Jalil Ur Rehman Kazim

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).

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.

Strong coupling (crosstalk) between printed microstrip transmission lands on printed circuit boards

In this paper, strong coupling (crosstalk) between microstrip transmission lands on printed circuit board is investigated from an electromagnetic compatibility (EMC) point of view. Near-end and Far-end crosstalk expressions between microstrip transmission lines were derived analytically and then validated using ADS Momentum and circuit simulator. For experimental validation, three cases of coupled microstrip transmission lines (3mm, 5mm and 10mm separation) on three separate PCBs were fabricated on Rogers FR4 substrate with the relative permittivity of 4.6 and thickness of 1.6 mm. The near- and far-end crosstalk were measured using in-house Agilent network analyzer. The measured results of near- and far-end crosstalk closely match with the ADS Momentum results. The developed analytical model can be used both for weak and strong coupling computation.

A compact passive UHF RFID meandered dipole tag

This paper investigates a compact design of a meandered dipole passive ultra high frequency (UHF) radio frequency identification (RFID) tag for the Pakistani frequency band (865–868 MHz). To reduce the tag size, meandering technique and inductive complex impedance structure was incorporated in the proposed design. The overall dimensions of the tag is 0.108λ0 × 0.063λ0 where λ0 is the free space wavelength at 867 MHz. The tag was fabricated on Rogers FR4 substrate with the relative permittivity of 4.6 and thickness of 1.6 mm. The measured result of the return loss of the proposed tag agrees well with the simulated result. The proposed passive UHF RFID tag has a computed read range of 3.96 for 0.1 W ERP (Effective Radiated Power) which fulfills the criteria of passive UHF RFID read range, i.e., greater than 3 meters and less than 10 meters in a direction normal to the reader.

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.