Jawad Y. Siddiqui

Compact SRR Loaded UWB Circular Monopole Antenna With Frequency Notch Characteristics

This paper presents the design of a compact split ring resonator (SRR) loaded coplanar waveguide (CPW) fed ultrawideband circular monopole antenna having frequency notch characteristics. The electromagnetic coupling of the SRR with the CPW yields the frequency notch. Fabricated prototypes were measured and compared with simulations and good agreement was obtained. The impedance and radiation plots confirm the suppression of the desired notch frequency. A theoretical formulation to calculate the notch frequency is also proposed and validated.

Concentric Ring-Shaped Defected Ground Structures for Microstrip Applications

A new defected ground structure (DGS) consisting of concentric circular rings in different configurations is experimentally studied to examine the stopband characteristics. Unlike previous DGS designs, a metallic shielding is introduced at the back of the DGS to suppress any leakage or radiation, and this would be advantageous for microwave circuit applications. A wide stopband is demonstrated with a set of prototypes designed for X-band. Its application to suppressing mutual coupling in microstrip patch arrays is demonstrated

Resonant frequency of circular microstrip antenna covered with dielectric superstrate

A simple design formulation to compute accurate resonant frequencies of circular microstrip antennas covered with dielectric superstrates is proposed. It alleviates the rigorous mathematical analyzes and large computational time of some earlier works. This theory is widely applicable to both high and low dielectric constant superstrates as verified with the experiments and other theoretical models. Of all theories, the present one shows the closest approximation with the measurements revealing average percent error as low as 0.52%. The extension of this formulation to predict the accurate design data for conventional microstrip circular antennas are also verified with different experiments and available improved theories for various sets of antenna parameters.

Resonant frequency of equilateral triangular microstrip antenna with and without air gap

A tunable equilateral triangular microstrip patch (ETMP) antenna with a variable air gap between the substrate and the ground plane has been studied theoretically and experimentally. Calculated resonant frequencies for different air gap heights have been verified with measurements of a coax-fed antenna. The tunability of the antenna as a function of the air gap height is studied theoretically showing over 200% tunable range of an ETMP with 50 mm side length printed on a substrate with /spl epsiv//sub r/=10.5. The computed results for the antennas with zero air gap height are compared with a standard spectral domain moment method analysis supported by other previously reported experiments. Very close agreement is revealed in all comparisons.

Compact Dual-SRR-Loaded UWB Monopole Antenna With Dual Frequency and Wideband Notch Characteristics

This letter presents the design of a compact dual-split-ring-resonator (SRR)-loaded coplanar waveguide (CPW)- fed ultrawideband circular monopole antenna exhibiting dual frequency notch and wideband notch characteristics. The SRR pairs are inductively coupled to the radiator and loaded on the back side of the CPW line. Fabricated prototypes were measured and compared to simulations, and good agreement was obtained.

Rectangular Microstrip Patch on a Composite Dielectric Substrate for High-Gain Wide-Beam Radiation Patterns

A rectangular microstrip patch on a composite substrate is theoretically and experimentally investigated. Considerably wide radiation beamwidth along with high gain is experimentally demonstrated. Compared to a conventional microstrip patch, the proposed configuration shows as much as 75% increment in beam width in its H-plane and nearly 10% in E-plane, indicating the peak gain of the order of 8 dBi.

Square split ring resonator backed coplanar waveguide for filter applications

In this paper, we present a design of a coplanar waveguide loaded with square split ring resonators for filter applications. A theoretical formulation to estimate the resonant frequency of the square split ring resonator is also proposed. Experimental verification of the proposed theory is reported and the computed data are also compared with

Simple design of a novel broadband antenna: inverted microstrip patch loaded with a capacitive post

Much effort has been devoted to developing broadband and multiple frequency microstrip antennas. A novel technique to enhance the bandwidth of an inverted microstrip antenna is proposed. A simple design using a circular patch loaded with a capacitive post is described. The bandwidth characteristics of the antenna have been critically examined on the basis of experiments with a prototype antenna fabricated on RT- Duroid 5880 and measured on an HP 8720C network analyzer. Over 21 % impedance bandwidth for SWR<2 is evident from the experimental data. Measured radiation patterns are also presented. The new antenna design with a capacitively loaded inverted microstrip patch shows the possibility of achieving very large impedance bandwidth with satisfactory radiation patterns.

Effect of a cavity enclosure on the resonant frequency of inverted microstrip circular patch antenna

The inverted microstrip circular patch (IMCP) antenna has been analyzed very recently by the present authors and the same microstrip structure enclosed in a cylindrical cavity has been employed by others to develop various active integrated antennas. In this paper, the effect of the cylindrical enclosure in changing the resonant frequency of an IMCP has been studied both theoretically and experimentally. The cavity-effect critically depends on the enclosed patch and the cavity dimensions which are thoroughly investigated to help a designer in choosing the antenna parameters. An efficient analytical formulation is also proposed to predict accurate resonant frequencies of the cavity enclosed IMCPs and is verified with different experimental data.

Effect of a Cylindrical Cavity on the Resonance of a Circular Microstrip Patch With Variable Air-Gap

The effect of a cylindrical cavity enclosure in shifting the resonant frequency of a suspended substrate circular microstrip patch with variable air-gap is investigated and an analytical formulation is proposed to accurately estimate the same. A new factor indicating the proximity effect of the cavity wall is also suggested and studied. The proposed formula is compared with some measurements and simulated data generated using Ansofts HFSS v9.2 revealing much closer agreement compared to a previously reported formulation