A conformal, dynamic pattern-reconfigurable antenna using conductive textile-polymer composite

A conformal antenna with electronically tuning capability of its radiation pattern between broadside and monopole-like patterns is proposed. The antenna is based on a proximity-fed circular patch, loaded with a ring patch and four rectangular slots. The design is planar without any use of rigid shorting posts or complex feeding network. The reconfigurability is achieved by activating and deactivating the slots using PIN diodes, to switch between TM02 (monopole-like mode) and perturbed TM02 distributions (broadside mode) of the antenna. For conformability, the antenna is fabricated using highly flexible PDMS-conductive fabric composite. All the antenna parts, including the RF switches, wires, and DC biasing circuit are fully encapsulated by PDMS to provide resilience against deformation and harsh environment. Investigations on the RF performance and mechanical stability of the antenna were conducted. Under various bendings, it was demonstrated that all the antenna components, including those for electronic switching, remained intact and in working order even under radius bending of 30 mm, thus maintaining good pattern reconfigurability and overall performance. When bent, the measured results at 5.2 GHz show a stable radiation performance relative to those of the flat case (i.e., maximum gain of 2.9 dBi and efficiency of 64% in broadside mode, corresponding to 1.75 dBi and 52% in monopole-like mode). To the best of our knowledge, all these features have never been demonstrated in previously published pattern reconfigurable antennas

IEEE Access Special Section: Antenna and Propagation for 5G and Beyond

5G is not just the next evolution of 4G technology; it is a paradigm shift. “5G and beyond” will enable bandwidth in excess of 100s of Mb/s with a latency of less than 1 ms, in addition to providing connectivity to billions of devices. The verticals of 5G and beyond are not limited to smart transportation, industrial IoT, eHealth, smart cities, and entertainment services, transforming the way humanity lives, works, and engages with its environment

A wideband EBG resonator antenna with an extremely small footprint area

Erratum to article published in Microw. Opt. Technol. Lett., 57: 2228. doi: 10.1002/mop.29247. An electromagnetic band gap resonator antenna (ERA) with an extremely small footprint is presented. The proposed ERA has a peak measured gain of 15.6 dBi and an excellent measured 3dB gain-bandwidth of 27%. The four-layer composite superstructure used in this ERA takes the shape of a circular disc with the ground plane radius equal to that of the superstructure. Its footprint area is only 1.7λ0² at the lowest operating frequency. The average measured aperture efficiency of this ERA is nearly 90%. The side lobe levels are well below −12 dB over most of the operating bandwidth and the cross polarization levels are below −17 dB.5 page(s

Enhancing the performance of EBG resonator antennas by individually truncating the superstructure layers

The role of superstructure finiteness in improving the peak directivity and the directivity bandwidth (DBW) of electromagnetic band gap (EBG) resonator antennas (ERAs) is studied. Simple one- and two-layer superstructures consisting of unprinted dielectric slabs are used for this purpose. In the latter case, each dielectric slab is truncated individually to improve the ERA performance. Initially, existing analytical models that only take into account the reflection characteristics of the superstructure are used to predict the peak obtainable directivity and the directivity bandwidth. Detailed numerical studies are then conducted to observe the validity of these analytical predictions and to study the ERA performance for various finite sizes of the superstructure. It is found that DBW as well as the peak directivity of the antenna is strongly influenced by the size of the superstructure. Moreover, in case of two-layer superstructures, carefully designing each layer to have a different finite size improved the DBW product of an ERA by more than 65%. Experimental results of three ERA prototypes are presented to validate the trends observed in the numerical findings.8 page(s

Distribution profiles for transverse permittivity gradient superstrates in extremely wideband resonant cavity antennas

Transverse permittivity gradients in superstrates of extremely wideband resonant cavity antennas (RCAs) require the dielectric constant of the superstrate to change from a high value in the centre, to a low value at the edges. This paper investigates the performance of quantized permittivity gradients in such superstrates in comparison to continuous permittivity gradients. Continuous gradients are associated with high manufacturing complexity and increased cost. In this paper, two quantized permittivity distribution profiles are constructed, each with only three quantized steps to achieve comparable performance to that of piecewise-linear continuous distribution profile, while offering increased manufacturing ease. Numerical results are presented to validate the proposed concept.2 page(s

A Composite EBG resonator antenna with a sparse array feed

In this paper, we study performance of a simple electromagnetic band gap (EBG) resonator antenna (ERA) that has a composite all-dielectric superstructure and is excited by a small sparse array. The cavity of the antenna is excited by a 2×2 array of waveguide fed slots with an inter-element spacing of 1.8λo. The ERA exhibits high gain with an excellent directivity bandwidth of around 20%. The proposed configuration provides improved performance in terms of antenna gain and directivity bandwidth, while significantly minimizing design complexity. Numerical results are presented and a peak gain of 21 dBi is demonstrated.2 page(s

A Planar feeding technique for wideband, low-profile resonant cavity antennas

A low profile, wideband resonant cavity antenna (RCA) is presented. It uses a simple and planar wideband feed antenna. The use of this planar, printed feed antenna reduces the overall height of the RCA. The RCA has a single-layer superstrate, which has radially non-uniform permittivity in the transverse plane. Excellent wideband matching was obtained for the RCA with a -10dB return loss bandwidth ranging from 20.81 to 25.32 GHz. Numerical results predict a peak boresight gain of 16.97 dBi. This RCA is well-suited for scalable RCA configurations such as sparse arrays or switched-polarization arrays with printed feed networks.2 page(s

Directive beaming with lens-like superstates for low profile Fabry-Perot cavity antennas

Lens-like superstrates designed to exhibit a spatial reflectivity map are studied for use as the partially reflecting surface in Fabry-Perot cavity antennas. Profile reduction is obtained by using only a single dielectric layer of such surfaces which is found to provide improved performance than the multi-layered superstrates. The use of such surfaces results in a varied reflectivity within the cavity and makes the boresight emissions spatially coherent. This provides high boresight directivity with improved bandwidth characteristics. With this surface as super-strate of a resonant cavity antenna, performance is evaluated for a single feed exciting the cavity. Highly directive beams with 17.6dBi peak directivity and fairly suppressed side lobes are obtained over a very wide bandwidth with only a single layer lens-like surface.2 page(s

Wideband high-gain EBG resonator antenna employing an unprinted composite superstrate

A single-feed high-gain EBG resonator antenna with extremely wideband performance is presented. The bandwidth is enhanced through a novel composite superstrate made from a combination of unprinted dielectric slabs with uniform thickness. The composite superstrate leads to wide defect-mode bandwidth and offers slowly increasing reflection phase profile over a wide frequency band. A single slot is used to excite the cavity. Peak antenna gain of 17.17 dBi with half-power gain bandwidth of 33.9% centered at 12.6 GHz is predicted. More than 100% increase in 3-dB directivity bandwidth with 55% reduction in aperture size is obtained as compared to conventional designs.2 page(s