Method to Enhance Directional Propagation of Circularly Polarized Antennas by Making Near-Electric Field Phase More Uniform

Abstract

A new approach to significantly increase the uniformity in aperture phase distribution, through time synchronization in near-electric field, of circularly polarized (CP) antennas is presented. The method uses the phase of the CP electric field vectors, obtained through full-wave numerical simulations, and does not rely on any approximation such as ray tracing. The near-field data is post-processed to extract the relative phase difference that exist due to the unsynchronized rotations of the electric field vectors in a plane parallel to the antenna aperture. The phase delay is compensated with a thin time-synchronizing metasurface (TSM) that has a 2D array of time-delay cells. The method is demonstrated with a prototype made of two-port patch antenna, which is fed through a hybrid junction, and a TSM that is placed at one wavelength spacing above the patch. When TSM is used with patch antenna, its uniform phase area increases manyfold thus increasing far-field directivity from 6.8 dBic to 22 dBic.

A Shared Aperture Microstrip Antenna Array with Multiple Polarisations and Near-Field Beam Steering

“…This distance can be varied to obtain optimum results. Usually values of ℎ 𝑚 is selected to be greater than 𝜆 0 /2 to avoid It is important to mention here that it is a common practice in research community that a base antenna or array is usually accompanied by a phase correction surface (PCS) which smooths out the phase profile of the base antenna so that it has less phase variation [22]. This is done to comply with the assumption made during the design of a unit cell where the input wave is assumed to be a plane wave.…”

“…However, a PCS is an additional piece of hardware that not only contribute to the cost of the whole antenna system but also to its overall profile. Therefore, a PCS is used only when there is a large variation in the phase profile of the base antenna or array such as in the case of a dielectric resonator antenna (DRA) [22]. The phase profile of the dual polarised array presented in Section 3 is shown in Figure 30.…”

Wideband Dual-Circularly Polarized Antennas Using Aperture-Coupled Stacked Patches and Single-Section Hybrid Coupler

“…A ME dipole array fed by a hybrid coupler [33] yields a broader bandwidth than our proposed design does, but it has larger-profile and a more-complicated configuration. The F-P antennas [23], [34], [35] can achieve a high-gain dual-CP radiation with a simple configuration, but they suffer a large-profile and narrow bandwidth. Finally, due to the compact radiator and a fully-optimized feeding network, the proposed antenna has achieved the lowest SLL in comparison with the priors.…”

“…In another effort, a dual-CP antenna with an electrically small size of ka = 0.94 [22] is realized by utilizing multilayer stacked near-field resonant parasitic elements. In addition, a high-gain dual-CP radiation can be realized by constructing a Fabry-Perot antenna [23], [34], [35], which consists of a dual linearly polarized (dual-LP) patch antenna and a polarization conversion metasurface. Since the aforementioned dual-CP antennas targeted a compact size [20], [22] or employed conventional patch as the primary radiating elements [21], [23], [34], their operational bandwidths are less than 5% only.…”

Low-Profile Wideband Unidirectional Circularly Polarized Metasurface-Based Bowtie Slot Antenna

“…CP radiation is achieved in Antenna II due to the presence of the corner-truncated metasurface that converts the LP wave produced by Antenna I into a CP wave. The mechanism of CP generation and unit cell analysis of the corner-truncated metasurface patch has been investigated in [20] and [42]- [44]. The E-field (E) produced by Antenna I is resolved into two orthogonal components (E1 and E2) when it interacts with the cornertruncated metasurface in Antenna II.…”