Tamasi Moyra

Design of 10 dB branch line coupler by using DGS

A new planar 10 dB loose branch line coupler is proposed for application to the 2.5 GHz centre frequency. This proposed coupler is implemented with rectangular ring headed dumbbell shaped Defect Ground Structure (DGS) along with conventional microstrip transmission line. Design of this conventional branch line coupler with DGS provides more design flexibility. Using the DGS, increases the electrical length of microstrip line, provides slow wave characteristics and increases the impedance of the microstrip line. In this paper one required high impedance microstrip line is implemented easily using proposed DGS structure. Finally, the compact microstrip 10 dB loose coupler is designed.

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.

Microstrip Hairpin Bandpass Filter with Improved Out of Band Performance

This paper presents an microstrip bandpass filter using folded hairpin resonators with improved out of band performance. The 5 pole hairpin filter has a centre frequency of 2 GHz with a Fractional Bandwidth (FBW) of 0.2. The filter performance has been improved using a combination of Defected Ground Structure (DGS) and Defected Microstrip Structure (DMS) in the feed line to remove the spurious passband extending from 3.1 to 4 GHz. The combination of DGS and DMS provides a relatively wide stopband and at the same time has a steep rising and falling edge skirts so as to minimize the distortion in the actual passband. The structure has been designed using RT/Duroid 6006 substrate with a height 1.27 mm and dielectric constant 6.15. The proposed structure has been simulated by Method of Moment (MoM) based IE3D electromagnetic simulator. Finally, the filter exhibits a good bandpass response suitable for use in modern microwave and millimeter wave communication.

Design and performance improvement of lowpass filter by using Defected Microstrip Structure

In this paper, an elliptic-function lumped element lowpass filter is proposed and designed. The proposed LPF provides cut-off frequency at 1GHz and attenuation pole at 1.06 GHz with good sharpness factor and negligible passband insertion loss. Finally, the attenuation bandwidth is improved by the removal of spurious transmission peak which is occurs at about 3.2 GHz using 50 ohm microstrip line with spiral-Shape Defected Microstrip Structure (DMS). The designed filter is useable in modern microwave and millimeter wave communication systems.

Modeling and Validation of Coplanar Waveguide Elliptic Filter Using Square Open Complementary Split-Ring Resonator

Abstract In this article, an elliptic low-pass filter is implemented in coplanar waveguide technology by etching an open complementary split-ring resonator and one open split-ring slot in the central transmission strip. The structures behave as series-connected parallel resonant tanks, whereas metallic patches etched in the back side of the substrate provide the required shunt capacitances to achieve the elliptic function response. An order-5 elliptic low-pass filter has been designed to illustrate the possibilities of this new approach. Since the open complementary split-ring resonator is an electrically small resonator and the dimension of the open split-ring slot is also very small, the designed filter dimensions are also small compared to the filters designed by split-ring resonators, complementary split-ring resonators, or other procedures.

Parasitic effect compensation of defected ground structure and its application to design of bandpass filter

Abstract This study demonstrates the parasitic effect observed in the passband of a bandpass filter (BPF) using a defected ground structure (DGS). This parasitic effect has been compensated by employing step discontinuity in the microstrip feed line. By implementing this technique, the performance of a pseudocombline BPF of 5 GHz operating frequency and a fractional bandwidth of around 15% together with a DGS cell is improved. The filter provides less than −1 dB insertion loss in the operating frequency and a stop band attenuation of about −20 dB on average. When the final BPF structure is simulated, fabricated, and measured, good agreement is observed between the simulated and measured results. The BPF proposed is applicable in the wireless LAN and RADAR systems.

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.

Design of coplanar-waveguide-based elliptic filter using T-shaped defected ground structure

In this paper T-shaped Defected Ground Structure (DGS) has been proposed in the ground plane of the conventional coplanar-waveguide (CPW) structure. The T-shaped DGS has wider gap capacitance than the conventional dumbbell-shaped DGS, and provides a wide stop band and slow-wave characteristics. Thus, utilizing the above properties array of two T-shaped DGS structures has been introduced to obtain an elliptic low-pass filter (LPF). This proposed LPF is suitable for transferring low frequency signal up to 2.5 GHz satisfactorily. It provides sharp transition between pass- and stop-band with good sharpness factor, but almost 1.2 dB insertion loss in the pass-band. Therefore, the insertion loss in the pass-band is reduced with the help of compensated Hi–Lo coplanar waveguide (CPW) transmission line.

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.