In this work a compact planar butler matrix is presented by removing the 0 dB crossover. The proposed butler matrix consists of 45°and 90°phase shifter, and four branch line coupler miniaturised by employing open stubs in each transmission line. As the crossover is removed from the circuit, the circuit size is reduced and the performance is enhanced compared to the conventional Butler matrix. The response obtained from the newly designed butler matrix is comparable to the conventional butler matrix which is operated at 2.5 GHz. The size occupied by the proposed butler matrix is 2.01k g 9 1.13k g . A phase difference of ±45°and ±135°is obtained between the output ports with a maximum of differential phase tolerance of 3°and S-parameter magnitude with a leeway of ±1.5 dB from the theoretical results. As the phase tolerance is within the acceptable limit of bandwidth region, so the interference in beams is found negligible. The measured result and simulated result is in accord. The planar circuit of very low cost with good performance can be used to provide feed to an antenna array system.

No abstract

No abstract

No abstract

No abstract

A 10 dB branch line coupler with a dumbbell shaped defected ground structure (DGS) is proposed in this paper. The 150 ohm transmission line of the proposed BLC above the substrate is of much small size than the conventional due to the DGS in the ground layer. The equivalent LC circuit of the proposed 150 ohm line is obtained. The proposed 150 ohm transmission line is now used in the 10 dB branch line coupler. The proposed 10 dB coupler is now of reduced size and from the simulation result it's seen that flatness of the response increases, in turn increasing the bandwidth. Keywords-DGS, defected ground structure, 10 dB branch line coupler, branch line coupler, BLC.

No abstract

In these work, a cheap and compact Low-Pass filter (LPF) with wide stopband is designed using modified hairpin resonator. The first transmission zero is obtained from the transfer function (TF) analysis of the hairpin resonator. Further, open stubs are added to widen the stopband. An approximate LC equivalent circuit of the proposed structure is derived and the response is in accord with simulated result. A prototype of the proposed LPF is fabricated on FR4 substrate. The proposed LPF has-3 dB cutoff frequency at 1.1 GHz with wide stopband ranging from 1.6 GHz to 11.5 GHz. The size occupied by the proposed LPF is 15.8 mm x 14.3 mm. In the passband region, the insertion loss is-0.3 dB and return loss is better than-25 dB. The proposed LPF is measured and there is a good agreement between the simulated and measured results.