Affum Emmanuel Ampoma

Broadband circularly polarized square slot antenna with a G-shaped feedline

This paper presents the design of a compact circularly polarized square slot antenna fed by a G-shaped strip feedline. The 3-dB axial ratio (AR) band can be achieved by simply extending the feedline with a G-shaped monopole. To extend the AR bandwidth achieved by the G-patch, perturbations in the form of a U-strip and an L-shaped slot are introduced in the wide slot and ground plane respectively. Measured results showed a wide 3-dB axial ratio bandwidth of 37.1% (4.5–6.55 GHz) and an impedance bandwidth of 70.1% (3.32–6.95 GHz). The proposed antenna is suitable for wideband circular polarization applications in the IEEE C-band.

On massive MIMO antenna topologies using total power in the azimuth and zenith domains

In this paper, we present an approximate expression for the spatial correlation of massive MIMO antenna topologies. The underlying concept of the proposed model is that the total power is relative to the true distribution of power in the azimuth and zenith domains. Simulation results using measured distribution of angles of departure (AOD) support the existing fact that massive MIMO convergence metrics do not demonstrate any sensitivity to antenna topology.

Tri-band planar monopole antenna with dual band circular polarization

A tri-band planar monopole antenna with dual band circular polarization for 3G, WiMAX and WLAN applications is presented. The antenna consists of monopole arms on one side of an FR4 substrate attached to a slotted feedline and a slotted ground plane on the other side of the same substrate. The antenna has a total size of 25 × 35 × 1.6 mm3. Measured results show that the antenna has a −10 dB impedance bandwidth of 9.7% (2.05–2.26 GHz) for the lower band, 11.3% (3.41–3.82 GHz) for the middle band and 60.2% (4.89–9.11 GHz) for the upper band. The simulated axial ratio (AR) bandwidths are 4.4% (3.55–3.71 GHz) and 57.9% GHz (4.69–8.52 GHz).

Three-Dimensional Spatial Fading Correlation of Uniform Rectangular Array Using Total Power of Angular Distribution

In this letter, we derive a closed-form expression for the spatial fading correlation (SFC) of a uniform rectangular array useful for evaluating correlated-based stochastic models. The underlying concept of the proposed model is that the true distribution of power is relative to the total power of the incident wave and dependent on azimuthal and elevation spreads. Verification is accomplished with the help of computer simulation where excellent agreement is found between theoretical and simulation results. Results support the existing developments that the SFC decreases as the antenna separation or azimuthal spread increases. For performance evaluation, we model the multiple-input–multiple-output channel on the assumption that the coupling matrix of the coupled receiving array differs from the decoupled array. Results highlight the promising potentials of the proposed model with an effective decoupling process. However, we observed that lower estimations of azimuthal spread and elevation spread increase the rate of deterioration in the bit error rate and not antenna spacing.

Antenna selection with decoupling network for small receiving monopole array in a correlated MIMO system

Antenna selection in MIMO system can be considered as a generalization of the selection diversity, where an arrangement of antennas with the maximum instantaneous channel gains is selected. It reduces the hardware complexity of transmitters and receivers by utilizing fewer RF chains than the quantity of antenna elements. Antenna selection has been investigated from different angles, however, its coexistence with decoupling networks needs further investigation. In this paper we present the performance analysis of antenna selection algorithm with decoupling network in MIMO system. Mutual coupling between monopole array is characterized by the receiving mutual impedance method to formulate the decoupling network operating matrix and design. We explore system performance before and after decoupling process in a standard MIMO channel, where it is assumed that fading is correlated at the receiving side and uncorrelated at the signal source. Measurement results indicate that output voltages of decoupling network can effectively be removed off the coupling effect. Error performance and channel capacity evaluation also demonstrate the promising potentials of antenna selection algorithm with efficient decoupling scheme in MIMO system.

Performance of 40, 80 and 112 Gb/s PDM-DQPSK optical label switching system with spectral amplitude code labels

We present the performance comparison of 40, 80 and 112 Gb/s polarization division multiplexing (PDM)-differential quadrature phase shift keying (DQPSK) optical label switching system with frequency swept coherent detected spectral amplitude code (SAC) labels in simulation. Direct detection is selected to demodulate the PDM payload in the receiver. The SAC label is frequency-swept coherently detected. The label and payload signal performances are assessed by the eye diagram opening factor and bit error rate (BER) as function of received optical power (ROP) and optical signal to noise ratio (OSNR). For back-to-back (BTB) system and 156, 138 and 120 km transmission for 40, 80 and 112 Gb/s respectively, label eye opening factors are 0.93 and 0.85 for 40 Gb/s, 0.94 and 0.86 for 80 Gb/s and 0.93 and 0.90 for 112Gb/s respectively, while payload optical signal-to-noise ratio are 29.9, 25.6, 23.4 dB and the payload received optical power are -11.5, -12.6 and -13.3 dBm for a bit error rate of 10-9 after 156, 138 and 120 km for 40, 80 and 112 Gb/s respectively. The payload could well be demodulated after 1,800, 1,260 and 900 km transmission for 40, 80 and 112 Gb/s respectively at a BER of 10-3 using forward error correction (FEC).