Volume 74, Issue 7-8

In this paper, a cross dipole antenna is proposed, designed, and developed for satellite communication applications. The design incorporates an alternative feeding mechanism of the coaxial/probe feeding technique with balun. The primary objective of this paper is to develop the high gain antenna with an array configuration for satellite communication. The performance parameters of an antenna such as return loss, radiation pattern, gain and directivity are investigated for cross dipole antenna and 1 × 2, 1 × 4 array configurations. It operates for Ku band (12–18 GHz) and produces a high gain with low return loss. The proposed antenna has five useful bands and exhibits a peak directive gain of 13.21 dBi at 12.4 GHz with a bandwidth of 0.89 GHz. Additional bands are also offering a gain of 11.23 dBi with a bandwidth of 0.849 GHz at 10.6 GHz, 6.59 dBi with a bandwidth of 0.6 GHz at 11.5 GHz, 12.13 dBi with a bandwidth of 1.37 GHz at 14.2 GHz and 10.47 dBi with a bandwidth of 1.3 GHz at 15.8 GHz. The cross dipole antenna is analyzed for 1 × 2, 1 × 4 array configuration in order to improve the overall gain. The proposed antenna is fabricated on FR4 substrate with a dielectric constant of 4.4 and loss tangent (tan δ ) of 0.007 with the thickness of 1.6 mm. The size of the proposed antenna is 72 × 84 mm. The proposed antenna meets the requirements of an antenna which is operating at Ku band; hence, it is found to be suitable for real time applications.

A half mode substrate integrated waveguide (HMSIW) based leaky wave antenna (LWA) featuring low cross-polarization is proposed in this paper. The umbrella-shaped slot (the combination of longitudinal and transverse slots) is etched on the top layer of HMSIW LWA to get the efficient broadside radiation. The scanning range is obtained from −47° to +30° in a frequency range of 8.3 to 15.1 GHz. The cross-polarization level for the LWA is around −10 dB at broadside. In order to improve the cross-polarization levels in HMSIW LWA, two antennas are placed face to face obtaining the balanced symmetry across the longitudinal axis. Both the simulated and measured results show that the antenna is able to scan continuously from backward to forward direction with a very good low cross-polarization level. The developed prototype is capable of continuous beam scan from −29° to +32° in an operating frequency band of 9.2 to 15 GHz with a maximum gain of 13.5 dBi. The measured cross-polarization level is −30 dB which is quite low for the main beam at the broadside direction.

In this paper, a novel tri-band reconfigurable patch antenna with simple structure is presented. By changing the on-off state of only two PIN diodes, the antenna can operate in three bands, namely X-band, Ku-band, and Ka-band. The overall size of the antenna is 0.24 λ L  × 0.5 λ L  × 0.019 λ L , where λ L is the free-space wavelength of the lowest operating frequency. A prototype is fabricated and measured to verify the design. The measurement results are in good agreement with the simulation results, which indicate that the proposed antenna can be flexibly switched between three bands of 10.9–11.18 GHz, 15.65–15.9 GHz, and 32.3–33.6 GHz with stable radiation patterns.

This research proposes a novel circularly polarized (CP) reconfigurable microstrip loop antenna for 2.4–2.5 GHz advanced wireless communication using two parasitic patches and two PIN diodes. The reconfigurable antenna can alternate between right hand circular polarization (RHCP) and left hand circular polarization (LHCP) at the main beam by manipulating the ON/OFF status of the PIN diodes. Simulations were carried out for the optimal antenna parameters, and an antenna prototype was fabricated and experiments were undertaken. The simulation and measured results are in good agreement. The antenna achieves an impedance bandwidth of 2.4–2.5 GHz and unidirectional radiation pattern with a maximum gain of 5 dBic and 3-dB axial ratio for both RHCP and LHCP. As a result, the proposed reconfigurable antenna could be utilized to improve wireless communication performance. In essence, the novelty of this research lies in the utilization of parasitic patches and shorted PIN diodes to transform linear to circular polarization; and the reconfigurability of polarization between RHCP and LHCP.

In this paper, a tunable balanced-to-balanced in-phase filtering power divider (FPD) is designed, which can realize a two-way equal power division with high selectivity and isolation. A differential-mode (DM) passband with a steep filtering performance is realized by applying microstrip stub-loaded resonators (SLRs). Meanwhile, six varactors are loaded to the SLRs to achieve the center frequency (CF) and bandwidth adjustment, respectively. U-type microstrip lines integrated with stepped impedance slotline resonators are utilized as the differential feedlines, which suppress the common-mode (CM) intrinsically, making the DM responses independent of the CM ones. A tuning center frequency from 3.2 to 3.75 GHz and a fractional bandwidth (12.1–17.6%) with more than 10 dB return loss and less than 2.3 dB insertion loss can be achieved by changing the voltage across the varactors. A good agreement between the simulated and measured results is observed. To the best of authors' knowledge, the proposed balanced-to-balanced tunable FPD is first ever reported.

Mode-division multiplexing (MDM) in silicon-on-insulator platform is an emerging technology to increase the channel number of a single wavelength carrier by the number of modes and consequently increase the transmission capacity of on-chip optical interconnects. We propose and theoretically demonstrate a multimode branching structure based on the truncated Eaton lens. The proposed T-junctions efficiently convert the higher-order modes into fundamental modes; therefore, they can be potentially employed to manipulate modes in MDM systems. The designed T-junctions are implemented by varying the guiding layer’s thickness on a silicon-on-insulator platform. The three-dimensional simulations verify that the proposed structures can split the TE 2 (TE 1 ) mode into the fundamental modes with an average transmitted power of 32% (47%) in a 1550–1600 nm bandwidth.