural frequencies of the palmyrah palm juice are extracted. The identification can be performed by cataloging and comparing these pre computed library of the natural resonant frequencies associated with the standard palmyrah palm juice to check for the quality of the samples to be tested.

Wordlength effect on CMA adaptive antenna with digital beam synthesis initialization

This paper investigates the wordlength effect on the CMA adaptive antenna with digital beam synthesis initialization. The antenna is a four-element circular array whose main beam can be switched into different directions by using digital beam synthesizer. A beam obtained from digital beam synthesis is exploited as an initial beam for CMA. A weight vector for generating initial beams of CMA is chosen by determining radiation patterns. The SINR of the digital beam synthesis-based CMA adaptive antenna with different wordlengths are shown. Moreover, the step-size constant of CMA is also investigated and properly chosen to avoid underflow and overflow phenomena.

Parallel multistage CM array with constrained initialization of digital beam synthesis

A technique which assists initialization for the parallel version of multistage of constant modulus (CM) array is discussed. The technique employs weight-multiplication to generate a group of the initial beams for CM array. Each signal is recovered by the individual CMA stage along with digital beam synthesis where the initial main beam directs close to the signal direction. Simulation results are shown and the proposed multistage CM array recovers all signals received by the antenna. However, the system may encounter the ambiguity for rejecting signals if incoming signals are very close. This problem is resolved by using a narrow-beamwidth antenna.