M. Ramesh

Design of a tri-section folded SIR filter

This letter reports the design of a suspended substrate stripline bandpass filter with relocatable second pass band using tri-section folded stepped impedance resonators (TFSIRs). Resonance conditions for the TFSIR in terms of impedance ratios have been derived. Location of the second pass band as a function of impedance ratios (of TFSIRs) has been studied in detail. Experimental results of a filter designed at 2.95 GHz with 31% bandwidth have been compared against the simulation results.

Design of optimized CPW fed monopole antenna for UWB applications

Optimized design of a CPW fed monopole antenna with tapered ground plane suitable for UWB applications is presented through extensive parametric studies. Techniques to improve the impedance bandwidth of this antenna are given. Experimental results of the antenna designed using the present optimization procedure have been compared against the simulation results.

A Compact Branch Line Coupler Using Defected Ground Structure

This paper reports the design of a compact branch line coupler based on defected ground structure (DGS) in microstrip medium. Unit cells (of DGS) equivalent circuit has been used to evaluate the performance of coupler. Based on this approach, a compact coupler has been realized at 2.4 GHz yielding a size reduction of 33% over the conventional coupler.

Design method for patch antennas short circuited at one end

This paper presents design equations, analysis and empirical formula for locating the coaxial feed point for a 50 /spl Omega/ input impedance of a thin rectangular patch antenna short circuited at one end. The experimental results of a trapezoidal patch antenna short circuited at one end is also presented. Since there is a reduction in size and an increase in bandwidth, these antennas find applications in pagers and handsets.

Dual band(WLAN & WiMAX) suppressed harmonic microstrip filter with perturbed ground

Design of a dual band pass filter employing microstrip line with defected ground is presented in this paper. A dual band filter at 2.45GHz and 3.5GHz (covering WLAN and WiMAX) with 6% bandwidth has been designed at each frequency. Apertures in ground plane were used to improve the stop band rejection characteristics and coupling levels in the filter. Measured results of the experimental filter were compared against the simulation results for the purpose of validation.

Broad Band Filter for UWB Communications

Design of a broadband filter using broad side coupled line sections in suspended substrate stripline (SSS) medium, suitable for ultra wideband (UWB) applications has been reported in this paper. Broad side coupled line parameters and ground plane spacing have been appropriately chosen to locate the two attenuation poles close to either side of the desired pass band. Effect of ground plane spacing on the filters bandwidth has also been studied. Experimental results of a UWB filter designed using the present technique have been verified against the simulation results

Miniaturized Defected Ground High Isolation Crossovers

This letter relates to the design of crossovers for carrying criss crossing signals. Two types of crossovers are proposed in this letter. Both the crossovers are designed using a two layer printed circuit board. An unbroken continuous transmission line is routed in the top layer for carrying signal 1 from one node to another node. Transmission line used for carrying a signal 2 consists of three physically discontinuous, but electrically connected segments. Two end segments of these are located in the top layer while the middle segment is placed in the bottom layer. While Type I crossover offers an isolation of 25 dB, Type II crossover offers isolation better than 35 dB from dc to 10 GHz. These crossovers are compact and measure an actual size of 10×10×0.78 mm3.

Analysis of multi-conductor coupled microstrip lines with an aperture in the ground plane for the design of a broadband filter

Closed-form expressions for the propagation characteristics of coupled microstrip lines with a symmetrical aperture in the ground plane are derived. Expressions for the regular microstrip coupled lines have been modified using physical insights to incorporate the effect of the aperture. The accuracy of these expressions has been verified by full-wave simulations and compared with conformal mapping analysis. These expressions are accurate within 5% for a substrate whose thickness varies from 0.2 to 1.6 mm and permittivity in the range of 2–10. Designing a broadband filter based on planar multi-conductor coupled lines with aperture in the ground plane is demonstrated in this paper using the proposed expressions for its practical use.

A compact two layer broadside coupled UWB filter

Design of a compact ultra wide band filter over 3.1GHz to 10.6GHz using broadside coupled lines and folded open circuit stubs in microstrip medium has been presented in this paper. Desired broad band operation is achieved using broadside coupling between feed lines and an embedded floating conductor in the ground plane of a microstrip. Folded open circuit stubs have been incorporated to improve the stop band rejection characteristics of the filter. Filter has been analyzed based on circuit models and full wave simulations. Experimental results of the proposed ultra wide band filter have been verified against the results obtained from circuit models and full wave simulations. Results are in close agreement with each other. The filter measures an overall size of 22×10×0.787mm3.

Parametric studies on isolation in probe-fed dual polarized microstrip antennas

Dual polarized antennas are useful for both polarization diversity and frequency reuse applications. Isolation between the ports is a critical parameter and need to be considered in the design of dual polarized antennas. Parametric studies using IE3D have been presented to observe the relationship between height of layers and isolation. This paper also presents variation of isolation with spacing between the two probes for both single and stacked patch antennas. Guidelines for designing dual polarized antennas are provided