In this paper, we present an effective technique of second and third harmonic suppression for a Wilkinson power divider by using an asymmetric spiral defected ground structure (DGS). With the proposed technique, a single asymmetric DGS provides two different resonance frequencies because of the different sizes of spiral-shaped defects on the ground plane. The transfer function of the asymmetric DGS shows signal rejection characteristics at two different resonance frequencies and the characteristics of asymmetric DGS is modeled by two parallel RLC resonance circuits in cascade. With the insertion of asymmetric spiral DGS into a quarter-wave line of the Wilkinson power divider, the second and third harmonics are suppressed simultaneously. In experimental results, 18-dB suppression for the second harmonic and 15-dB suppression for the third harmonic, respectively, are achieved. Using asymmetric DGS, the size of a quarter-wave line is reduced by 9.1% compared to that of the conventional divider without a DGS.

Suppression of harmonics in Wilkinson power divider using dual-band rejection by asymmetric DGS

Novel slot-shaped defected ground structures (DGSs) on the microstrip line are presented to provide a band-rejection property with an improved Q factor. Two different geometries (U-slot and V-slot) are investigated. U-slot and V-slot DGSs have simple shapes compared to the conventional DGSs, however, they provide more steep rejection characteristics. The Q factor of the band-rejection property for the U-slot DGS increases when the distance between two slots in the U-shape decreases. Similarly, the V-slot DGS provides a higher Q characteristic when the slot angle is reduced. Two bandstop filters are designed and fabricated employing three cascaded U-slot DGSs and V-slot DGSs, respectively. Experimental result shows that the high-Q band-rejection filter with three U-slot DGSs provides Q of 38.6. A fabricated filter with three cascaded V-slot DGSs also rejects the signals at the frequencies from 3.5 to 4.3 GHz with more than 20-dB suppression

Novel U-slot and V-slot DGSs for bandstop filter with improved Q factor

A novel elliptic-function low-pass filter (LPF) is presented, which consists of a dumb-bell-shaped defected ground structure (DB-DGS), a spiral-shaped defected ground structure (SP-DGS) and a broadened microstrip line. The DB-DGS provides the required wideband attenuation in stopband, while the SP-DGS provides steep transition from passband to stopband. A 2.4 GHz five-pole LPF is developed and experimental results show that it has a sharp cutoff frequency response. The measured passband insertion-loss is below 0.3 dB, and the rejection band over 20 dB is from 2.95 to 8.25 GHz.

Compact Elliptic-Function Low-Pass Filter Using Defected Ground Structure

In this paper an edge coupled microstrip coupler with defected ground structure is presented. A normally 7 dB coupler designed on Alumina substrate is converted into a 3 dB coupler by cutting single rectangular slot in the ground plane encompassing the two transmission lines. Other properties of backward wave coupler remain the same, except for a tighter coupling. With this method of design optimization, it will be possible to fabricate a 3 dB coupler in compact form without strain in fabrication process. The structure is analyzed considering magnetic and electric coupling between the two transmission lines. Simulation based studies show reasonable agreement between analytical results and corresponding simulation results.

/pdf/design-of-a-novel-3db-microstrip-backward-wave-coupler-using-42wdd2qr6g.pdf

Design of a Novel 3db Microstrip Backward Wave Coupler Using Defected Ground Structure

In this paper, an E-shaped patterned ground microstrip bandstop resonant cell is proposed. In comparison to other bandstop resonators, it provides the advantages of a high-Q factor, and a sharp transition knee within a small circuit area. This resonant cell is applied to the design of a tunable bandstop resonator. Due to the unique E-shaped pattern etched in the ground plane, the proposed resonant cell is able to provide tuning function within a small circuit area.

/pdf/a-compact-e-shaped-patterned-ground-structure-and-its-4obrq7gau3.pdf

A Compact E-Shaped Patterned Ground Structure and Its Applications to Tunable Bandstop Resonator

We proposed the newly etched DGS (Defected Ground Structure) with a spiral shape in metallic ground plane and the equivalent circuit modeling applied to a spiral DGS for the microstrip line. The proposed spiral DGS can provide steep rejection characteristics with the one and only spiral. The equivalent circuit for the spiral DGS Is derived by means of three-dimensional field analysis methods. To represent spurious resonance, the equivalent circuit of a spiral DGS is consisted of an Inductor and a shorted stub with step impedance. The circuit parameters are extracted from a simple circuit analysis method. Experimental results show excellent agreements with circuit simulation results in wide band and the validity of our circuit modeling for the spiral DGS.

/pdf/the-equivalent-circuit-modeling-of-defected-ground-structure-5fjd29g4k0.pdf

Jong-Im Park

Papers

The equivalent circuit modeling of defected ground structure with spiral shape