A rectangular microstrip antenna is a narrowband, wide-beam antenna fabricated by etching the antenna element pattern in metal trace bonded to an insulating dielectric substrate, such as a printed circuit board, with a continuous metal layer bonded to the opposite side of the substrate which forms a ground plane. Common microstrip antenna shapes are square, rectangular, circular and elliptical, but any continuous shape is possible. A comparison between various feeding techniques has been done. Finally, a microstrip patch antenna at specific frequency i.e. 2.4 GHz has been designed and simulated on the design software IE3D for a better understanding of the design parameters of an antenna and their effect on the bandwidth, return loss and gain patterns. A microstrip antenna in its simplest form consists of a radiating patch on one side of a dielectric substrate and a ground plane on the other side. The top and side view of a rectangular MSA (RMSA) is shown in Figure 1.

Height, h ≤ 0.159 cm ≥ 0.159 cm Dielectric constant, єr ≥ 9.8 ≤ 9.8 Width, W Small Large Radiation Minimized Maximized

2

Figure 2 shows microstrip antenna fed by a microstrip transmission line. The patch, microstrip transmission line and ground plane are made of high conductivity metal (typically copper). The patch is of length „L‟ and width „W‟, etched on top of a substrate of thickness „h‟ with permittivity „єr‟. Typically, the height h is much smaller than the wavelength of operation, but not much smaller than 0.05 of a wavelength. The return loss curve and the 3D view of current distribution are shown in figure 5 & 8 respectively.

Microstrip line feed is one of the easier methods to fabricate as it is a just conducting strip connecting to the patch and therefore can be consider as extension of patch. It is simple to model and easy to match by controlling the inset position. Since the current is low at the ends of a half-wave patch and increases in magnitude towards the center, the input impedance (Z=V/I) could be reduced if the patch was fed closer to the center. One method of doing this is by using an inset feed (a distance R from the end) as shown in Figure 3. The return loss curve and the 3D view of current distribution are shown in figure 6 & 9 respectively.

The microstrip antenna can also be matched to a transmission line of characteristic impedance Z0 by using a Quarter-wave transmission line of characteristic impedance Z1 as shown in below Figure 4. The return loss curve and the 3D view of current distribution are shown in figure 7 & 10 respectively.

The MSA has proved to be an excellent radiator for many applications because of its several advantages, but it also has some disadvantages. The advantages and disadvantages of the MSA are given in Sections.

• They can be made compact for use in personal mobile communication. They allow for dual- and triple-frequency operations.

• Their ease of mass production using printed-circuit technology leads to a low fabrication cost. They are easier to integrate with other MICs on the same substrate. They allow both linear and Circular Polarization.

• They are lightweight and have a small volume and a low- profile planar configuration. They can be made conformal to the host surface.

• Narrow Band-width, Lower Gain, Low Power-handling capability.

Aircraft and ship antennas Communication and navigation, altimeters, blind landing systems Missiles Radar, proximity fuses, and telemetry

Prof. Mahesh M. Gadag1*, Mrs. Vidyashree Koratagi2, Mr. Nikit Gadag3 2

communication Mobile radio Pagers and hand telephones, man pack systems, mobile vehicle Remote sensing Large lightweight apertures Biomedical Applicators in microwave hyperthermia Others Intruder alarms, personal communication

1. λ0=C/fr =(3x108/2.4x109) ......…………………...= 125 mm 2. W = ..........................122rrfC= 38.03 mm

3. .............1212

1 2

121





hrreff= 4.088 4.

........8.0 264.0

258.03.0*412.0  

hLeffeff

= 0.73 mm

5. 002

1

effrfL- 2L… = 29.50 mm 6.

222)1(90WLZrrin

= 310.693 Ohm

Figure 6. Return loss curve for Inset Line Feed.

1. Resonant Frequency, fr 2.4 GHz 2. Patch Thickness, t 0.017 mm 3. Patch Length, L 29.50 mm 4. Patch Width, W 38.03 mm 5. Reference Impedance, Zc 50 ohms 6. Substrate Height, h 1.58 mm 7. Dielectric Constant, єr 4.4

2

Strip Feed 2.4 5.2 -17.95 55 Inset Line Feed 2.4 5.0 -15.95 50

Quarterwave Line Feed 2.4 5.5 -19.95 60

A Comparative study of different feeding techniques has been simulated using IE3D simulation software. The fabrication of designed Microstrip Antenna was done in the laboratory using in-house facilities. The comparison of feeding techniques shows that Quarterwave Line feeding has the highest return loss of -19.95 dB.

Shibaji Chakraborty and Uddipan Mukherjee, “Comparative Study of Microstrip Patch Line Feed Antenna Design Using Genetic Algorithms”, International Conference on Computer & Communication Technology (ICCCT)-2011.

Prof. Mahesh M. Gadag1*, Mrs. Vidyashree Koratagi2, Mr. Nikit Gadag3 2

Prof. Mahesh M. Gadag received Bachelor of Engineering in Electronics and Communication Engineering in 1987 and M.Tech from NITK, Suratkal in 1992.Worked as Asst. Professor at Defense University, Ethiopia and as Associate Professor at Al-Fateh University, Tripoli. Currently working as Associate Professor at HIT, Nidasoshi. Field of research includes RF antennas and Optical Communications. Nikit Gadag is pursuing his M S in Electrical and Information Technology at Otto Von Guericke University, Magdeburg, Germany since 2015. His research fields of interest are Microwave antennas and waveguide transitions.

Assco. Professor, HOD, Dept. of ECE, Hirasugar Institute of Technology, Nidasohi, Karnataka, India