Priyansha Bhowmik

Dual band multilayer E-shape microstrip patch antenna for C-band and X-band

The modern microwave communication system demands good antenna performance with variety of application. One antenna should serve the purpose of many antennas to reduce the resource cost and installation cost. For this reason the concept of multiband antenna arises. In this paper the attention has been given towards the design of a dual band antenna. In this paper a modified E-shaped compact size probe-feed microstrip antenna is proposed for dual band operation in C-band and X-band with increased bandwidth. The return loss, VSWR and gain is also improved in this antenna design compare to previous work on dual band design. HFSS 13.0 is used for simulation and analysis purpose. Though the proposed design is about dual band operation but the simulated result shows two resonant frequencies of 4.8 GHz and 6 GHz in C-band and 9.2 GHz in X-band which is an another advantage compare to previous work. The performance of this multilayer E-shape antenna is depends on the E-shape of the conducting patch, location and dimension of the layers and location and dimension of the probe feed. The operating frequency of the antenna is 4 GHz. An increased gain of 7 dB is achieved in this antenna.

Return loss and bandwidth enhancement of microstrip antenna using Defected Ground Structure (DGS)

In this paper a modified inset-feed microstrip antenna is proposed to increase band width and return loss. The operating frequency of the antenna is 2.4 GHz ISM band. To enhance the performance of the antenna one DGS has been introduced under the patch area that is on the other side of substrate and little modification in the dimension of feed gap. The DGS has been optimized to provide a stop band at 2.4GHz. The stop band of the DGS added with stop band of the inset-feed rectangular antenna which is responsible for enhancement of return loss. The DGS on the ground plane increases fringing field which introduces parasitic capacitance. This parasitic capacitance increases the coupling between the conducting patch and the ground plane which is responsible for the enhancement of the bandwidth. The performance of the antenna is depends on the physical dimension of the antenna as well as location and shape of the DGS. Zealand IE3D is used for simulation and analysis of the proposed antenna.

Size miniaturization of 3 dB branch line coupler by using open stubs

In this paper a miniaturized 3 dB branch line coupler (BLC) is proposed. The miniaturization is done by adding open stub to the series and parallel transmission line of the conventional 3 dB coupler such that the proposed T-shaped structure is equivalent to the conventional 3 dB branch line coupler. The equivalent circuit is obtained by comparing the ABCD parameters of the T-shaped and conventional transmission line. As the area is less there is a possibility of coupling between the stubs of series and parallel transmission line. Based on the flexibility of the designer the structure is designed in a way to minimal the effect of coupling between the stubs of the series and parallel transmission lines. The proposed structure has reduced size than the conventional coupler and has fair response at 2.5 GHz.

Compact Rat-Race Coupler-Based Microstrip Balun Without Any Isolation Port

In this work, a compact miniaturized microstrip balun is proposed by removing the isolation port of a Rat-Race Coupler (RRC). The proposed balun consists of six quarter-wavelength Transmission Line (TL), and the TL is designed using interdigital capacitor and high impedance TL in parallel configuration. The fractional bandwidth (FBW) of RRC and balun are 37.5% and 33%, respectively, at centre frequency 2.4 GHz for amplitude imbalance of ±1 dB and phase imbalance of ±8°. The size occupied by the proposed balun is 0.51 λg × 0.22 λg.

Coplanar Waveguide UWB Bandpass Filter Using Defected Ground Structure and Interdigital Capacitor

In this present work, a coplanar waveguide (CPW) ultra-wideband (UWB) bandpass filter (BPF) is proposed using defected ground structure (DGS) and interdigital capacitor having the exact passband frequency range of (3.1–10.6) GHz, minimum passband insertion loss of 0.14 dB and stopband rejection level below 20 dB from 11.8 to 16 GHz. Lumped equivalent circuit model of CPW UWB BPF is also extracted. Mathematical modelling to calculate values of generated inductances, capacitances and resistance of proposed BPF is indicated. Circuit size is miniaturized to an area of 7 mm × 9.3 mm and BPF is simulated on Fr4 substrate with dielectric constant of 4.4 and thickness of 1.6 mm. The proposed BPF is applicable for Bluetooth and wireless devices.

A low-cost 4.9 GHz balanced bandpass filter with good common mode isolation

Abstract This paper presents a compact and low-cost balanced bandpass filter (BPF) operating at 4.9 GHz with high selectivity using mixed coupled ‘U’ shaped resonators, parallel coupled feed line, open and centrally loaded short circuited stubs, respectively. The odd–even mode decoupling scheme and the weakly coupled resonator concepts are utilized for the analysis and validation of differential mode (DM) and common mode (CM) equivalent circuits of the proposed BPF. The passband CM response of the balanced BPF is suppressed above 30 dB by employing grounded stubs in the symmetry plane, which converts the CM response to an all stop characteristic. The second harmonics generated by the BPF is also suppressed using open stubs located near the feed lines. The proposed balanced BPF is fabricated on an FR4 substrate (εr = 4.4, h = 1.6 mm, tan δ = 0.02), which provides 10.7% measured 3 dB fractional bandwidth (FBW) and minimum 1.2 dB insertion loss in the passband (4.7–5.2 GHz). A good agreement is found between the simulated and measured results.

Design of a compact planar dual-band rat-race coupler using improved microwave C-Section

ABSTRACT This work presents a compact planar dual-band rat-race coupler (RRC) using improved microwave C-section. The difference in even- and odd-mode phase velocity is compensated by using wiggly lines in the structure. The wiggle depth is tuned to obtain a characteristic impedance of 70.7 Ohm and phase of 90° at 2.1 GHz and 5.3 GHz. The size of the proposed structure is 0.42 λg × 0.26 λg. The measured and simulated responses are in good agreement. The 1 dB bandwidth of the first and second bands is 670 MHz and 210 MHz, respectively, covering the GSM and WLAN bands. The structure is compact, simple, single layer, and cheap.

Design of a cheap compact low-pass filter with wide stopband

In these work, a cheap and compact Low-Pass filter (LPF) with wide stopband is designed using modified hair-pin resonator. The first transmission zero is obtained from the transfer function (TF) analysis of the hair-pin 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 cut-off 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.

Miniaturization and bandwidth enhancement of a loose coupler by DGS

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 its seen that flatness of the response increases, in turn increasing the bandwidth.