Abdullah Haskou

Design of Small Parasitic Loaded Superdirective End-Fire Antenna Arrays

This paper presents an approach for designing parasitic loaded superdirective antenna arrays. The array current excitation coefficients calculated based on Yaghjian method are used with the array input impedance matrix to deduce the required loads for transforming the array to a parasitic one. The proposed methods practical limitations are studied via a parametric analysis on dipole-based arrays. It is also applied to design two- and three-element arrays based on an electrically small antenna (ESA). Simulation results show a very good agreement between the fully driven arrays total directivity radiation pattern and the parasitic (loaded) arrays one. Simulation results also show that the array end-fire total directivity is maximal at the design frequency. Measured results are in a very good agreement with the simulated ones.

Integrating Superdirective Electrically Small Antenna Arrays in PCBs

This letter investigates integrating a two-element superdirective electrically small antenna (ESA) array in a printed circuit board (PCB). The initial array dimensions are 31 ×25 mm2, and it is integrated in a PCB of 110 ×70 mm2. Different configurations are evaluated with respect to the impedance matching, the maximum achievable directivity, and the efficiency. The obtained results show that properly integrating the array in a PCB can maintain its superdirectivity and significantly increase its radiation efficiency. Compared to the initial array, the final one achieves a gain improvement of 13.6 dB.

A design methodology for electrically small superdirective antenna arrays

This paper presents a design methodology for electrically small superdirective antenna arrays. To calculate the required current excitation coefficients the radiated electrical fields obtained from an electromagnetic simulator are integrated in Uzkov equations. The obtained parameters are, then, optimized and used for calculating the power excitation coefficients. The proposed method is deployed for designing a two-element array for an inter-element separating distance varying from 0.05λ to 0.5λ. Simulation results show that the proposed method accurately estimates the required excitation coefficients and the method is validated.

On measuring superdirective electrically small antenna arrays

This paper discusses some practical issues related to measuring superdirective Electrically Small Antennas (ESAs). To facilitate the measuring process the array is mounted on a Printed Circuit Board (PCB). Later, different configurations for connecting the coaxial cable to the array are investigated in terms of the cable effect on the antenna parameters. Simulation results show that by using an appropriate configuration, the cable effect can be mitigated and the array can be measured. Measurement results are in a good agreement with the simulated ones.

Error probability on the orbital angular momentum detection

The orbital angular momentum (OAM) is a physical property of an electromagnetic (EM) radiation, distinct from polarization, carrying a mechanical moment. In radio frequency range, OAM can be viewed as a phase gradient on the wave front. In this paper, the problem of the detection of the orbital angular momentum (OAM) order (or topological charge) for electromagnetic (EM) radiation is addressed. The OAM order detection problem is first presented as a multiple hypothesis testing problem. The maximum likelihood test leading to the error probability on the OAM order detection in additive white Gaussian noise (AWGN) channel is derived when the transmitting and receiving arrays are perfectly aligned and misaligned. A simpler receiver based on fast fourier transform (FFT) is then presented. The performances of this receiver are then presented through extensive simulation runs for various degrees of misalignment between the transmitter and the receiver.

A design methodology for impedance-matched Electrically Small parasitic superdirective arrays

This paper presents a method for designing impedance-matched parasitic superdirective Electrically Small Antenna (ESA) arrays. The proposed method uses the current excitation coefficients for calculating the required loads for the parasitic elements. The proposed method is validated via the design of a parasitic two-element superdirective ESA. The array has total dimensions of 54×24mm2 and it achieves a maximum directivity of 7dBi.

Designing a stacked three-element parasitic superdirective antenna

In this paper we investigate designing a stacked three-element antenna arrays for UHF band. The array is based on miniaturized printed half-loop antenna integrated in a PCB of 8 × 8cm2. To study the inter-element distance effect on the antenna performance (directivity, input impedance and radiation efficiency), a parametric analysis is performed. The obtained results show that for small distances high directivities can be achieved in the case of the fully driven element. However, to transform this array to a parasitic (loaded) one, negative resistances are required and neglecting these resistances significantly decrease the antenna directivity. The results are validated via measurements.

A compact circularly-polarized array based on superdirective elements

In this paper, a new strategy for designing compact Circularly-Polarized (CP) arrays is proposed. This approach consists of using small parasitic superdirective arrays as unit elements. An array is designed for 866MHz RFID band and a parametric analysis on the inter-element distance is performed to highlight the trade-offs between the antenna-dimensions, -directivity and radiation efficiency. For total dimensions of 220 × 220 × 25.8mm3(0.58λ × 0.58λ × 0.075λ), the array has a CP directivity of 10.3dBic and a radiation efficiency of 38.5%.

Small 3D array design using superdirective antennas

In this paper, we present a compact broadside superdirective antenna array based on a planar parasitic superdirective unit-element. The array is designed for 905MHz frequency band, its dimensions are 200 × 54 × 24mm3 (0.6λ × 0.16λ × 0.07λ), and it presents a directivity of 9.2dBi and radiation efficiency of 8.3%. Integrating the initial parasitic array in a PCB of 110 × 70mm2, the array total dimensions are 200 × 110 × 70mm3(0.58λ × 0.32λ × 0.2λ), and it presents a directivity of 9.8dBi and radiation efficiency of 64%.

A wide-band miniaturized loaded Inverted L Antenna

This paper presents a wide-band miniaturized loaded Inverted L Antenna (ILA). The antenna originally resonating around 2.3GHz is impedance matched at 910MHz by incorporating a secondary port in it. This port is loaded with a parallel RL load. The antenna is printed on 0.76mm-thick Rogers RT/duroid 5880 substrate. Its dimensions are 20 × 10mm²(λ/16.5 × λ/33) and it is mounted a PCB of total dimensions of 100 × 60mm²(λ/3.3 × λ/5.5). The antenna presents a simulated-bandwidth of 63MHz and radiation efficiency of 45.7%. The measured results are in a very good agreement with the simulated ones.