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J. Ilouno ¹, B. J. Kwaha ², A. M. Batu ³

Affiliations
1 Department of Remedial Studies, University of Jos, Jos, NG
2 Dept. of Physics, University of Jos, Jos., NG
3 Department of Science and Technology, Kaduna Polytechnic, NG

Abstract

In this paper, channel attenuation (link loss) and fiber loss budget for different types and sizes of optic fibres in selected applications in RF communications were measured and computed using relevant equations to ascertain accuracy of measurements and also for comparison sake. The results obtained agree with each other. The minor differences in values noticed in comparing the calculated and manufacturer's values make only a negligible impact in practical RF communication. In line with theory, the computed values show that channel attenuation increases as distance increases. Multi-mode fibers with smaller core diameters offer less attenuation. Multi-mode fiber operating in 1300 nm wavelength for application 100G-M-SN-I (500 m supportable distance) gives 2.95 dB compared to 850 nm fiber with 3.90 dB of the same size. Single-mode 1550 nm fibers offer less attenuation compared to 1310 nm fibers. Furthermore, the measured values of attenuation of different optic fiber colours at Zain, Abuja upholds the manufacturers' assertion that turquoise, red, brown, pink, and green fiber coatings are good for indoor connectivity while white, black, yellow, blue and orange are recommended for outdoor transmissions.

Keywords

Fibre Optics, RF Applications, Channel Attenuation

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B. J. Kwaha ¹, E. A. Kolawole ¹, A. M. Batu ²

Affiliations
1 Dept. of Physics, University of Jos, Jos., NG
2 Dept. of Science and Technology, Kaduna Polytechnic, NG

Abstract

This research compares two IIR digital filter design and implementation methods- viz MATLAB direct method and Bilinear transformation method. Programs to design and implement Butterworth IIR lowpass digital filters were developed and executed using both methods. In the design, at F_pass of 1Hz, F_stop of 2.414 Hz, using MATLAB method the 3 dB frequency is at 1.605 Hz while using the Bilinear transformation method the 3 dB frequency is at 1.395 Hz. At F_pass of 0.7839Hz, F_stop of 2.007 Hz, using MATLAB method the 3 dB frequency is at 1.181 Hz while using the Bilinear method the 3 dB frequency is at 1.001 Hz. From the design it was observed that the Butterworth filter has maximally flat passband in its frequency response and a poor roll-off at its bandstop which is in line with predicted theory. The Butterworth filters designed using Bilinear transformation were more stable with a monotonically decreasing gain response due to its poor roll-off which may be associated to discrete component performance. The magnitude of the passband decreases as the order of the filter increases. The designs also show that higher order filters have sharper skirts and may be used in phase modulated wave (PMW) applications.

Keywords

Matlab, Bilinear Transformation Methods, Filter Design

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B. J. Kwaha ¹, O. M. Durodola ¹

Affiliations
1 Department of Physics, University of Jos, NG

Abstract

A comparative analysis of 5 different aluminum cable types tagged J₁, J₂, J₃, J₄ and J₅, from 5 different cable manufacturing companies was carried out using 2 different test methods namely- x-ray fluorescence spectrometry (XRFS) and resistivity test with the main objective of ascertaining why some cables of the same gauge fail under the same load levels. Purity levels, resistivity and conductivity checks were performed. Equal dimensions of 5 cable brands were sampled and ground to fine powder. The percentage purity of each sample was determined through XRFS test. One set of similar samples was subjected to resistivity test. XRFS result shows that J₁ had purity of 99.30%, J₂, 99.10%, J₃, 98.50%, J₄, 99.20% and J₅, 98.80%. The cable types also had resistivity and conductivity values respectively as for J₁ [2.324x10^-9 Ω m&430.29x10⁶ (Ωm)^-1], J₂ [3.921x10^-9 Ω m&255.04 x 10⁶ (Ωm)^-1], J₃ [2.689 x 10^-9 Ω m&371.89 x 10⁶ (Ωm)^-1], J₄ [2.614x10^-9 Ω m&382.56x10⁶ (Ωm)^-1], and J5 [2.890x10^-9 Ω m&346.60 x 10⁶ (Ωm)^-1]. Comparing these values to the standard resistivity value of pure aluminum [2.82 x 10^-8 Ω m] it would be seen that these results are in agreement with theoretically computed values. The XRFS test used in this research could be used to test the purity of aluminum before stretching into cables. It can also be used to determine the standard of aluminum products. The electrical resistivity test could be used to determine and set a standard resistivity and conductivity requirements to be met by different cable brands and types used in electric power distribution so as to curb the menace of cable failure and electric hazards.

Keywords

Qualitative Analysis, Aluminum, Cable Types

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L. Okwara ¹, B. J. Kwaha ¹, P. Amalu ²

Affiliations
1 Department of Physics, University of Jos, NG
2 Department of Physical Sciences, Ajayi Crowther University, Oyo, NG

Abstract

In this paper, an array dipole antenna adaptable to VHF and UHF bands was designed and constructed. The dimension (length and spacing) of the parasitic elements (directors) were determined: the longest length being 17.0cm and the shortest 5.3cm. The widest spacing was 3.58cm and the shortest 1.27cm. The characteristics of the antenna were determined at a frequency of 189.5MHz. It has an input impedance of 96.72Ω and a gain of 2.15dBi. It performs optimally in frequency range of 60MHz- 300MHz as attested using TV (receive only) monitor. It adapts favourably well to the VHF and lower UHF bands.

Keywords

Dipole Antenna, Design

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