ISSN 2249-6343 International Journal of Computer Technology and Electronics Engineering (IJCTEE) Volume 1, Issue 3

Review Paper for Circular Microstrip Patch Antenna

Sonali Jain, Prof. Rajesh Nema

Abstract- In this review paper a design of an performance analysis of FR-4 substrate for high frequency microstrip antenna and inset-fed dual frequency circular microstrip antenna rectangular slot for application in wireless communication and parasitically loaded CPW fed monopole antenna for broadband operation. The circular microstrip antenna resonates at 1.58 GHz and 2.43 GHz, which enables its usage in the wireless communication domain such as in Wireless Local Area Network (WLAN).By varying the lengths of the rectangular slot, the proposed antenna can provide a tunable frequency ratio of 1.50 to 1.62 for the two operating frequency band. The performance of a low-profile coplanar waveguide (CPW)-fed monopole antenna comprising of a straight strip, a parasitic circular-hat patch, and a slotted CPW ground for broadband operation is presented. A measured dual-frequency operation with a broad impedance bandwidth(10 dB return loss) of 77% from 3.47.62 GHz, covering the required bandwidths of the lower operating band of the Japans ultrawideband (UWB), the 3.5/5.5 GHz WiMAX, and the 5.2/5.8 GHz WLAN standards,has finally been explored. Also, a stable monopole-like radiation pattern and an average antenna gain of 4.0 dBi across the operating band have been obtained.This work investigated the use of FR-4 substrate as a possible candidate for antenna design in the X-band.been designed at frequencies ranging from 2 to 10 GHz.For this purpose single element microstrip antennas have The variations in the antenna performance due to frequency increase have been studied. Keywords- Microstrip Antenna, CPW, WiMAX

I. INTRODUCTION
Microstrip antennas have profound applications especially in the field of medical, military, mobile and satellite communications. Their utilization has become diverse because of their small size and light weight. Rapid and cost effective fabrication is especially important when it comes to the prototyping of antennas for their performance evaluation. As wireless applications require more and more bandwidth, the demand for wideband antennas operating at higher frequencies becomes inevitable. Inherently microstrip antennas have narrow bandwidth and low efficiency and their performance greatly depends on the substrate parameters i.e. its dielectric constant, uniformity and loss tangent. .

In this regard several comparative studies have been performed e.g. in an Current study investigated the use of FR-4 substrate for microstrip antennas at different frequencies (2, 4, 6, 8and 10GHz) The rationale behind this research was to study the FR-4 substrate as a possible candidate for the design of microstrip antenna array in X-band and to satisfy simulated and measured results in close approximation. FR-4 has been chosen for this study because of its low cost and convenient availability hence can be used for microstrip antenna array prototyping. Microstrip patch antennas are attractive for their well-known efficient features such as compatibility with monolithic microwave integrated circuits (MMIC), light weight, less fragile, low profile etc. The main disadvantage associated with microstrip patch antennas is the narrow bandwidth, which is due to the resonant characteristics of the patch structure. But on the other hand modern communication systems, such as those for wireless local area networks (WLAN), as well as emerging applications such as satellite links (vehicular, GPS,etc.) often require antennas with low cost and compactness, thus requiring planar technology. Due to the light weight of the microstrip patch antennas, they are appropriate for the systems to be mounted on the airborne platforms such as synthetic aperture radars (SAR) and scatterometers. Because of these applications of the microstrip patch antenna, a new motivation is evolved for research and development on indigenous solutions that overcome the bandwidth limitations of the patch antennas. In applications in which bandwidth enhancement is required for the operation of two separate subbands, an appropriate alternative to the broadening of the total bandwidth is represented by dual-frequency microstrip antenna, which exhibits a dual-resonant behavior in a single radiating element. In this paper, a simple dual-frequency inset-fed circular microstrip antenna with a rectangular slot for the application in the WLAN is proposed. The radius of the antenna is 25 mm. . In this communication, considering a slotted patch antenna fed by a CPW structure can exhibit broad bandwidth, lower dispersion, lower radiation loss, and in particular can also easily be integrated with a broadband fiber optical system, a simple and low-profile broadband CPW-fed monopole antenna with a parasitic circular-hat patch and a slotted ground plane simultaneously suitable for the Japans UWB lower band (3.44.8 GHz) operation, the 3.5/5.5 GHz(3.43.69 GHz/5.255.85 GHz) WiMAX operation, and the 5.2/5.8GHz (5.155.35 GHz/5.7255.825 GHz) WLAN operation is proposed.

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ISSN 2249-6343 International Journal of Computer Technology and Electronics Engineering (IJCTEE) Volume 1, Issue 3 Though the proposed antenna was initially conceptualized from referring the prototypes reported in works, we found that with use of a further simplified slotted-ground structure in the proposed design, the antenna, comparing to the already reported antennas with the similar function can effectively provide not only a much wider impedance bandwidth but also a larger size reduction. This section describes design methodology for a circular microstrip antenna. The generic antenna layout highlighting the main design parameters and dimensions, where R is the radius of the circular patch, FR is the radius where the desired input impedance is calculated, L is the length and W is the width of the feed line. The feed line is a quarter-wave transformer to match the input impedance of the patch to 50 ohm. The distance G between the radiating element edge and the ground edge is 0/4 according to [9].The commercially available FR-4 substrate was used in the antenna fabrication. These parameters are used in the design procedure for determining the radius and input impedance of the circular patch antenna.

II. ANTENNA STRUCTURE AND DESIGN

Shows the proposed antenna configuration. The basic antenna structure is a rectangle patch with dimensions (LW) of printed on one side of a low-cost and easy-acquirement FR4 epoxy substrate with relative permittivity() 4.4 and substrate thickness 0.8 mm open-end circular ring slot and an inverted-U-shaped slot were embedded into the rectangle patch, and thus resemble the antenna structure as a CPW-fed strip monopole parasitically loaded with a circular-hat patch. Here, the used ring slot having an inner and an outer radius of ri and r0, respectively, was concentrically situated at the centre of the rectangle patch. The monopole element is a straight strip with dimensions of length Lf and width Wf, and has gap distances of d and s, respectively, to the ground and the circular-hat patch. For further improving the antennas matching condition, two horizontal short slots with the same size of LsWs were embedded into the grounds left and right inner edges at the centre position along the vertical direction. The moment method code, IE3D, was used for required numerical analysis to examine the performance of the proposed antenna configurations in terms of achieving the broad bandwidth. Via iterative trials, dimensions of the antenna with good broadband operation were finally obtained and tabulated in Table I. Note that for the feeding portion the strip width of Wf =2.2mm and gap distance of d=0.3mm were both obtained on leading to a characteristic impedance of 50 , whereas the length Lf=15mm for the strip monopole was selected referring to the one-quarter wavelength of the desired operating frequency around 5 GHz. .

Where Fr is the resonance frequency in Hz,r is the substrate dielectric constant and h is the substrate thickness in cm. shows the geometry and configuration of a single frequency inset-fed circular microstrip antenna. The antenna (referred to as antenna 1 in this paper) was fabricated on an h=1.6 mm FR4 epoxy substrate with the dielectric constant r=4.4 and loss tangent tan=0.002. As shown in the figure, a microstrip transmission line is used to feed the circular microstrip antenna. The feed is inserted deep into the circular radiating element for the proper impedance matching. This arrangement for the feeding a microstrip antenna is known as the inset-feeding. The electromagnetic software IE3D is employed to perform the design and optimization process. The design parameters are W=75 mm, L=80 mm, n =37 mm, g=1.0 mm, wf=3.05 mm and R=25. The inset length of the microstrip feed line is fixed at n=37 mm, which is 1.48 times(1.48R) of the radius of the circular microstrip antenna.

Fig1-Geometry of the proposed broadband CPW-fed monopole antenna with parasitic load.

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ISSN 2249-6343 International Journal of Computer Technology and Electronics Engineering (IJCTEE) Volume 1, Issue 3

Fig:- Geometry of antenna

III. RESULT ANALYSIS

The VSWR characteristics of the antenna 1. The value of VSWR at the first resonance frequency 1.61 GHz is 1.10. This depicts that there is good impedance matching between inset-fed microstrip transmission line and the circular radiating element in the frequency band from 1.59 GHz to 1.64 GHz. From the Fig. 4 the variation of the input impedance versus frequency of the inset-fed circular microstrip antenna can be seen. At 1.61 GHz, the value of imaginary part (reactance) of the input impedance is almost 0- and simultaneously the value of real part (resistance) is approximately 50- .Hence, from the graph it is clear that there is proper impedance matching occurs at the first resonance frequency i.e. at 1.61 GHz. In order to have a meaningful comparison between the simulated and measured results, the fabricated antennas are evaluated by extracting their S11. The simulated and measured data are over lapped in order to have better insight for comparison.

TABLE 1:Literature Review Table

Name Performance analysis FR-4 substrate for high frequency microstrip antenna of with a An Inset-fed Dual-Frequency Circular Microstrip Antenna Rectangular Slot for Application Wireless Communication in Parasitically Loaded CPW-Fed Monopole Antenna for Broadband Operation

2-10Ghz Frequency

1.584-2.43Ghz

3.4-7.62Ghz

9.2 Bandwidth Slot length Resonance Frequency 40.6mm 10Ghz

2.5-2.07

4.19

25mm 2.42Ghz

15mm 7.62Ghz

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ISSN 2249-6343 International Journal of Computer Technology and Electronics Engineering (IJCTEE) Volume 1, Issue 3

IV. CONCLUSION
This study provided an insight in determining the performance of microstrip patch antenna fabricated on FR-4 substrate. From the results presented it is observed that FR-4 can be used for X-band antenna designs. An inset-microstrip-line-fed dual-frequency circular microstrip antenna with a rectangular slot for using in wireless applications such as wireless local area network (WLAN) has been demonstrated. A novel low-profile broadband CPW-fed parasitic-loaded and slotted monopole antenna has been presented with theoretical and experimental results. The effects of existences of the parasitic element and the ground slots on both the antennas resonance and matching condition have also been investigated. This study provided an insight in determining the performance of microstrip patch antenna fabricated on FR-4 substrate. From the results presented it is observed that FR-4 can be used for X-band antenna designs.

REFERENCES
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