Noorlindawaty Md. Jizat

MINIATURIZED SIZE BRANCH LINE COUPLER USING OPEN STUBS WITH HIGH-LOW IMPEDANCES

In this paper, a miniaturized branch-line coupler is proposed. The topology of the circuit is designed using novel design of T-model approach with open stubs with high-low impedances, which provides necessary bandwidth for WLAN band at 2.45 GHz. The miniaturized branch-line coupler is designed and fabricated with a low-cost FR4 substrate as a platform in producing significantly reduction by more than 64.21% compared to the conventional coupler on inexpensive board. Furthermore, the coupler can equally divide the input signal with 90° phase of difference while maintaining the initial power from the source.

Dual Band Beamforming Network Integrated with Array Antenna

This paper presents dual band 4 ×4 Butler Matrix beam forming network integrated with antenna array operating at WLAN systems, 2.45GHz and 5.8GHz bands. Array antenna connected to a beam forming network can produce the desired multilobe radiation pattern. A signal fed in one port of Butler Matrix is divided into equal parts thus generate certain phase and equal amplitude which determine the beam direction. As a result, four orthogonal beams at -45°, -15°, 15° and 45° with high gain are produced. With the need for multi-functional and small-sized mobile telecommunication terminal devices, dual band terminals are widely spread, which are characterized by the simultaneous service of two or more frequencies in one device. In response to such demand, enhancement method of dual band beam forming network has been developed.

3-dB Branch-line coupler using coupled line radial stub with no restriction on coupling power

Investigation on the design of coupled line radial stub towards 3-dB branch-line coupler (BLC) operating for fourth generation (4G) Long Term Evolution (LTE) at 3.5 GHz has been presented in this paper. The investigation involves different parameter value of the radius of radial stub and coupled line length at the series and shunt arm of 3-dB BLC designs specifically without restriction on the coupling power performance. The designed BLC was simulated using Rogers RO4003C substrate with thickness of 0.508 mm and dielectric constant of 3.38. The results for proposed radial stub BLC were being compared in terms of S-parameter and phase difference. The comparison shows that 3-dB BLC with radial shaped stub optimized to 79% reduction compared to conventional design without having to compromise the performance result especially with no restriction on the coupling power.

Exploitation of the electromagnetic band gap (EBG) in 3-dB multi-layer branch-line coupler

An advanced shift that driven with high carrier frequencies, wide bandwidths, device densities, unique numbers, universal high-rate coverage and a seamless user experience present future 5G air interface and spectrum together with LTE is currently experiencing an explosive growth in the communication world. This letter presents performance improvement of multi-layer slot coupled 3 dB Branch-Line Coupler (BLC) with the integration of electromagnetic band gap into the design. The proposed BLC is simulated on a Rogers RT/duroid 5880 with permittivity of 3.38 and designed to operate at 7 GHz. A configuration of uniplanar compact electromagnetic band-gap (UC-EBG) structures is exploited to serve as a slot coupled ground to reduce mutual coupling between the radiating elements and to achieve a higher operating resonance frequency. The periodic structure of electromagnetic band gap (EBG) is considered in RF-microwave industry due to their extraordinary surface wave suppression property. The proposed BLC delivered simulated coupling and transmission values of 3.12 and 4.04 dB, respectively. The impedance bandwidths (BW) of the BLC significantly increase to 120% when integrated with an EBG slot coupled ground plane. The proposed BLC design was accomplished in multilayer microstrip-slot technology by employing coupling technique. Ultimately, these applications produce wide operational bandwidth in which the BLC will serves as an essential key beam forming network element for future 5G wireless communications.