Compact Filtering Antenna Research Articles

Compact Modified Elliptical-Shaped Ultra-wideband Filtering Antenna with Improved Band-Edge Selectivity

A compact filtering antenna with higher selectivity near band-edge frequencies for ultra-wideband (UWB) applications is presented and developed in this article. The antenna with filtering characteristics is formulated by integrating a rectangular-impedance resonator-based bandpass filter into the feedline of a modified elliptical-shaped monopole radiator. Initially, a modified elliptical-shaped monopole radiator is designed and numerically simulated to ensure the overall performance over the UWB band. The modified elliptical shape is used as a radiator to increase the electrical length while maintaining minimum physical size. The size of the UWB antenna is merely 0.518λ AL × 0.272 λ AL (where λAL is the guided wavelength at 2.62 GHz). Furthermore, to enhance the performance characteristics of the filtering antenna along with band-edge selectivity, geometrical parameters are optimized using a numerical simulation tool. It exhibits a simulated impedance bandwidth of 112% (3.05–10.81 GHz) with an electrical size of 0.676λ FL × 0.316λ FL (where λFL is the guided wavelength at 3.05 GHz). The experimental results of the fabricated UWB antenna and filtering antenna prototypes agree well with their simulated results.

Design of a compact filtering antenna with multi-adjustable radiation nulls

ABSTRACT A compact filtering antenna with multi-adjustable radiation nulls is designed. Initially, a conventional aperture-coupled antenna is crafted by fine-tuning positions of the gap and radiation patch, achieving a radiation null. Additionally, an aperture-coupled filtering antenna is created by cascading a resonator with a microstrip feedline. Subsequently, the integration of the aperture-coupled antenna and the filtering antenna results in a dual-slot aperture cross-coupling filtering antenna, with two radiation nulls at both ends of the passband. Finally, a pair of slot lines is etched on the radiation patch, introducing an extra radiation null to enhance selectivity further. The measured results show that the proposed filtering antenna has a bandwidth from 2.44 to 2.64 GHz for |S 11|<−10 dB, a peak gain of 5.5 dBi, and three radiation nulls at 2.3, 2.75, and 3.15 GHz enhancing the selectivity.

A Compact Filtering Antenna System with Wide-Angle Scanning Capability for V2I Communication

A Compact Filtering Antenna System with Wide-Angle Scanning Capability for V2I Communication

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

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

A broadband compact filtering antenna for sub‐6 GHz base station applications

A broadband compact filtering antenna for <scp>sub‐6 GHz</scp> base station applications

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

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 Dual-Polarized Filtering Antenna With Steep Cut-Off for Base-Station Applications

A dual-polarized filtering antenna with steep cut-off and compact size is developed for base-station applications. In this design, four controllable radiation nulls are obtained by utilizing split rings, slotted T-shaped branches, a single-stub tuner, and a parasitic loop. Split rings are first used as the dipole arms to obtain the first radiation null at upper out-of-band. Four T-shaped branches working as DGS are printed under the crossed dipoles to achieve the second radiation null. The connected outer conductors of the differential feed structure acting as a single-stub tuner can provide the third radiation null to further enhance the upper band rejection. Finally, a parasitic loop is incorporated around the split rings, and the out-of-band rejection of the lower band is further enhanced by the fourth radiation null. More importantly, the impedance bandwidth of the antenna can be expended with two newly introduced resonant modes. As a result, a compact filtering antenna with a wide operational bandwidth of 1.7–3.01 GHz (56%) is realized for <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert \text{S}_{dd11}\vert &lt; -15$ </tex-math></inline-formula> dB with the isolation higher than 38 dB. The out-of-band suppression is higher than 18.4 dB in 3.1–4.5 GHz and more than 47 dB in 0.8–1.1 GHz.

Compact filtering antenna using asymmetric CPW-fed based CRLH structure

Compact filtering antenna using composite right/ left-handed (CRLH) transmission line structure is presented in this paper. It utilizes a simplified asymmetric coplanar waveguide (CPW) feeding method. Initially, a bandpass filter has been designed with a circular interdigital capacitor, meander line and rectangular patches with asymmetric CPW feeding. The filtering antenna structure has been designed by replacing the rectangular patch and coupling at load side (Port-2) of the designed filter with L-shaped patch, which acts as a radiating element. The resonance frequency can be controlled by the series parameter due to shorted boundary condition of the structure. The designed filtering antenna resonates at 3.4 GHz with 10-dB impedance bandwidth of 23.5%. It provides a nearly flat gain response within the passband by the average value of 2.5 dB along with two radiation null at 2.1 GHz and 4.5 GHz. The total size of the designed structure is 0.39λg × 0.26λg at the resonance frequency (3.4 GHz) of the working band. It gives an omnidirectional radiation pattern at the resonance frequency. The designed prototype is fabricated and measurements are done for validation of simulated results and the filtering antenna is made useful for sub-6 GHz of 5G (3.3–3.6 GHz) applications.

Dual Band Filter-Antenna with Fixed Low Band and Frequency-Agile High Band for Wireless Communications

This work proposes a design of compact filter-antenna with fixed and frequency-agile bands for wireless communications and cognitive radio (CR) systems. The filter-antenna is realized by attaching a bandpass filter with an independent fixed band and a tunable band to a UWB antenna. The dual bandpass filter consists of a folded open loop resonator loaded with single varactor diode at a suitable location to achieve reconfigurability operations for the high band while the low band remains fixed at 4.5 GHz. A reconfigurable broadband frequency range of 3.2 GHz from 7.8 to 4.6 GHz is achieved for the high band by changing the capacitance of the varactor from 0.16 to 2.25 pF, respectively. A prototype of the filter-antenna is fabricated and measured at a selected capacitance of 0.6 pF to verify the simulation results. Good agreements between simulated and measured results are obtained.

A Filtering Patch Antenna With Reconfigurable Frequency and Bandwidth Using F-Shaped Probe

A wideband filtering patch antenna is investigated in this paper. The patch antenna is fed by an F-shaped probe, which consists of one upper and two lower horizontal arms, as well as a vertical arm that connects them. Owing to the novel excitation scheme, two probe modes along with a patch mode are simultaneously excited within the passband, producing a wide bandwidth of 21.3% with stable antenna gains and radiation patterns. Meanwhile, cross-coupling is constructed in the antenna, generating two symmetrical radiation nulls right at the two sides of the passband. Consequently, a compact filtering antenna with bandpass response and high selectivity is obtained, without utilizing any extra filtering circuit. This design is also extended to realize a reconfigurable filtering antenna. Two varactor diodes are embedded in the F-shaped probe to continuously tune the frequency of the operating band from 2.05 to 2.52 GHz. The antenna bandwidth can be flexibly tuned from 2.2% to 21.3%, and simultaneously good filtering performance is kept during the tuning of different states.

Integrated design of filtering antenna with high selectivity and improved performance for L-band applications

An integrated design of compact filtering antenna having high selectivity and suppressed unwanted harmonics is proposed in this paper. The proposed filtering antenna is obtained by integrating a modified elliptic-shaped monopole antenna with a modified interdigital bandpass filter (IBPF). At first, a modified elliptic-shaped monopole antenna is designed and investigated through numerical simulation and experimentally. Further, the modified IBPF reported in the literature is integrated with the proposed monopole antenna to achieve good passband selectivity and suppressed unwanted harmonics for the proposed filtering antenna. The proposed filtering antenna is analysed through numerical simulation software. The simulated −10 dB reflection coefficient bandwidth of the proposed filtering antenna covers the frequency range 1.01–1.96 GHz with improved band-edge selectivity and unwanted harmonic suppression up to 8 GHz (= 5.4 f0, where f0 is the centre frequency of passband). It has nearly stable omnidirectional radiation patterns over the whole frequency band. The proposed filtering antenna was fabricated and experimentally tested. The experimental results are nearly in agreement with corresponding numerical simulation results. The proposed filtering antenna can be a suitable candidate for various L-band wireless communication applications.

Efficient Design Methodology for a Complex DRA-SIW Filter-Antenna Subsystem

This work reports on an efficient design methodology for realizing hybrid filter-antenna subsystems. Designing a filter-antenna subsystem in the case of complex multimode filter is not straightforward. The coupling of the antenna with a multimode filter depends upon several uncorrelated parameters. An efficient design methodology is proposed which can address these complex problems. The work focuses on the characterization of radiating and filtering elements and then proposes a reliable model, which is derived mathematically as well as from rigorous statistical analyses, which can then be used for designing hybrid filter-antenna structures such as a hybrid DRA codesigned with a SIW based multimode filter. A highly compact filter-antenna subsystem has been designed employing the proposed methodology, and the measured results validate the proposed design technique.

Design of compact and miniaturize asymmetric SIR-DRA filter-antenna subsystem

The proposed work presents a compact filter–antenna subsystem design using asymmetric stepped impedance resonator filter and cylindrical dielectric resonator antenna. A cylindrical dielectric resonator antenna is excited from stepped impedance resonator through slot. The DRA is excited for HEM11 mode. Rather than utilizing customary 50 Ω interfaces, some intermediate impedance between filter and antenna is optimized to get the desired results. The assembly of both filter and antenna into one module leads to compactness in the RF front-end. The designed filter antenna subsystem has efficiency of 93%.

Compact filtering antenna using CRLH resonator and defected ground structure

A compact filtering antenna with high band-edge gain selectivity using a composite right-/left-handed (CRLH) resonator and a defected ground structure is presented. The CRLH resonator resonates at the zeroth-order mode and acts as the first stage of the corresponding filter; an octagonal patch acts as a radiator as well as the last stage of the filter. The design procedure follows the circuit approach - synthesis of bandpass filters. The filtering antenna has two poles in the passband and two radiation nulls (zeros) at the band edges. Compared to the conventional patch antenna, the proposed filtering antenna, with little extra circuit area, has flat gain response within the passband, good selectivity at the passband edge and wider bandwidth. Measurement results show that the filtering antenna can operate at 5.29 GHz, has a 430 MHz bandwidth and a 2.5 dBi antenna gain in the broadside (+ Z ) direction within the passband.

A Compact Filtering Antenna With Flat Gain Response Within the Passband

A compact filtering antenna is designed for the modern wireless communication systems in this letter. First, a two-pole Butterworth bandpass filter is designed. Then, by substituting the second port and resonator with fan-shaped patch antenna (traditional antenna) with defected ground structure (DGS), a filtering antenna is formed. Compared to the traditional antenna, the filtering antenna obtains the flatter gain response within the passband, good selectivity at the passband edge, and the wider bandwidth. Measured results show that the filtering antenna can operate at 2.4 GHz and has a 460-MHz bandwidth and a 2.3-dBi peak gain within the passband. Moreover, a radiation zero occurs at 3 GHz.

A New Compact Filter-Antenna for Modern Wireless Communication Systems

Design, fabrication, and measurement of a new compact filter-antenna for modern wireless communication systems are presented in this letter. Two microstrip square open-loop resonators, a coupled line, and a Γ-shaped antenna are used and integrated to be a filter-antenna. The Γ-shaped antenna is excited by a coupled line that is treated as the admittance inverter in filter design. The Γ-shaped antenna performs not only a radiator, but also the last resonator of the bandpass filter. Therefore, near-zero transition loss is achieved between the filter and the antenna. The design procedure follows the circuit approach-synthesis of bandpass filters. Measured results show that the filter-antenna achieves an impedance bandwidth of 16.3% (over 2.26-2.66 GHz) at a reflection coefficient |S11 | <; - 10 dB and has a gain of 2.41 dBi.