Z. Baharudin

Parametric effect of defected ground structure (DGS) on frequency of a bandpass filter

A stepped impedance resonator bandpass filter (SIR BPF) is proposed and designed by placing defected ground structure (DGS) in the ground plane. DGS is used for its property of miniaturizing the size of microwave filter and also improving the mutual coupling between the resonators. The proposed dumbbell shaped DGS is used to tune the bandpass filter to 2.4 GHz with dimension of 28 mm × 30 mm. A wide tuning range of 0.64 GHz is achieved by tuning the height, length and width dimension of DGS unit cell. This filter gives an insertion loss of -0.23 dB, a return loss of -38.03 dB and -3 dB bandwidth of 0.56 GHz. The tuning of SIR bandpass filter, using DGS structure parameters is discussed here. Moreover, the effect of different parameters of DGS on center frequency is shown and discussed with results.

Tuning of end-coupled line bandpass filter for 2.4 GHz using defected ground structure (DGS) parameters

Defected ground structures (DGS) have known to be serving for the improvement in characteristics of many microwave circuits. Not only DGS has various advantages in the area of microwave power amplifier, Wilkinson power divider, microwave antennas, couplers etc, it is also used in the design of microwave filter to achieve stopband effects, slow-wave effects, frequency adjustment etc. A bandpass filter based on Dumbbell-shaped DGS unit is presented here. This unit provides two transmission zeros near the passband edges. The center frequency has been tuned to 2.4 GHz using different dimensions of DGS. This filter gives an insertion loss of -0.42 dB, a return loss of -12.31 dB and -3 dB bandwidth of 0.92 GHz. The tuning of end-coupled line bandpass filter, using dumbbell DGS structure parameters is discussed here. The measurements show a close agreement with simulation results.

Microwave bandpass filter using QMSIW

A planar bandpass filter based on a technique that utilizes quarter mode of substrate integrated waveguide (SIW) is presented. This concept reduces the circuit foot print of SIW to a quarter of its size, along with miniaturization good performance and high quality factor is maintained by the structure. The design concept for single-pole resonator structure is presented; and by coupling the resonators a two-pole substrate integrated waveguide bandpass filter is achieved for the frequency of 5.9 GHz. The results show that the filter insertion losses are better than 2 dB and return losses are less than 20 dB. The measured frequency response is in good agreement with the simulated response in the region of interest.

Recent advances in miniaturization of Substrate integrated waveguide bandpass filters and its applications in tunable filters

The concept of Substrate integrated waveguide (SIW) has emerged to be a good replacement of rectangular waveguides in low-cost and high-volume microwave and millimeter wave band applications. A number of bandpass filters have been developed since the advent of the SIW technology. However, its various forms have also been introduced in order to bring about further reduction in the footprint of these filters. This paper presents a review on the technological implementation of Substrate integrated waveguide bandpass filters and its variant miniaturization techniques developed so far. It also covers the SIW technology applied in tunable filters.

Aperture coupled Cylindrical Dielectric Resonator Antenna design with box shaped reflector

A single element circular slot aperture coupled Cylindrical Dielectric Resonator Antenna (CDRA) with a box shaped reflector is designed and presented. The simulated bandwidth achieved for the designed antenna is about 1.11% (5.32 GHz-5.44 GHz) while the measured bandwidth is about 1.8% (5.32 GHz-5.52 GHz). This method enhances the directivity of the CDRA upto 53% i.e from 5 dBi to 7.5 dBi. The analysis of the effects of changing the slot size, slot position and different parameters of the reflector to increase the directivity and to reduce the backlobe level has been carried out. The experimental results illustrate that the designed antenna works over 5 GHz band, therefore it can be used in WLAN application IEEE 802.11a.

2.45 GHz cylindrical dielectric resonator antenna fed by dielectric image line

In this paper, the experimental study on cylindrical dielectric resonator antenna (CDRA) with an aperture coupled dielectric image line (DIL) is presented using a CCTO material. The CDRA is fed by a 50Ω dielectric image line at a frequency around 2.45 GHz. High permittivity (εr = 55) DIL samples with different heights are employed. The CST microwave studio is used to analyze the different results in term of return loss, bandwidth and radiation pattern. The DIL feeding technique has shown a better directivity for CDRA as compared to microstrip line coupling.

Aperture coupled Dielectric Resonator Antenna design with flat reflector

A single element circular slot aperture coupled Cylindrical Dielectric Resonator Antenna (CDRA) with a flat reflector is designed and presented. The measured bandwidth of the antenna is about 1.8 % (5.32 - 5.52) while the simulated bandwidth is 1.11% (5.32 - 5.44 GHz). A comprehensive parametric study has been conducted to realize the effects of slot size, slot position and reflector parameters to increase the directivity of the designed antenna. The experimental results show that the antenna covers 5 GHz band, which satisfies the basic requirement of the WLAN application IEEE 802.11a.

Cylindrical dielectric resonator antenna with TE 011 + δ mode

In this paper, theoretical and experimental study on cylindrical dielectric resonator antenna (CDRA) made of CCTO material is reported. The CDRA with high dielectric constant (εΓ = 55) is fed with aperture coupled 50 ς microstrip transmission line. The TE011+S mode of CDRA is excited to operate at 5.15-5.35 GHz for wireless local area network (WLAN) application. The electrical model of the aperture coupled CDRA is built to verify the antenna feasibility. The validity of the electrical model is confirmed by comparing the values of the return losses obtained through an electrical model using Agilent Advanced Design System (ADS) against those obtained through antenna geometry using computer simulation technology (CST) and fabricated prototype.

Electrical model of two element aperture coupled cylindrical dielectric resonator antenna array

In this paper, electrical models of single element cylindrical dielectric resonator antenna (CDRA) and two element CDRA array made of Calcium Copper Titanium Oxide (CCTO) material are presented. The 50 Δ microstrip transmission line is used to excite the CDRAs through coupling slots etched on the ground plane. The electric models of single element CDRA and two element CDRA array are designed by using Advanced Design System (ADS). The electrical circuits are used to validate the CST design feasibility. The validity of RLC model is verified by comparing the return loss of the ADS model against those obtained through computer simulation technology (CST) and fabricated prototype. The results obtained through simulated (CST and ADS) designs and fabricated prototype of single element CDRA (0.20 GHz and 0.23 GHz) and two elements CDRA array (0.375 GHz and 0.510 GHz) are in good agreement.

Dual band aperture coupled cylindrical dielectric resonator antenna array

In this paper, the tuning technique of 3-elements cylindrical dielectric resonator antenna (CDRA) array for wireless LAN 802.11 a/b/g standard applications is studied experimentally. The rectangular shaped aperture slots are used to excite the first and last radiating element. The aperture slots etched on the ground plane are excited by using the 50Ω microstrip transmission line. The electromagnetic coupling technique is used to excite the middle radiating element to enhance the antenna bandwidth as well as gain. The effects of changing the dimensions of slot width on the resonance frequency are also analyzed using a CST microwave studio. The simulated and measured results have successfully given the resonance at 2.45 and 5.0 GHz. The 2-D and 3-D radiation patterns of the proposed dual band antenna are addressed in this paper.