A 2x2 integrated antenna array operating at 28 GHz with 4 GHz bandwidth is presented. Conventional PCB technology is used to realize the antenna board, with low fabrication cost by minimizing the number of layers and vias. To overcome limited bandwidth and high mutual coupling, several techniques are used: proximity coupled feedings, slotted patches, and defected ground. The S-matrix and radiation patterns of the standalone antenna prototype are measured before being attached to the IC. The performed S-matrix measurement is a very first of a kind among so far reported integrated arrays at 28 GHz. The measurements confirm a mutual coupling level less than -12 dB. This characterization is used to estimate the performance of the driving power amplifiers. The analysis confirms that the antenna array is well-matched to the IC output, and as a result, the performance of the array does not degrade under beam scanning. The integrated antenna can be used as a tile module to construct larger arrays in arbitrary configurations.

A small size and wideband circularly polarized antenna is introduced. The key innovation is that the antenna is based on four confined highly coupled microstrip patches fed by a composed right-left hand integrated feeding network. Mutual coupling is thus effectively used in a constructive way. It is shown that this idea results in an excellent combination of axial ratio (AR) bandwidth and small size. A prototype was built and measured proving the concept in practice. The impedance bandwidth is 110%, the AR bandwidth at broadside is more than 83%, and the-3 dB gain bandwidth (with respect to maximum gain) is 65%, with an overlap of 63% when considering all three at the same time. The antenna lateral size is as small as 0.52λ0×0.52λ0 where λ0 is the midband wavelength.

This communication presents a dual band circular patch antenna with improved radiation properties at GSM and WLAN frequency bands, i.e., 1.8 and 2.4GHz. The improvement has been achieved using a dual band circularly symmetric EBG (CS-EBG) structure. The structure has been simulated, fabricated and measured demonstrating notable enhancement in antenna radiation patterns at both frequency bands. Results show 5dB and 7dB improvement in front to back ratio at design frequencies of 1.8GHz and 2.4GHz respectively. In addition, measurement results demonstrate 0.8dB increase in antenna gain and significant reduction in cross polarization level at both frequency bands.Index Terms-circularly symmetric EBG, dual band, microstrip antennas, surface waves.

A dedicated antenna topology targeting wall‐mounted beam‐steered mass‐producable wireless indoor applications in the microwave band is presented. Four linearly polarised E‐shaped microstrip patches are fed by a novel Butler matrix in a 2 × 2 array configuration, realising a very simple two‐dimensional beam steering. To isolate the beam forming network (BFN) from the patches and the wall, a multilayer stripline technology was used. The proposed passive BFN consists of stripline couplers without crossings or physically separate phase shifters, leading to a BFN fitting within the same footprint as the array itself. The overall size of the Butler matrix is only 0.54λ0 × 0.54λ0 × 0.06λ0. A prototype at 6 GHz has been realised and measured, proving the validity of the concept.

This article introduces the FORMAT array, a reconfigurable millimeter-wave antenna array platform based on antenna tiles. FORMAT stands for Flexible Organization and Reconfiguration of Millimeter-wave Antenna Tiles, which is a unique hardware solution aiming to implement and demonstrate a variety of antenna array concepts, as well as different array architectures and configurations from the same basic module, providing even benchmark between different solutions and thus valuable insights into 5G and beyond-5G antenna systems. The combination of a minimum-sized 2×2 tile with 3D-printed frame parts enables antenna arrays of a variety of sizes, allows multiple beamforming architectures and a range of different antenna element positioning in the array. The hardware implementation is thoroughly described, with a few different array assemblies being manufactured and measured, validating their antenna performance with over-the-air measurements. Finally, using FORMAT hardware as both base station and user equipment, a 5 meter wireless communication link was set up, achieving 4.8 Gbps downlink speed with QAM64 modulation.