Saad Mufti

3D electrically small dome antenna

Modifications to a 3D electrically small antenna (ESA) are presented for dual-band and wide-band performance respectively. The design is based on a recently published dome antenna with conformal meanderlines and fed by a microstrip network. By modifying both the meanderlines and microstrips, the antenna is shown to have a voltage standing wave ratio (VSWR) below 3 for the primary 2.45 GHz band and a 3.5 GHz band. By altering this new feed structure, the antenna can be shown to increase the bandwidth at the 2.45 GHz band by nearly 100 MHz for VSWR equals 3. Rapid prototyping of two antenna designs was carried out using 3D additive printed substrates metalized by Damascening conductive silver ink; the manufactured antennas are scaled up to four times the size of simulations, and offer quick validations of the simulation claims.

Efficiency measurements of additive manufactured electrically small antennas

Additive manufactured prototypes based on a novel inverted-F antenna design are presented and measured results discussed. Radiation efficiency is computed with the aid of a Wheeler cap box; the resulting ratio of the antennas quality factor to the lower limit described by Chu is shown to be 1.9 for a spherical variant. Measured and simulated S-parameter results show good agreement, with some evident discrepancies - these are explained by potential unknown changes to the powdered materials during the printing processes, and the rough surface finish of the metallization on the antennas.

Hardware implementation of directional modulation system

A directional modulation system is conceived and measurements presented to corroborate simulation results. Directional modulation adds extra security to physical layer communications by scrambling constellations via inter-symbol interference in all directions away from the desired. This is in contrast to conventional modulation systems where the signal may be intercepted in all directions, albeit with reduced amplitude and/or a corresponding phase shift.

Hardware implementation of a direction dependent antenna modulation system

The performance of a direct antenna modulation system based on continuous phase control of a four element array is presented. We highlight the potential to provide secure and multichannel communications using multilevel quadrature amplitude modulations.

3D printed electrically small planar inverted-F antenna: Efficiency improvement through voluminous expansion

An electrically small inverted-F antenna is designed, as a planar 2D antenna, and subsequently extended to a 3D profile to study the effects of voluminous expansion on the antennas gain and efficiency. 3D prototypes will be fabricated using two different additive manufacturing methods to compare and contrast the strengths of each, and benchmarked against 2D additive printed and standard lithographic fabricated samples. Simulation results show an improvement in the antenna gain from -14.0 dB to -5.6 dB from planar to 3D.

Compact Electrically Small Antenna for Smart Watch Application

With the rise in popularity of wearable gadgets and the birth of the internet of things, new challenges are presented to antenna engineers with respect to the design space available. To this end, a compact, electrically small inverted-F antenna is designed for use in a smart watch. The design is carried out in-vitro, using numerical modelling techniques, and is benchmarked against a traditional planar inverted-F antenna from literature. The novel design presented reduces the overall size of the antenna by a factor of 3.5. It has a gain of -12.7 dB, and a half-power fractional bandwidth of 32%, and is shown to operate well within the specific absorption rate regulatory limits when operated at 25 mW.

Design and fabrication of meander line antenna on glass substrate

A compact (25.4 mm × 38.1 mm × 1.0 mm) meander line antenna (MLA) printed on a Pyrex glass substrate and designed for radiating at 2.45 GHz, is demonstrated. The results of parameter optimization are presented together with an optimal set of parameters resulting in a simulated return loss of -23 dB at 2.45 Ghz. The fabricated MLA is tested and the return loss and radiation patterns are measured. Despite thinner track-widths resulting from limitations of the current fabrication technique (thermal evaporation onto photo-patterned glass substrate), the manufactured MLA performs close to the simulated design, and its performance can be further enhanced by an improvement of this technique.