Somdotta Roy Choudhury

Design and improvement of bandwidth of a compact and wide band rejection filter

A novel bandstop filter (BSF) structure is proposed for wideband and compact circuit applications. First of all the parametric study of the single unit is done. The bandwidth is improved by cascading the unit sections with non-uniform dimensions and periods. This proposed filter is suitable for percentage bandwidth of 44 %. This filter is a very much compact as compared to the shunt-stub and coupled-line bandstop filters since the structure is limited in 50 ohm microstrip line width.

Design of a novel bandstop filter using log periodic based circular split ring slots

Compact planar microstrip bandstop filters are introduced here. These filters consist of log-periodic based 3 resonator elements. These defects or slots on the signal plane effecting resonant frequency of the filters due to increment of slow wave factor, which exhibits good bandstop characteristics. The filters can be designed to function in a low frequency to a very high frequency range depending upon the physical dimension of the slots. When the filters are designed at lower frequency, the guided wavelength is increased by increasing the radius of the split ring slots and vice versa. First of all a unit cell is investigated. A set of circular split ring slots are designed to achieve stopband of the filter at desired frequency range.

Ultra-wideband coplanar waveguide-fed hexagonal slot antennas with WLAN band rejection

In this paper, printed regular hexagonal slot antenna fed by a coplanar wave guide line has been presented for ultra wide bandwidth. The hexagonal shape stub is used. The antenna is then modified to possess band rejection at the wireless local area network (WLAN) (5.1–5.8 GHz) by a C-shape slot within the exciting stub. The length and width of the C-shape slot offer sufficient freedom for selecting and shifting the notched band. VSWR, impedance, gain and radiation characteristics are presented and discussed. From the results, it has been observed that, the impedance bandwidth, defined by 2≤VSWR, can reach a value of 6.5GHz (3.1∼9.6GHz), while stop bands of 5.15 to 5.8 GHz. The proposed antenna gain varies 4 dB to 5.3 dB over the whole operating band excluding the notch band. Surface current distributions and transmission line model are used to analyze the effect of the slot.

Compact stop band filter based on double tuned rectangular split ring defected microstrip structure for ISM band applications

A novel compact stop band filter consisting of a rectangular split ring resonator (SRR) etched on the 50 ohm microstrip transmission line is presented in this paper for designing a sharp band rejection filter. Compared to the conventional defected slots like DGS, EBG etc., the proposed rectangular split ring shaped slot has a simple shape but compact in size as it occupies only the width of 50 Ω microstrip line. Another smaller rectangular split ring slot is attached inside the previous split ring slot to obtain a sharp double pole stopband response. Experimental results show that the proposed band stop filter with two rectangular split ring slots having a good agreement with theoretical simulation results. This double resonant bandstop filter can be tuned to reject the frequencies at 2.45GHz and 5.8GHz, which are applicable for ISM bands. This is useful to reject the notch band at 2.45 GHz and 5.8 GHz of an ultra wideband bandpass filter.

Realization of ultra wideband bandpass filter using new type of split-ring Defected Ground Structure

This paper introduces a new compact bandpass filter using a new Circular Split — Ring type Defected Ground Structures. A split ring Defected Ground Structure (DGS) when applied with a continuous microstrip line yields a very sharp stop band Lowpass filter. In the proposed structure, a T-shaped discontinuous microstrip line is included, which provides ultra wide passband. The passband of the proposed bandpass filter can be tuned by simply changing the radius of the inner ring of the split-ring DGS unit. This proposed structure provides an improved bandwidth when another split-ring DGS unit is included. A MoM based simulation is performed for the structures.

Design of circular split-ring type Defected Ground Structure as elliptic filters

A Defected Ground Structure in the metallic ground plane of a microstrip line is attractive solution for achieving finite pass band, rejection band and slow-wave characteristics. A split-ring shaped DGS structure has a high selectivity would be preferable owing to the demand for currently expanding communication systems within finite spectrum resources. First of all a split-ring type DGS unit slot is designed underneath a pair of T-shaped microstrip line. [1–4]. Thus just applying a T section at the upper plane of DGS unit a lowpass filter can be changed to a sharp response highpass filters