Sajid Aqeel

Reconfigurable UWB monopole antenna for cognitive radio applications

A compact frequency reconfigurable UWB antenna for cognitive radio application is presented in this paper. The proposed structure has a simple design and easy construction. The antenna is made reconfigurable, by enabling or disabling the parasitic element coplanar to the main radiator. The resonance frequency of the proposed antenna operates in two configurations which is achieved by employing three ideal switches. This antenna is operational in the practically whole UWB spectrum. Antenna parameters in terms of current distribution, return loss and radiation pattern are also presented. Experimental results successfully validate the proposed design methodology in this work. The simulations were carried out in the Agilent Advance Design System (ADS).

Design of a Dual-Band MIMO Dielectric Resonator Antenna with Pattern Diversity for WiMAX and WLAN Applications

In this paper, a dual-band multiple-input multiple-output dielectric resonator antenna (DRA) with pattern diversity is presented. L-shape of the DRA produces patterns diversity at the lower band whereas, at the upper band, it is caused by exciting TEx 121/TEy 211 mode in the DRA. Two copper strips are pasted at the corner of the dielectric radiator to improve matching at both the bands. A cylindrical air-gap introduced in the radiator improves isolation up to 25 dB and 20 dB at lower and upper frequency bands, respectively. The MIMO system possesses pattern diversity and isolation without applying any special decoupling technique. The design covers the WiMAX and WLAN bands at 3.6 and 5.2GHz, respectively. Simulated and measured reflection coefficients, envelope correlation, diversity gain and mean effective gain, are in good agreement.

A Dual-Band Multiple Input Multiple Output Frequency Agile Antenna for GPSL1/Wi-Fi/WLAN2400/LTE Applications

A novel dual-band, single element multiple input multiple output (MIMO) dielectric resonator antenna (DRA) with a modest frequency tuning ability is presented in this communication. The proposed antenna operates at GPS L1/Bluetooth/Wi-Fi/LTE2500/WLAN2400 frequency bands. A single dielectric resonator element is fed by two coaxial probes to excite the orthogonal modes. A couple of slots are introduced on the ground plane to improve the isolation between antenna ports. The slots also serve the purpose of reconfiguration in the lower band on placement of switches at optimized locations. The measured impedance bandwidth is 5.16% (1.41–1.49 GHz) in the lower band and 26% (2.2–2.85 GHz) in the higher band. The lower band reconfigures with an impedance bandwidth of 6.5% (1.55–1.65 GHz) when PIN diodes are switched ON. The gain, efficiency, correlation coefficient, and diversity gain of the MIMO DRA are presented with a close agreement between simulated and measured results.

A Compact Frequency Reconfigurable Hybrid DRA for LTE/Wimax Applications

A compact hybrid antenna structure with frequency reconfiguration capabilities is presented in this article. The proposed design employs a combination of a rectangular DR element and a coupling slot on the structure’s ground plane (GP). The slot shifts the fundamental DRA mode by introducing a slow wave effect and its resonant behavior helps to achieve an omnidirectional pattern at low frequencies. The slot is loaded with a series of PIN diode switches whose ON/OFF combinations alter the effective slot length. Slot loading with PIN diodes results in frequency reconfiguration of the proposed structure with a large tuning range of 76.2% (between 1.73 and 3.86 GHz). A parametric analysis was performed to investigate the effects of slot length, width, and position on the reflection coefficients of the proposed structure. A prototype of the proposed design was fabricated and results were measured. The measured results show a close agreement with the simulated ones. The proposed design is suitable for DCS 1800 MHz, PCS 1900 MHZ, UMTS, LTE 2500–2700 MHz, and Wimax 3.5 GHz.

Corrigendum to “A Compact Frequency Reconfigurable Hybrid DRA for LTE/Wimax Applications”

A compact hybrid antenna structure with frequency reconfiguration capabilities is presented in this article. The proposed design employs a combination of a rectangular DR element and a coupling slot on the structure’s ground plane (GP). The slot shifts the fundamental DRAmode by introducing a slow wave effect and its resonant behavior helps to achieve an omnidirectional pattern at low frequencies. The slot is loaded with a series of PIN diode switches whose ON/OFF combinations alter the effective slot length. Slot loading with PIN diodes results in frequency reconfiguration of the proposed structure with a large tuning range of 76.2% (between 1.73 and 3.86GHz). A parametric analysis was performed to investigate the effects of slot length, width, and position on the reflection coefficients of the proposed structure. A prototype of the proposed design was fabricated and results were measured. The measured results show a close agreement with the simulated ones. The proposed design is suitable for DCS 1800MHz, PCS 1900MHZ, UMTS, LTE 2500–2700MHz, and Wimax 3.5GHz.

A reconfigurable dielectric resonator antenna with pattern diversity for DVB-H application

A stacked-dielectric resonator antenna (S-DRA) with frequency reconfigurability and radiation pattern diversity is presented for DVB-H application. Two metallic patches are used that can be connected by RF switches to extend the ground plane. By extending the ground plane, pattern diversity and reconfigurability is achieved. This antenna offers reconfigurability from 0.47 GHz to 0.89 GHz for return loss below -10 dB. Performance in terms of return loss, current distributions, peak gain, radiation pattern and total efficiency of the designed antenna is presented that covers UHF band IV and V, respectively.

A Pattern Reconfigurable Dielectric Resonator Antenna for Wireless Fidelity Applications

A pattern reconfigurable dielectric resonator antenna for wireless fidelity (2.4 GHz) band is presented in this communication. A rectangular dielectric resonator antenna which is fed by a microstrip line serves as the main radiating element. The pattern reconfigurability is achieved by the introduction of slots on the ground plane. The switch placement on the slots redistributes the surface currents and results in pattern reconfigurability. Six useful configurations are obtained by the ON/OFF combination of the switches with a diverse pattern and almost same resonant frequency.