Gap-coupled Configuration Research Articles

Design of wireless contact-lens antenna for intraocular pressure monitoring

Intraocular pressure is an important aspect in the evaluation of patients at risk from glaucoma. Glaucoma is an ocular disorder that results in the damage of optic nerve, often associated with increased aqueous pressure in the eye. Wireless technology reduces discomfort, risk of infection and monitor patients in remote places by providing timely health information. In order to transmit the ocular pressure through the wireless media a proposed design of wireless contact-lens antenna has been designed. The contact-lens coupled structure antenna was designed for the betterment of reflection co-efficient and for minimising the density of materials by gap-coupled configuration in comparison with the conventional on-lens loop antennas. The return loss of the designed contact lens antenna was 21 dB at 2.6 GHz with a diameter ranging from 14 to 15 mm. The simulation result of designed antenna return loss was obtained using advanced design system. The measured antenna return loss, radiation pattern and current distribution will be demonstrated in this paper, which are suitable for application of wireless ocular physiological monitoring.

Design of wireless contact-lens antenna for intraocular pressure monitoring

Intraocular pressure is an important aspect in the evaluation of patients at risk from glaucoma. Glaucoma is an ocular disorder that results in the damage of optic nerve, often associated with increased aqueous pressure in the eye. Wireless technology reduces discomfort, risk of infection and monitor patients in remote places by providing timely health information. In order to transmit the ocular pressure through the wireless media a proposed design of wireless contact-lens antenna has been designed. The contact-lens coupled structure antenna was designed for the betterment of reflection co-efficient and for minimising the density of materials by gap-coupled configuration in comparison with the conventional on-lens loop antennas. The return loss of the designed contact lens antenna was 21 dB at 2.6 GHz with a diameter ranging from 14 to 15 mm. The simulation result of designed antenna return loss was obtained using advanced design system. The measured antenna return loss, radiation pattern and current distribution will be demonstrated in this paper, which are suitable for application of wireless ocular physiological monitoring.

Wide Band Designs Of Equilateral Triangular Microstrip Antennas With Parasitic Sectoral Patches

Proximity fed equilateral triangular microstrip antenna is discussed which yields bandwidth of 498 MHz (37.53%) with peak gain of above 8 dBi. To enhance the bandwidth and gain of equilateral triangular patch without increment in its area, gap-coupled configurations with 300 Sectoral patches are proposed. A gap-coupled configuration with pair of 300 Sectoral patches yields bandwidth of above 570 MHz (>45%) and that with two pairs of 300 Sectoral patches, a bandwidth of above 640 MHz (>48%) is obtained. The gap-coupled configuration with two pairs of 300 Sectoral patches yields peak broadside gain close to 9 dBi. Thus with marginal increase in total patch area, gap-coupled design yields bandwidth enhancement by 10% with larger peak gain.

Broadband proximity-fed square-ring microstrip antennas

The fundamental and higher-order modes of a compact ring microstrip antenna are discussed. This provides insight into the functioning of this configuration. To increase its bandwidth and gain, various broadband proximity-fed configurations of a ring microstrip antenna in the 1000 MHz frequency band are proposed. A detailed explanation for the broadband behavior of all these configurations is presented. The proximity-fed square-ring antenna yielded a bandwidth of more than 250 MHz. A further increase in its bandwidth was realized by cutting a pair of rectangular slots on the edges of the ring patch. The pair of slots reduced the orthogonal TM02 mode's resonance frequency of the patch and, along with the fundamental TM10 mode, yielded a bandwidth of more than 350 MHz. Furthermore, the proximity-fed gap-coupled configurations of rectangular-slot-cut C-shaped patches, which were derived from the ring patch, are proposed. These yielded a bandwidth of more than 500 MHz (>43%). Both of these slot-cut compact configurations gave broadside radiation patterns with gains of more than 6 dBi over the bandwidth. To further increase the gain and bandwidth of the slot-cut ring antenna, a multi-resonator configuration with parasitic ring patches, gap-coupled along the two coordinate axes, is proposed. This configuration yielded a bandwidth of more than 400 MHz with a peak gain of 9 dBi. In this configuration, a further increase in the bandwidth was realized by cutting a pair of rectangular slots on the edges of the ring patches that were gap-coupled along one of the coordinate axes. This configuration gave a bandwidth of more than 500 MHz with a peak gain of 9 dBi.

Broadband proximity fed ring microstrip antenna arrays

Various gap-coupled array configurations of ring microstrip antennas and rectangular slot cut ring microstrip antennas with proximity fed slot cut ring microstrip antenna for larger bandwidth and gain are proposed. The rectangular slot in ring patch reduces its orthogonal TM01 and TM02 mode resonance frequencies and along with TM10 modes of fed and parasitic ring patches, yields broadband response. The gap-coupled configuration with ring patch and slot cut ring patch yields bandwidth of nearly 430MHz with broadside radiation pattern and peak gain of more than 9dBi. By gap-coupling ring patches along all the edges of proximity fed pair of slot cut ring patch, a 3×3 ring microstrip antenna array is realized. It yields bandwidth of more than 460MHz with peak gain of more than 10dBi. To further improve upon the bandwidth, a 3×3 array of ring patches in which rectangular slot is first cut on the edges of ring patch which are gap-coupled along x-axis and further cut inside the patches which are gap-coupled along x and diagonal axes, is proposed. Both of these configurations yield bandwidth of more than 500MHz (>45%) with a peak gain of around 10dBi.

Broadband Gap-coupled Variations of Equilateral Triangular Microstrip Antennas

Various broadband multi-resonator gap-coupled configurations of equilateral triangular microstrip antenna and its compact variation, half equilateral triangular microstrip antenna, are proposed. The broadband proximity fed equilateral triangular microstrip antenna yields bandwidth of more than 650 MHz (~44%), whereas equivalent proximity fed gap-coupled half equilateral triangular microstrip antennas yields bandwidth of more 700 MHz (~47%). The bandwidth of proximity fed equilateral triangular and half equilateral triangular microstrip antennas is further increased by using gap-coupled configurations with equal and unequal dimensions compact half equilateral microstrip antennas. These gap-coupled configurations yields bandwidth of more than 800 MHz (>50%) with broadside radiation pattern and peak gain of nearly 8 dBi.

Microwave measurements of dielectric properties using a gap-coupled multi-mode coaxial resonator

The paper describes the measuring cell based on a gap-coupled multi-modes coaxial resonator. The role of coupling effect in forming the spectra of longitudinal odd modes has been analyzed using the circuit model of the gap-coupled resonator. The relative dielectric constant εr′ and the loss tangent tanδ of a material under test are derived from the measured input reflectance employing the least-square formulation and non-linear optimization. Experimental results are presented for the samples of crude oil with varying water content in the range 0–25%. The use of the gap-coupled configuration offers a possibility of easily adjustable coupling coefficient resulting in an application of the same measuring cells for microwave characterizations both low loss and lossy liquids and solids in a wide frequency range.

Broadband Slot Cut Gap-coupled Proximity fed E-shaped Microstrip Antenna

Bandwidth of proximity fed E-shaped microstrip antenna has been increased by gap-coupling pair of rectangular slot cut rectangular microstrip antennas along its radiating edges. The patch and slot dimensions were optimized to cover 800 – 1200 MHz frequency band. In this paper, a detail analysis to study the effects of slot and patch dimension on the broadband response in desired frequency band for the gap-coupled configuration is presented. The pair of rectangular slots reduces the resonance frequency of orthogonal TM02 mode of the parasitic patch and along with the modes of the E-shaped patch yields broadband response. The variation in patch dimension of E-shaped patch increases the resonance frequencies of the modes of E-shaped patch which also optimizes the impedance for the broadband response. The slot also modifies the directions of surface currents at TM02 mode and re-orients them along patch length. Thereby it gives broadside radiation pattern over the complete bandwidth