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This paper proposes wide band circularly polarized slot antenna with circular stub and corner truncation. Size of this antenna is 25 mm x 25 mm x 1.6 mm on FR4 substrate. On one side of the substrate, non uniform width microstrip line is asymmetrically placed at low current density point to serve as a feed. This avoids design of a balun (balanced-to-unbalanced transformer). On the other side, truncated corner slot with circular stub is used. Circular stub produces circular polarization and the truncation at one corner further enhances the band width. Experimental results confirm the simulated results for the impedance band width from 3.18-19.27 GHz. Circularly polarized waves are also supported in the frequency range of 4.7-6.7 GHz. The maximum gain in the operational band is 5.37 dBi. The advantage of proposed architecture is compact, does not require balun design and operates for both linear and circular polarizations in C-band. [ABSTRACT FROM AUTHOR]

This paper proposes a simple microstrip patch antenna (MPA) that can reconfigure its polarization states from linear to circular polarization in real-time by means of a PIN diode. An antenna is fed by a 50 O coaxial cable through the substrate of Teflon with relative permittivity of 2.15. The proposed antenna possesses a simple patch with a one-sided corner truncated to achieve polarization reconfigurability. A PIN diode is loaded to connect the main patch with a truncated corner and further maintain dual polarization states such as linear polarization (LP) and circular polarization (CP). Advanced design system (ADS) was used as a simulator to simulate the antenna, and a good understanding was obtained between simulated and measured results. Measured results showed a good agreement with simulated results at all working frequencies of interest. It shows minimum reflection coefficient gain with -10 dB scattering bandwidth 100 MHz for LP states and 170 MHz for CP states. It also shows an axial ratio of 1.56 dB for CP, and the cross-polarization level is also in a satisfying range. [ABSTRACT FROM AUTHOR]

In this work, a novel single-feed stacked microstrip antenna is proposed for high gain and dual polarization application. The designed antenna is useful at two purposes. In one hand, its lower operating frequency demonstrates high gain and on the other hand, the upper operating frequency shows circular polarization. The proposed design consists of two pairs of small parallel slots on the radiating surface as well as in the ground plane with a view to achieving significant amount of gain (approximately 8.3 dB) at its lower operating frequency (~ 6 GHz). An interesting aspect of this work is its polarization diversity. The designed antenna is capable of showing circular polarization at its upper operating frequency (~ 6.8 GHz). At this frequency, the axial ratio of the antenna has been kept below 3 dB for circular polarization applications. This circular polarization has been introduced by truncating the corners of radiating patch at different shapes. High gain and dual polarization play a major role on different antenna performance parameters. This antenna meets these two applications simultaneously. A prototype has been fabricated and characterized in order to validate the results. An outstanding agreement between experimental results and simulated results is achieved. [ABSTRACT FROM AUTHOR]

A novel reconfigurable microstrip-fed patch antenna with polarization agility in either of two bands is proposed in this communication. Frequency reconfigurability is achieved by connecting an additional small patch to the main patch through a p-i-n diode. Each corner is cutoff from the main patch through a narrow L-shaped cut to get polarization reconfigurability. In addition, the impedance and axial ratio bandwidths are enhanced by using the proximity-coupled feed. Both prototypes are designed, fabricated, and tested. The measured results agree well with the simulated results in all cases. Also, the proposed microstrip-fed antenna is tested at high RF input power. The proposed structures are simple, low profile, low cost, and have simple bias circuitry. The proposed antennas are capable of operating in three polarization states, i.e., left-hand circular polarization, linear polarization, and right-hand circular polarization in two frequency bands. The proposed structures are best suited for modern advanced wireless communication systems such as LTE and 5G. [ABSTRACT FROM AUTHOR]