Sunil Kumar Khah

Numerical Computation of Resonant Frequency of Gap Coupled Circular Microstrip Antennas

In this paper the numerical computation of resonant frequency of gap coupled circular microstrip antennas using the concept of cavity model has been presented. The resonant frequency of the gap-coupled circular patches is computed and the mode number is also evaluated. The computed results are compared with published results. The previously published results are based on experimentation and do not present a clear mathematical model for the same structure. An extensive comparison with Method-of-moments based software (IE3D) is also done. The accuracy of prediction is reasonably good.

EXTENDED CAVITY MODEL ANALYSIS OF STACKED CIRCULAR DISC

Stacked microstrip antennas deserve special attention due to their advantageous properties like dual frequency operation and wide bandwidth. In the present communication a theoretical model for single stacked microstrip disc antenna is proposed using extended cavity model. The method of analysis by this model is easier and intuitive than the full wave analysis. Single stacked microstrip disc antenna with co-axial feed locations at different radial positions is analyzed with this model taking different ratios of patch sizes. Antenna properties like return loss, input impedance, gain and radiation efficiency are calculated with the proposed model different cases and compared with the simulated and experimental results. The results are in fairly good agreement.

Wideband DGS Circular Ring Microstrip Antenna Design Using Fuzzy Approach with Suppressed Cross-Polar Radiations

This paper presents a novel design of a circular ring defected ground structure (DGS) antenna for bandwidth enhancement using fuzzy logic approach. The ground plane of the antenna is defected by introducing circular ring sector type of defect beneath the circular ring patch. The position of the defect in the ground plane to attain the highest return loss and corresponding frequency is determined by using Fuzzy Inference System (FIS). The antenna resonates in X-band showing wideband characteristics with improved gain and reduced cross polar components. The return loss and analogous frequency obtained from simulated results and fuzzy system are compared and are in good agreement. The return loss and input impedance is measured experimentally and compared with the simulated results. Parameters like impedance bandwidth, VSWR and antenna gain are likewise calculated and discussed. The simulated results for the radiation pattern of the proposed design with polarization (Co-polar and Cross- polar) are also presented. The simulated impedance bandwidth of about 1.33GHz (1.2GHz experimentally) in X-band is obtained with a gain of 6.43dB and also cross-polarized radiations have an isolation of 20dB.

A Novel Design of Gap-Coupled Sectoral Patch Antenna

Using gap coupling between the elements, an antenna of four sectors by cutting the slots through and through from a circular patch is designed for application in X-band. The bandwidth enhancement along with reduced sidelobes is obtained by marginally or fully moving one of the feeding sectoral patches diagonally away. The results are analyzed for different positions of the slot. A bandwidth of 1.2 GHz in X-band along with a reduced sidelobe level of -15.0 dB and a gain of 12.0 dBi is obtained. An analysis of mutual coupling and parasitic patch effect is also presented and discussed in this letter.

Improved characteristics of DGS ring antenna in L-band

A compact design of defected ground antenna working in L-band is proposed in this communication. The antenna resonates in the frequency range between 1–2 GHz. The parameters such as return loss, input impedance, antenna gain and side lobe level are thus presented and discussed. A comparison is also shown for the proposed antenna with the antenna structure without defect. A very good return loss of −32 dB with a gain of 6.6 dBi is obtained for the defected ground structure (DGS) ring antenna.

Analysis of an Electromagnetically Coupled Microstrip Ring Antenna Using an Extended Feedline

A new method for the computation of input impedance of an annular ring microstrip antenna, fed electromagnetically by a microstrip line, and operating in its fundamental mode is presented. The method based on cavity model in conjunction with circuit theory is compared with simulation (IE3D™) and measurement based results. It is shown that this method of computation leads to accurate prediction of impedance for such structures with minimum of computational complexity, thereby making it an attractive tool for accurate and quick design estimate for many applications.

A new, compact, efficient, parasitically coupled notch-loaded antenna

This paper presents a new, compact, efficient, wideband and low side-level parasitically coupled notch-loaded antenna array for communication systems. The antenna structure consists of a circular microstrip antenna coupled parasitically with notch-loaded rings. The proposed antenna is also considered using different dielectric substrates and the results are compared. The simulated results are compared with the experimental results and are found to be in good agreement with each other.

Study of bandwidth and radiation properties of loaded annular ring antenna

Loading of microstrip antennas provides dual frequency, tenability and compactness. In this paper a theoretical method is developed to calculate various parameters of loaded annular ring antenna via. Shorting pins. The pins are located symmetrically i.e. equispaced along the circumference of the annular ring. Various parameters such as input impedance, bandwidth, return loss, quality factor and radiation properties are calculated. The theoretical results results are in good agreement. TM01 is the dominant mode of propagation for the loaded annular ring antenna. The radiation properties are more directional when the antenna is loaded and the bandwidth is also enhanced.

Extended Cavity Model for Input Impedance of Annular Microstrip Antenna Loaded with Multiple Shorting Posts

A new method for impedance of an annular patch loaded by multiple posts is presented using extended cavity model. The post is loaded away from the centre of the ring. The input impedance for dominant mode is calculated with this method and compared with the measured and simulated results. For the simulation IE3D software is used based on method of moment.

Wideband Gap Coupled Sectoral Antenna for Communication Systems

This paper presents the design of a novel wideband gap coupled sectoral antenna for communication systems. The circular patch is placed in the aperture of four sectoral rings. The antenna parameters are optimized using various simulations to attain good return loss and corresponding resonant frequency. The antenna operates in X-band at 10.35GHz showing wideband characteristics along with high directivity and reduced side lobe level to a good extent. The antenna has also been studied using fuzzy inference system (FIS). The return loss and analogous frequency obtained from simulated results and fuzzy system are compared and in good agreement. Design is extended to an array of nine elements mutually coupled to the active fed patch. The antenna is fabricated, and the simulated results are found to be in good agreement with experimentally measured ones. A bandwidth of 900MHz at resonant frequency of 10.35GHz with a directivity of 7.0 dBi and reduced side lobe level of −18.9 dB is therefore obtained.