Analysis Performance of Singly-Fed Circularly Polarized Microstrip Antenna for Wireless Communication

Abstract

The circularly polarized (CP) microstrip antennas, both of singly- and doubly-fed types, possess inherent limitation in gain, impedance and axial-ratio bandwidths. These limitations are caused mainly by the natural resonance of the patch antenna which has a high unloaded Q-factor and the frequency-dependent excitation of two degenerative modes (TM01 and TM10) when using a single feed. Many applications which require circular polarization, large bandwidth, and good performance, especially in the field of wireless communication, are still difficult to be designed by using antenna software. Some consideration to take will include the application target and design specification, the materials to be used, and the method to choose (formula, numerical analysis, etc). This paper explains and analyzes the singly-fed microstrip antenna with circular polarization and large bandwidth. This singly-fed type of microstrip antenna provides certain advantage of requiring no external circular polarizer, e.g. the 900 hybrid, as it only needs to apply some perturbation or modification to a patch radiator with a standard geometry. The design of CP and large-bandwidth microstrip antenna is done gradually, by firstly truncating one tip, then truncating the whole three tips, and finally modifying it into a pentagonal patch structure and adding an air-gap to obtain larger bandwidths of impedance, gain and axial ratio. The last one antenna structure results in a novelty because it is a rare design of antenna which includes all types of bandwidth (impedance, gain, and axial ratio) being simultaneously larger than the origin antenna. The resulted characteristic performance of the 1-tip (one-tip) antenna shows respectively 1.9% of impedance bandwidth, 3.1% of gain bandwidth, and 0.45% of axial-ratio bandwidth. For the 3-tip (three-tip) step, the resulted bandwidths of respectively impedance, gain, and axial ratio are 1.7%, 3.3% and 0.5%. The pentagonal structure resulted in the bandwith values of 15.67%, 52.16% and 4.11% respectively for impedance, gain, and axial ratio.

Analysis Performance of Triangle Microstrip Antenna for Basic Construction of Circularly Polarized-Synthetic Aperture Radar Application

“…Further, the function of two truncated-tips with length Is role as switching to change the variation of polarization, if the probe feed exist on the same place (for example probe-fed take place in the right side, if Is > Ip and Is < Ip for c2 and c3 antennas, respectively, then RHCP occur on that place). If Is = Ip, then both of c2 and c3 antennas do not have circular polarization, only linear polarization can be obtained [6].…”

“…The Method of Moments in this paper is employed to simulate the model antennas with infinite ground plane. The consideration of the efficient thickness of the antennas (seen in Figure 2 and Figure 3) allow the substrate thickness for equilateral triangle patch to be defined, that are called as single layer (h = 1.6 mm) [5,6]. The results for both c2 and c3 antennas are compared to know the improvement performance of each antenna.…”

“…The antenna is made of a thin conducting patch that the radiating patch and microstrip-line feed are located on the same layer which has thickness, h = 1.6 mm and uses a conventional substrate (εr = 2.17 and δ = 0.0009) [5,6,12,16,17]. The quarter-wave transformer is used to obtain a matching impedance of 50 Ω for Transmitter/Receiver (Tx/Rx).…”

“…Truncated-tip without slot antennas are c1, scope (c2), and hexagonal (c3), while truncated-tip with slot antenna is c3s. All of them can be applied for remote sensing application embedded on geostationary satellite after optimized and configured to array antenna [5,6,7,8].…”

“…The technique to achieve CP can be easily obtained i.e. by properly adjusting the element parameters, determining locus feed, and designing stub-fed [6,10,11]. Therefore, in the simulation of equilateral triangle antenna, the significant variation performances are also affected by stub-fed, especially S-parameter, frequency characteristic, input impedance, and radiation pattern.…”