A.K. Shrivastav

Formulation of size reduction technique in microstrip circuits by using DGS and DMS

In this work a simplified and accurate mathematical formula is derived to predict the reduced dimension of the microstrip circuit by using applicable etching geometry on plane of microstrip circuit such as DGS/DMS that will affect the resonance frequency of microstrip circuit in desired direction due to increment of slow wave effect. Here we developed proportional formula of defect which is verified successfully by applying to network implemented with an open circuit and for microstrip patch antennas, phase shifter.

Wide band omni directional radiating array for cylindrical body

This paper describes a wide band patch array on a cylindrical body intended for omni directional coverage in the transverse plane of cylinder. The omni directional coverage is achieved by placing, the three antenna symmetrically apart on the circumference of the cylinder. Experimentally radiation pattern is measured and found that it meets the omni directional radiation requirement like aircraft and satellite application.

Design of C-Band 2-Stepped Septum Polarizer with Dual Matched Feed for Circular Polarization with Enhanced Gain

In this paper a two stepped septum polarizer is presented with matched feed using three pin to improve the gain and band width while polarization loss. This configuration shows about 10-15% bandwidth and it is therefore suitable for high sensitive, large bandwidth applications.

Designing of Varactor tuned microstrip patch antenna

A varactor tuned microstrip patch antenna has been designed and developed, with a view to predicting the obtainable tunable range. Tunability is achieved by connecting varactor diodes thus altering the capacitance of the patch and hence resonant frequency. Although this antenna has a narrow instantaneous bandwidth, electronic tuning allow a large band to covered whilst maintaining the same good narrow band operational characteristics. Evaluation of the antennapsilas performance is provided by practical results.

Designing of a compact microstrip antenna resonating at 4.8GHz by using size reduction technique

In this work a compact microstrip antenna has been design and developed. This antenna incorporated two symmetrical DMS like etching structure along length on patch surface of the antenna to minimize the size. Unlike normal antenna DGS/DMS introduces discontinuities on the signal plane which in turn disturbs shielded current distribution in signal plane. Due to which apparent permittivity of the substrate varies as a function of frequency and play important role in the performance of the antenna. A size reduction of 40% at 4.8GHz was observed. We also calculate all other parameters like apparent permittivity, phase velocity of wave, equivalent inductance and capacitance. Here we implement proportional formula of defect in three steps to get compact size of antenna which has higher impedance bandwidth w.r.t conventional patch antenna approximately 23.1MHz. For this work we care the overall performance like radiation pattern, efficiency, gain, directivity, polarization should not degraded by inserting slot. Here we also observe that performance of antenna is a function of shape, size, and position of DMS which is inserted. We use symmetrical DMS along length to avoid cross polarization. We not prefer here to use DGS because DGS also acts as radiating element which increases the back lobe radiation.

Application of FEM technique in realization of PIN Diode attenuator

FEM analysis has been used to optimize various microstrip line sections used for designing PIN-Diode π attenuator used for phased array antenna applications. Results have been compared with the theoretical results obtained from closed form analysis expressions of microstrip line. An error of only 0.92% has been observed between the two results at 50Ω characteristic impedance for unshielded microstrip line.