A Novel Wideband Beamforming Antenna for 5G Applications by Eliminating the Phase Shifters and Crossovers from the Butler Matrix

Abstract

In this study, a novel Switched Beam Antenna (SBA) system is proposed and experimentally validated for C-band applications. The system is made up of a 4 × 4 Butler matrix, whose outputs are connected to four square-looped radiator antenna elements. The originality of the proposed work depends on the construction of a miniaturized beamforming network with minimal complexity, low loss, and low expense. Moreover, designing a system with a broad frequency range enables its use in a variety of applications. Miniaturization is achieved by eliminating the crossover and integrating the 45 • shifter into the 90 • hybrid coupler, as well as tilting the antenna array (i.e., making the Butler matrix output and the feed line of the antenna element orthogonal). The simulated results of the phase difference between the suggested Butler matrix outputs closely match the −45 • -135 • theoretical calculations. The SBA measured results show a wide bandwidth and low insertion loss of 63.64% (4.21-8.14 GHz) and −4.89 dB, respectively. Four orthogonal beams are produced by the proposed structure's input ports 1-4 when they are excited. These beams are aligned at angles of −10 • , 60 • , −60 • , and 10 • at 5.7 GHz.

Compact, Ultra-Wideband Butler Matrix Beamformers for the Advanced 5G Band FR3 – Part I

“…Specifically, to match for example, PS port P1 to HC port P2 (Figure 8) it should be ZA= Z HC m2 and ZB= Z PS m1, while to estimate the matching reference line connecting the HC's port P3 to the next HC's port P1 it should be ZA= Z HC m3 and ZB= Z HC m1. Except the characteristic impedance of the TLs, the electrical length of them is also estimated using equation (17) given in [33]. However, for the BM in Figure 8 only the length of the TLs connecting the HCs ports to the input connectors (1L, 2R, 2L and 1R) is determined.…”

“…The recent advancements in 4×4 BM are summarized in Table 1 and those of 8×8 BM are depicted in Table 2. These approaches are grouped into single-layer (SL) [13][14][15][16][17][18][19] and multilayer (ML) [20][21][22][23][24][25][26][27][28][29] configurations. In [13,14] artificial transmission line branch line coupler (BLC) and swapped ports coupled line coupler, respectively, are utilized to achieve a reduction in the size of the BM from 21% to 10% (0.11λ 2 -0.05 λ 2 ) when compared to the conventional BM, while maintaining a fractional bandwidth (FBW) of 30%.…”

“…In [13,14] artificial transmission line branch line coupler (BLC) and swapped ports coupled line coupler, respectively, are utilized to achieve a reduction in the size of the BM from 21% to 10% (0.11λ 2 -0.05 λ 2 ) when compared to the conventional BM, while maintaining a fractional bandwidth (FBW) of 30%. In [15][16][17], elimination of phase shifter and crossovers approach is enforced, using 45° and 90° couplers only, to build the BM. Therein, an improvement on the FBW is reported (45% -63%) with miniaturized sizes ranging from 1.41 2 0 λ -1.22 2 0 λ .…”

“…Therein, an improvement on the FBW is reported (45% -63%) with miniaturized sizes ranging from 1.41 2 0 λ -1.22 2 0 λ . While works [13][14][15][16][17] refer to 4×4 BM, in [18] a conventional 8×8 BLC BM, printed in glass substrate was presented with narrow FWB of 2.6% and large size of 33.5 2 0 λ . Nevertheless in [19] two asymmetrical 4×4 BMs consisting of BLCs are employed to form an 8×8 BM with reduced size of 4.14 2 0 λ and FBW equal to 24%.…”