Resonant Frequency Of Patch Antenna Research Articles

A monopole microwave-assisted electrochemical sensor for the detection of liquid chemicals

In this paper, a new sensor structure is presented based on a printed circuit board (PCB) monopole antenna with operating frequency of f= 2 GHz. Numerical investigation was performed in order to determine the ethanol alcohol ratio in wine and isopropyl alcohol ratio in disinfectants (sanitizers). Finite Integration Technique (FIT) based commercial high-frequency electromagnetic solver CST Microwave Studio has been used for the simulation study. The loss tangent values and dielectric constants of the samples used in the current study were obtained by KEYSIGHT brand PNA-L N5234A Network Analyzer. The proposed sensor structure was able to greatly differentiate the ethanol alcohol content in the wine and the isopropyl alcohol content in the sanitizer through the return loss values and corresponding graphs. In the design of patch antenna, the electromagnetic permittivity ratios of the samples corresponding to the alcohol ratio and isopropyl ratio are considered and the antenna dimensions along with the working frequency were optimized accordingly. In the related frequency band, permittivity values corresponding to the ethanol alcohol and isopropyl alcohol ratios exhibit a linear variation and make the sensor design possible. According to the obtained results, it was found that the changes in the resonance frequency can be associated with ethanol alcohol and isopropyl alcohol ratio inside the samples. The change of ethanol alcohol amount and isopropyl alcohol in the liquid samples tested at the resonance frequency of patch antenna is proportional to the change in the resonance frequency and they are very close to a linear characteristic.

Transverse deformation effect on sensitivity of strain-sensing patch antenna

The strain sensor based on microwave patch antenna is proposed to monitor structural strain in structural health monitoring. When patch antenna experiences deformation, the resonant frequency of patch antenna will shift. With these characteristics, the patch antenna can operate as both the strain-sensing element and communication component. This article chooses an RT-5880 rectangular patch antenna for strain measurement, focusing on its sensing performance. For distinguishing the influence of deformation in the antenna’s length direction and width direction, the numerical simulation is implemented, and then two kinds of laboratory experiments are conducted. The first approach is to paste antennas in longitudinal and transverse ways and solve the equation set. The other approach is to design another patch antenna with narrow width and compare the test results with the wide one. All results show that the influence of deformation in wide direction on sensitivity can be neglected, and the resonant frequency shift has a good linear relationship with the strain of antenna in length direction.

A New Model to Determine Effective Permittivity and Resonant Frequency of Patch Antenna Covered With Multiple Dielectric Layers

This paper reports a model to determine effective permittivity ( $\varepsilon _{\mathrm {eff}}$ ) and resonant frequency ( $f_{r}$ ) of microstrip patch antenna (MPA) covered with multiple dielectric layers. This model is augmented with a newly developed empirical expression to determine the $\varepsilon _{\mathrm {eff}}$ of multi-layered superstrates over a substrate. The development of empirical formulation makes use of conformal mapping approach (CMA) and series–parallel combination of dielectric boundaries between the ground plane and patch of the MPA. In this work, the MPA is designed on substrate having dielectric constant of $\varepsilon _{1}$ whereas the superstrate layers have dielectric constants of $\varepsilon _{2}$ , $\varepsilon _{3}\ldots \varepsilon _{\mathrm {n}}$ . It is shown that the proposed technique is able to predict the $f_{r}$ of MPA with error of 1.8%, 3.5%, and 1.4% when it is covered with a single dielectric layer with superstrate height of 4.5mm for respective conditions of $\varepsilon _{1}= \varepsilon _{2}$ , $\varepsilon _{1}> \varepsilon _{2}$ and $\varepsilon _{1} ( $\varepsilon _{1}=3.66$ , $\varepsilon _{2}=2.2$ /4.7). Furthermore, the developed technique is analyzed for distinct combination of substrate and two superstrate layers for the cases $\varepsilon _{1}= \varepsilon _{2}> \varepsilon _{3}$ , $\varepsilon _{1}= \varepsilon _{2} , $\varepsilon _{1} \varepsilon _{3}$ , $\varepsilon _{1}> \varepsilon _{2} , and $\varepsilon _{1}> \varepsilon _{2}> \varepsilon _{3}$ . Subsequently, the viability of the proposed technique is demonstrated in practical scenarios for body centric communications by considering single (e.g., jeans cotton, pure cotton, rayon, polyester, felt fabric, terry wool, and leather) and multiple (e.g., wool over jeans cotton and polyester, felt fabric over pure cotton and rayon) layers of textiles over MPA. The measurement results on various dielectric superstrates and textiles show excellent agreement with the corresponding theoretical results and thereby validate the reported theory. Finally, a comparison with the seminal works clearly shows the promise of the reported technique in this paper.

Performance enhancement of rectangular microstrip patch antenna using double H shaped metamaterial

In this paper a high performance rectangular microstrip patch antenna (RMPA) has been designed using doubleHshaped metamaterial. First, the doubleHshaped metamaterial has been designed and optimized at 5.2 GHz resonant frequency of patch antenna. It has been found that embedding of this metamaterial into the substrate beneath the reference patch antenna improves its return loss and bandwidth without changing the resonant frequency and gain. To further enhance the gain and efficiency of the metamaterial embedded RMPA a superstrate of double H shaped metamaterial has been applied at the distance of -/3 over it. Finally, a high gain, broadband and good impedance matched metamaterial inspired RMPA has been obtained. The proposed antenna was simulated and optimized using HFSS software. The prototype antenna has been fabricated and measured results of the proposed antenna are found to be in good agreement with the simulated results.

Carbon-Nanotube-Based FR-4 Patch Antenna as a Bio-Material Sensor

This paper presents the development and design of proximity coupled feed patch antenna as a bio-sensor. This sensor system consists of a two-layer Flame Retardant (FR-4) patch antenna coated with Multi Walled Carbon Nanotubes (MWCNTs) for absorbing bio-molecules. The best design of patch antenna is chosen based on simulation results using Computer Simulation Technology (CST) microwave studio software. After adding bio-material on the top of antenna and interaction with MWCNTs based on the changes in the effective dielectric constant, the resonant frequency of patch antenna is changed. Experimental results have shown 1 MHz change in resonant frequency of patch antenna upon exposure to ethanol. Based on operating frequency (5 GHz) this technique can be used in network sensor systems to measure bio-materials in future research.

A New Method for Measuring Dielectric Constant Using the Resonant Frequency of a Patch Antenna

An analytical expression is given for the resonant frequency of a rectangular patch antenna. It shows explicitly the dependence of the resonant frequency on the characteristic parameters of a patch antenna. Based on this result, a new method is developed for the measurement of the dielectric constant of a thin slab substrate. Basically, the test equipment consists of a rectangular microstrip antenna the patch of which is fed either by a microstrip line or coaxial line. From the measured resonance parameters of the rectangular patch antenna, the dielectric constant can be easily obtained. The measured values of the present method are in agreement with the precision standard cavity resonator method. Accuracy of the dielectric constant so obtained is satisfactory.