Saravanan Manavalan

A polarization agile patch antenna resonating at 2.4 GHz ISM band is presented. The antenna is based on a rectangular radiating element along with reconfigurable parasitic patches located at its periphery of the radiating element. Two switching diodes are used to reconfigure the geometry of the radiating element. Upon proper biasing of the switching diodes the antenna attains linear or circular (LHCP/RHCP) polarization states. The entire antenna is modelled using a high-frequency structure simulator and is validated using an Agilent network analyser (N9925A) and antenna test systems for measuring impedance and radiation characteristics. Over the entire operating band, the antenna shows better impedance matching and achieves −10 dB impedance bandwidth of 100 MHz (2.40-2.5 GHz) in linear state and 85 MHz (2.41-2.495 GHz) in the circularly polarization states along with peak gain of 5.61 dBi for LP state and 4.98 dBi for CP state in the operatingrange.

In this paper, substrate integrated waveguide based filtenna operating at X band is proposed. The model is designed on a low-loss dielectric substrate having a thickness of 1.6 mm and comprises shorting vias along two edges of the substrate walls. To realize a bandpass filter, secondary shorting vias are placed close to primary shorting vias. The dimension and position of the vias are carefully analyzed for X band frequencies. The model is fabricated on Roger RT/duroid 5880 and the performance characteristics are measured. The proposed model achieves significant impedance characteristics with wider bandwidth in the X band. The model also achieves a maximum gain of 7.46 dBi in the operating band, thus making it suitable for X band applications.

This paper presents a front-end structure of a reconfigurable patch antenna for cognitive radio systems. The antenna structure consists of an Ultrawideband (UWB) sensing antenna and an array of frequency reconfigurable antennas incorporated on the same substrate. The UWB and reconfigurable antennas are fed by co-planar waveguides (CPW). The reconfigurability is achieved by rotating the series of patch antennas through a certain angle and the rotation is controlled by mechanical means using an Arduino microcontroller. The rotational reconfigurability has been preferred over MEMS switches, PIN diodes, and other lumped elements because the latter requires the need for bias lines. The entire structure is designed using High Frequency Structure Simulator (HFSS) software and the prototype is fabricated over FR-4 substrate having a thickness of 1.6mm and measurements are carried out. This antenna achieves a wideband frequency from 2 GHz to 12 GHz and distinct narrow band of frequencies by reconfigurability using single antenna consisting of different shapes spaced accurately to ensure isolation between adjacent frequency bands and each antenna element working for a bandwidth of 2 GHz for frequency from 2 GHz to 12 GHz upon a single substrate and the reconfigurable elements are controlled using a low cost Arduino microcontroller connected directly to the antenna which ensures accurate controlling of the rotation and fast switching between the antenna elements. The measured results agree with the simulated results and have less than 10 dB impedance bandwidth.

Abstract CMOS technology has reached its physical scaling limits, power consumption limits, and hence CMOS technology has to be replaced by other emerging technologies. Quantum-Dot Cellular Automata (QCA) has proven to be a better solution since it offers better scaling and low power consumption for processing digital signals. However, due to a lack of optimization support improvements, dynamical QCA paradigms require multi-layer designs and increased computations. Hence in this paper, a reconfigurable logic gate based on QCA paradigms is proposed. The design utilizes training of memory cells associated with QCA paradigms and hence can be switched between AND, OR, and MUX logic circuit designs dynamically. Compared to traditional dynamical QCA, the model is designed on a single-layer substrate with a minimum number of cells and size.

Due to recent advances in nanotechnology, the use of nano-devices and its<br />network becomes more popular in the field of medical, commercial and<br />military applications. One of the major issues in designing nano-network is<br />miniaturization of nano-devices which are limited due to communication<br />antenna used in that device and its power constraints. At 1000nm size, an<br />antenna resonates at around 100 THz which suffers from greater propagation<br />loss and provides signal coverage of micrometer distances. Hence there is a<br />need for nano-antenna with reduced size and also operating at mid infrared<br />frequencies to provide a good signal coverage. In this paper, graphene-based<br />nano-antenna is presented. The model resonates at 55THz frequency with a<br />peak gain of 5.47 dB in the propagation direction. The model exploits the<br />principle of surface plasma polarition waves for miniaturization and achieves<br />50% size reduction when compared to conventional nano-antenna and best<br />suitable for nano-network communications.

A single fed circularly polarized reconfigurable patch antenna is proposed. The antenna consists of a radiating patch incorporated with an H-shaped slot at its center. Four ultra-miniature switches are used for polarization reconfiguration. The antenna is designed to operate at the center frequency of 2.357 GHz. The antenna achieves either left-hand polarization or right-hand polarization depending upon switching of corresponding switches. The antenna parameters are simulated using Ansoft high-frequency structure simulator and are validated using an Agilent network analyzer (N9925A) and antenna test systems. The antenna achieves a good impedance match of 120MHz between 2.26GHz – 2.38GHz band and achieves low cross-polarization isolation of -22.82 dB for RHCP and -21.77 dB for LHCP configurations at its operating frequency. The antenna finds application in areas of modern wireless communication.

Due to recent advances in nanotechnology, the use of nano-devices and its<br />network becomes more popular in the field of medical, commercial and<br />military applications. One of the major issues in designing nano-network is<br />miniaturization of nano-devices which are limited due to communication<br />antenna used in that device and its power constraints. At 1000nm size, an<br />antenna resonates at around 100 THz which suffers from greater propagation<br />loss and provides signal coverage of micrometer distances. Hence there is a<br />need for nano-antenna with reduced size and also operating at mid infrared<br />frequencies to provide a good signal coverage. In this paper, graphene-based<br />nano-antenna is presented. The model resonates at 55THz frequency with a<br />peak gain of 5.47 dB in the propagation direction. The model exploits the<br />principle of surface plasma polarition waves for miniaturization and achieves<br />50% size reduction when compared to conventional nano-antenna and best<br />suitable for nano-network communications.

A single feed circularly polarized patch antenna is presented. The antenna consists of a rhombus-shaped slot incorporated in the radiating patch at its center. The antenna is designed to operate at 2.3 GHz band. The antenna achieves left-hand polarization or right-hand polarization based on the orientation of the slot in the radiating patch. The antenna parameters are synthesized using a high-frequency structure simulator and its characteristics are validated by the Agilent network analyzer (N9925A) and antenna test systems. The measured results obtained agree with simulated results and show that the antenna achieves −10 dB impedance bandwidth of 85 MHz (2.27 GHz–2.355 GHz) for left-hand polarization and 85 MHz (2.26 GHz–2.345 GHz) for right-hand polarization. The antenna gives a 3 dB axial ratio beamwidth of 95°(−35° ≤ AR ≤ 60°) for both left-hand polarization and right-hand polarization along with better 3 dB axial ratio bandwidth of 140° in the operating band. The antenna also achieves a good cross-polarization isolation of −17 dBic for both left-hand and right-hand polarization at its operating frequency. Hence, the antenna is best suited for modern wireless communication systems.

In this paper, a single fed polarization reconfigurable antenna is proposed. The antenna consists of a radiating patch incorporated with a diagonal-shaped slot at its center. Four p-i-n diodes are used for polarization reconfiguration. The p-i-n diodes are placed in diagonal slot region. The proposed antenna is designed to operate in three states – linear polarization (LP), left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) by biasing corresponding p-i-n diodes. The antenna gives measured peak gain of 6.2 dBi for LP state and 5.82 dBic for both RHCP and LHCP states. It also achieves 3-dB axial ratio bandwidth of 5.95% for both RHCP and LHCP configurations. The antenna finds application in areas of modern wireless communication.