Design and Implementation of a Miniaturized Filtering Antenna for 5G Mid-Band Applications

Abstract

Combining a microwave filter with an antenna results in a low-cost, efficient, and small-size selective radiator called a filtering antenna or filtenna. In this work, a compact filtering antenna is presented to radiate within the 5G mid-band frequencies along (3.6–3.8 GHz) with strong rejection for the frequencies outside this range. The proposed filtering antenna consists of a crescent-shaped planar monopole antenna that is electromagnetically coupled with a reduced-size capacitively loaded loop (CLL) microwave band-pass filter. The miniaturization of CLL is achieved by utilizing a single ring CLL structure instead of two rings to reduce the filter size to half without affecting the filter performance. The filtering antenna in this work is fabricated on a Rogers RT5880 substrate with dimensions equal to 24.2 × 27 × 0.8 mm3. Good congruence between the measurements and the simulation results, and both verify the antenna's perfect operation along the 5G mid-band frequency range. The simulated and measured peak realized gain values of the proposed structure are 2.24 dB and 2.2 dB, respectively. Furthermore, the power pattern of the designed filtering antenna is omnidirectional, which is very convenient for portable 5G mid-band devices. Compared to other works, it is found that in spite of the small dimensions of the filtering antenna (24.2 × 27 × 0.8 mm3), the antenna has a bandwidth that covers the range 3.6–3.82 GHz with a maximum gain value equal to 2.2 GHz and omnidirectional pattern which makes the antenna very suitable for 5G mid-band applications.

A Compact Broadband Circularly Polarized Wide-Slot Antenna With Axial Ratio Bandwidth Encompassing LTE 42 and LTE 43 Standards of 5G Mid-Band

“…The co-and cross-polarized patterns are close to each other (with a difference of less than 3dB) in the broadside direction (𝜃 = 0 𝑜 ), and this is good evidence for the presence of the CP in that direction. In general, the 5G antenna designers propose antennas for 5G mid-band either in the LTE 43 standard [23,24] or in the LTE 42 standard [25,26]. Unfortunately, these designs cannot be used in devices that works on the two standards because this requires using two different antennas for each standard.…”

Generalized Concept and MATLAB Code for Modeling and Analyzing Wideband 90° Stub-Loaded Phase Shifters with Simulation and Experimental Verifications

“…It is worth mentioning that like the other microwave phase shifters, the proposed phase shifter has the properties of the microwave band-pass filter. One of the important characteristics of the filters is that its pass band should be accompanied with a linear phase response [ 24 , 25 , 26 , 27 , 28 ], and the proposed phase shifter meets this condition properly.…”

A Compact Filtering Antenna With Step and Continuous Tuning Modes for WiMAX Cognitive Radio Communication

“…Gain (dB) Rad. Pattern [4] 0.61𝜆 𝑜 × 1.215𝜆 𝑜 × 0.0325𝜆 𝑜 -6.16-6.47 6.77 Directional [5] 0.62𝜆 𝑜 × 1.23𝜆 𝑜 × 0.033𝜆 𝑜 -6.2-6.5 5.62 Directional [7] 0.32𝜆 𝑜 × 0.3𝜆 𝑜 × 0.0165𝜆 𝑜 -3.6-3.8 1.9 Omnidirectional [10] 0.568𝜆 𝑜 × 0.568𝜆 𝑜 × 0.009𝜆 𝑜 -4.26-5.94 2.3 Omnidirectional [11] 0.364𝜆 𝑜 × 0.5408 𝜆 𝑜 × 0.016𝜆 𝑜…”

“…A miniaturized capacitively loaded loop resonator was attached to a monopole antenna to restrict the radiation of the antenna within the unlicensed industrial-scientific-medical band [6]. The same resonator was loaded by another monopole antenna to cover the 5G mid-band cellular communications [7]. The design in [8] had two filters operating alternately to switch between the sensing mode and the communication mode of the CR system.…”