Dual-Polarized Antenna With Dual-Differential Integrated Feeding for Wideband Full-Duplex Systems

Abstract

A new two-port dual-polarized planar antenna with an integrated feeding circuit for in-band full-duplex (IBFD) applications is presented. The antenna consists of four H-shape slots, stacked patches for enhanced bandwidth (BW), and a separate layer of two differential (0 • and 180 • split) power dividers connected using vertical transmission lines which define the feeding system. The multilayer antenna is well matched from about 2.2 to 2.5 GHz with isolation values from about 40 to 60 dB. When compared to similar IBFD antenna systems, the proposed configuration provides a higher isolation BW (10%) and higher gain (7.8 dBi) whilst adopting a simple feeding network. Also, by using the proposed feeding circuit, the manufactured antenna does not require any external cables and couplers. This simplifies the structure and reduces the amount of cable connections. This allows for other analog-based self-interference reduction schemes for further improvements in the transmit and receive data link. In addition, the proposed antenna design was extended to a 4×1 array. These dual-differential IBFD antenna systems are a good alternative to more conventional full-duplex designs which typically require external coupler-based feeding. In addition, the operating BWs and isolation values offered by these S-band systems can support new data link possibilities for beam steering and future IBFD wireless networks by low-cost antenna and feeding circuit integration.

Antenna/Propagation Domain Self-Interference Cancellation (SIC) for In-Band Full-Duplex Wireless Communication Systems

“…As shown in Figure 7, compared to the more widely used unbalanced feeding, differentially feed (balanced feed) an antenna can attain higher polarization purity with a cost of additional feed port. Isolation between two polarizations can be substantially increased by applying differential feed to either one of the TX/RX ports [44,45] or both the two ports [46][47][48].…”

“…As shown in Figure 7, compared to the more widely used unbalanced feeding, differentially feed (balanced feed) an antenna can attain higher polarization purity with a cost of additional feed port. Isolation between two polarizations can be substantially increased by applying differential feed to either one of the TX/RX ports [44,45] or both the two ports [46][47][48]. In [17,[49][50][51][52], by employing power dividers [53] with 180° phase shift or hybrid couplers in the feed networks, the SI is further attenuated because they create two coupling paths with out-of-phase signals that cancel with each other to some extent.…”

Dual-Linearly Polarized Magneto-Electric Dipole Antenna for In-Band Full-Duplex Applications

“…The utilisation of orthogonal polarisation in the design of the fullduplex antenna is widely adopted due to its capability to provide good port isolation. In [2], [3], [4], [5], and [6], the antennas operate in the differentially orthogonal linear polarisation and provide high isolation between the TX and RX ports by combining a single radiating element and several couplers. This method utilises polarisation diversity, which, though feasible for many commercial applications, is not acceptable for some circumstances.…”

Isolation Improvement Using the Field-Circuit Combined Method for In-Band Full-Duplex MIMO Antenna Arrays

“…In the fullduplex antenna array proposed in [23], only 30 dB isolation can be obtained. After increasing the antenna spacing, higher isolation (> 42 dB) is obtained in [24]. In [25,26], the interference between the transmitter and receiver is suppressed by integrating with the feeding network based on antiphase feeding technique.…”

“…In [25,26], the interference between the transmitter and receiver is suppressed by integrating with the feeding network based on antiphase feeding technique. However, the transmitting and receiving antennas have orthogonal polarizations in above arrays [23][24][25][26], which is not applicable for some scenarios.…”