Finite length of sequences that are modulated both in phase and amplitude and have an ideal autocorrelation function (ACF) consisting of merely a pulse have many applications in control and communication systems. They are widely applied in control and communication systems, such as in pulse compression systems for radar and deep-space ranging problems [1-5]. In radar design, the important part is to choose a waveform, which is suitable to be transmitted because the waveform controls resolution in clutter performance. In addition, it can solve a general signal problem particularly related to the digital processing. Energy ratio (ER), total side lobe energy (SLE), and peak sidelobe level (PSL) are three properties of such sequences interest. This paper presents a method using the Complementation, Cyclic Shift and Bit Addition for synthesizing and optimizing a binary sequence implemented to improve the sequences of a similar quality with the Barker sequence, particularly for lengths greater than 13. All of these methods are guided by the specific parameter with good characteristics in ACF (ER, SLE, and PSL) [6,7,8]. Such sequences can then be effectively used to improve the range and Doppler resolution of radars.
Agriculture waste is potentially useful as an alternative material to absorb and attenuate electromagnetic interference (EMI). This research highlights the use of coconut shell powder (CSP) and coconut shell activated carbon (CSAC) as raw materials with epoxy resin and amine hardener composite to absorb microwave signals over frequency of 1 -8 GHz. In order to investigate the suitability of these raw materials as EMI absorbing material, carbon composition of the raw materials is determined through CHNS Elemental Analysis. The surface morphology of the raw materials in term of porosity is investigated by using TM3000 Scanning Electron Microscope (SEM). The complex permittivity of the composites is determined by using high temperature dielectric probe in conjunction with Network Analyzer. From the result, the Carbon% of CSP and CSAC is 46.70% and 84.28% respectively. In term of surface morphology, the surface porosity of CSP and CSAC is in the range of 2 µm and 1µm respectively. For the dielectric properties, the dielectric constant and the dielectric loss factor for CSP and CSAC is 4.5767 and 64.8307and 1.2144 and 13.8296 respectively. The materials more potentially useful as substitute materials for electromagnetic interference (EMI) absorbing are discussed. Keywords: agricultural wastes, dielectric properties, carbon composition AbstrakSisa pertanian mempunyai potensi untuk digunakan sebagai bahan alternatif untuk menyerap atau melemahkan gangguan elektromagnatik (EMI). Kajian ini menekankan kepada penggunaan serbuk tempurung kelapa (CSP) dan karbon teraktif tempurung kelapa(CSAC) sebagai bahan mentah dengan campuran resin epoksi dan komposit penguat amina untuk menyerap gelombang mikro dalam frekuensi 1 -8 GHz. Bagi mengkaji kesesuaian bahan mentah sebagai bahan penyerap gelombang mikro, komposisi karbon dalam bahan mentah ditentukan mengunakan analisis unser CHNS. Liang permukaan bahan mentah pula dikaji mengunakan mikroskop pengimbas elektron TM3000 (SEM). Ketelusan kompleks bagi bahan campuran diukur menggunakan prob dielektrik suhu tinggi dan alat analisis rangkaian. Daripada keputusan yang diperolehi, peratusan karbon dalam CSP dan CSAC adalah sebanyak 46.70 % dan 84.28 %. Manakala dari segi liang permukaan pula, keliangan CSP dan CSAC masing -masing berada dalam lingkungan 2um dan 1um.Bagi sifat dielektrik, pemalar dielektrik untuk CSP dan CSAC masing -masing adalah 4.5767 dan 64.8307. Bagi pembelauan dielektrik, nilai untuk CSP dan CSAC masing -masing adalah 1.2144 dan 13.8296. Isu bahan yang lebih berpotensi untuk digunakan sebagai bahan penyerap gangguan elektromagnatik (EMI) dibincangkan.
In this study, we proposed a bio-inspired technique known as modified cuckoo search (MCS)-based weighted sum algorithm towards synthesizing symmetric linear array geometry with minimum side lobe level (SLL) and/or nulls control. The newly evolved metaheuristic algorithm was primarily based on the natural obligate brood parasitic behavior of some cuckoo species in combination with the Lévy flight behavior of some birds and fruit flies. Through the integration with the Roulette wheel selection operator and the inertia weight controlling the position (solution) exploration, the MCS-based weighted sum approach optimized concurrently the array element excitation locations, amplitudes, and phases within the uniform pattern and Dolph-Chebyshev window, respectively. The optimal solutions obtained were then compared against the conventional (with λ/2 inter-element distance) and other chosen evolutionary algorithms-based arrays.
Abstract.A dual-band bandstop microstrip filter is proposed and designed by using microstrip resonator with Defected Ground Structure (DGS). The DGS are placed in the ground plane to obtain high attenuation of the bandstop filter response. The proposed is designed by using R04003C printed circuit board with dimension of 38 mm x 20 mm. Simulated result shows an insertion loss of -12.31 dB, a return loss at -1.75 dB for center frequency at 2.4 GHz and insertion loss of -22.93 dB, a return loss of -0.78 dB for center frequency at 5.8 GHz The results of simulated in different parameters of DGS is analysed and discussed.
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