Bandwidth and gain improvements of low‐profile H‐shaped microstrip patch antenna under quadruple‐mode resonance

A wideband low profile H‐shaped microstrip patch antenna (MPA) with reallocated quadruple‐mode resonance is presented for indoor wireless communication application. In this paper, the TM₂₀ (mode 1), TM₀₂ (mode 2), TM₂₂ (mode 3), and additionally notch mode 4 of the proposed MPA are simultaneously employed. First, the rectangular radiating patch is reshaped as an H‐shaped radiator so as to separate a pair of degenerate modes (mode 1 and mode 2). Then, a pair of linear notches is cut on the diagonal of the patch to excite an additional notch resonance (mode 4). Finally, in order to improve the frequency of mode 1, four shorting pins are placed at the four corners of the H‐shaped patch. Therefore, the bandwidth of the antenna is dramatically increased up by utilizing four resonant modes (modes 1, 2, 3, and 4). A prototype of H‐shaped patch antenna with notches and shorting pins is manufactured and measured. The results show that the antenna achieves a broad bandwidth of about 31.7% (2.31‐3.18 GHz), and its profile is only 0.036 wavelength of center frequency. It is particularly noticed that a relative high gain of around 9.8 dBi is successfully acquired, while keeping relative stable dual‐beam radiation patterns.     

A multi‐mode wideband omnidirectional monopolar patch antenna for indoor wireless communication systems

A wideband omnidirectional monopolar patch antenna merged multi‐mode with a simple structure is proposed in this article. The antenna consists of a circular patch and a concentric annular ring, which is coupled‐fed by a T‐shape monopole at its center. A wideband performance is achieved by converging multi‐mode: TM₀₂ mode of the circular patch, TM₀₂ mode of the annular ring and monopole mode of the T‐shape monopole. The measured results show that the proposed antenna has an impedance bandwidth of 55.3% from 4.45GHz to 7.85GHz. All of the three resonant modes lead to conical radiation patterns in the elevation plane and omnidirectional radiation patterns in the azimuth plane, and the measured peak gain varies from 6.1 to 10 dBi within the operating band, which verifies it can be a good choice for indoor wireless communication systems.     

High isolation dual‐frequency patch antenna integrated with cascade defected microstrip structure

This article presents a high‐isolation dual‐frequency rectangular patch antenna utilizing microstrip feed line integrated with a cascade defected microstrip structure (CDMS). Two types of CDMS are added, T‐shaped CDMS and Dumbbell‐T‐shaped CDMS. Simulation results show using these structures improve isolation up to 70 dB and reduce harmonic signals from transmitter. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

Generalized design approach to compact wideband multi‐resonant patch antennas

In this work, a generalized design approach to compact, wideband multi‐resonant microstrip patch antenna is proposed. Theoretical criterion of the length of the prototype dipole is laid down based on the simplest dipole model and the associated eigenmodes at first. Then, the criterion is employed to reveal the general relationship between the prototype dipole length, operational modes, sizes, and radiation behaviors of the resultant multi‐resonant circular sector patch antennas. Next, a compact wideband, dual‐resonant circular sector patch antenna is designed accordingly. It is operating at the TM_3/4,1 and TM_9/4,1 modes within a 240° circular sector patch radiator with its radii short circuited. The antenna fabricated on a single‐layered air substrate exhibits an available radiation bandwidth of 25.0%, with a profile as small as 0.043 guided wavelength at the center frequency. It is evidently verified that the approach can be employed to realize compact, dual‐resonant wideband microstrip patch antennas without increasing antenna profile, inquiring multiple radiators or employing reactance compensation techniques. In addition, it may lead to a series of novel wideband patch antenna designs with diverse performances.     

An off‐center‐fed compact wideband antenna with truncated corners and parasitic patches for circular polarization

A novel single‐fed circularly polarized wideband, compact and lightweight microstrip patch antenna (MPA) is proposed. The antenna is designed in a simple two‐phase procedure to achieve wideband and circular polarization. In the first phase, an off‐centered L‐shaped feeding arrangement is employed to obtain wideband (|S₁₁| < ?10 dB) over 10.6 GHz to 14.7 GHz with an improved peak gain of 5.25 dBi. In the second phase, the radiating patch is symmetrically truncated and two modified‐parasitic patches are added to ensure <3 dB axial ratio over 11.4 GHz to 12.8 GHz. A prototype has been fabricated and the measured results show close agreement with the simulation. The proposed antenna is suitable for fixed satellite and broadcast satellite communication in Ku‐band range.     

Design of dual‐band microstrip patch antenna with right‐angle triangular aperture slot for energy transfer application

This work focusing on the dual‐band antenna design with rectifying circuit for energy transfer system technology for enhancement gain performance. The air gap technique is applied on this microstrip antenna design work to enhance the antenna gain. The work begins with designing and analyzing the antenna via the CST Microwave Studio software. After validation on acceptable performance in simulation side is obtained, the return loss, S₁₁ of the antenna is measured using vector network analyzer equipment. The rectifier circuit is used to convert the captured signal to DC voltage. This projected dual‐band antenna has successfully accomplished the target on return loss of ?44.707 dB and ?32.163 dB at dual resonant frequencies for 1.8 GHz and 2.4 GHz, respectively. This proposed antenna design benefits in low cost fabrication and has achieved high gain of 6.31 dBi and 7.82 dBi for dual‐band functioning frequencies.     

A dual‐band dual‐mode microstrip Yagi antenna with quasi‐end‐fire radiation

A dual‐band dual‐mode microstrip Yagi antenna with quasi‐end‐fire radiation patterns is proposed in this paper. It consists of five radiating patches driven by a single slot‐loaded patch placed in the middle. Meanwhile, two slot‐loaded parasitic patches are symmetrically located on two sides of the driven patch, respectively. In the lower band, the five patches involved resonate at TM₀₁ mode. While in the upper band, all the patches resonate at TM₀₂ mode. In order to ensure quasi‐end‐fire radiations in the both bands, four slots are symmetrically etched around the strongest surface currents of each patch resonating at TM₀₂ mode. As a result, the resonant frequency of TM₀₂ mode is decreased dramatically, while the resonant frequency of TM₀₁ mode almost remains unchanged. With these arrangements, the separations between any two of the adjacent patches at their centers satisfy the requirements in design of the microstrip Yagi antenna in both bands, so as to realize the dual‐band dual‐mode microstrip Yagi antenna on a single‐layer substrate. Finally, an antenna prototype is fabricated and tested. The measured results reveal that the dual operating bands of 2.76~2.88 and 4.88~5.03 GHz for |S₁₁| < ?10 dB are satisfactorily achieved. Most importantly, the proposed antenna can indeed realize the quasi‐end‐fire radiation patterns in dual operating bands.     

A compact dual‐band zeroth‐order resonator antenna loaded with meander line inductor

A novel zeroth‐order resonator (ZOR) meta‐material (MTM) antenna with dual‐band is suggested using compound right/left handed transmission line as MTM. In this article, suggested antenna consists of patch through series gap, two meander line inductors, and two circular stubs. The MTM antenna is compact in size which shows dual‐band properties with first band centered at 2.47 GHz (2.05‐2.89 GHz) and second band is centered at 5.9 GHz (3.70‐8.10 GHz) with impedance bandwidth of (S₁₁ < ? 10 dB) 34.69% and 72.45%, respectively. At ZOR mode (2.35 GHz), the suggested antenna has overall dimension of 0.197λ_o × 0.07λ_o × 0.011λ_o with gain of 1.65 dB for ZOR band and 3.35 dB for first positive order resonator band which covers the applications like Bluetooth (2.4 GHZ), TV/Radio/Data (3.700‐6.425 GHz), WLAN (5‐5.16 GHz), C band frequencies (5.15‐5.35, 5.47‐5.725, or 5.725‐5.875 GHz) and satellite communication (7.25‐7.9 GHz). The radiation patterns of suggested structure are steady during the operating band for which sample antenna has been fabricated and confirmed experimentally. It exhibits novel omnidirectional radiation characteristics in phi = 0° plane with lower cross‐polarization values.     

Miniaturization and bandwidth enhancement of a cavity backed circular microstrip patch antenna

The resonant frequency of a circular patch antenna with and without circular cavity is measured. The patch miniaturization in the presence of the cavity is proved. Different methods of reducing resonant frequencies and broadening bandwidth without significantly reducing antenna gain are presented. Capacitively loaded patch and slits on the patch stimulate the patch at lower frequencies and multiple resonances, thus help miniaturization. Finally ferrite loading on the feed probe further increases the bandwidth without significantly reducing the antenna gain. The method is much more improved than that for a resistive loaded patch and a deformed patch. © 2007 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2007.     

A novel dual‐mode patch antenna with pattern diversity and beam‐tilting for aircraft applications

A dual‐mode patch antenna with pattern diversity that is beam‐tilted in a specific direction is presented. By placing a rectangular metal cavity below the circular patch and simultaneously shorting one end of the patch, the antenna produces tilted beams for dual‐mode radiation patterns. One pattern is excited using a proximity‐fed L‐shaped probe that generates a beam with a tilt angle of 25° from the broadside direction. The second pattern is excited using a coplanar waveguide (CPW)‐based feeding network that generates two beams with a tilt angle of θ_max = ±45° in the directions of ?_max = 70° and ? 70°. The tilt angle can be varied by adjusting the metal cavity's length. A prototype antenna for operation at 2.38 GHz was fabricated and measured. The results indicate that the overlapped bandwidth (|S₁₁| < ?10 dB) for the two patterns is 330 MHz (2.22‐2.55 GHz). The measured peak gains for the two patterns are 6.74‐6.94 dBi and 5.82‐6.74 dBi, respectively. The isolation between the two ports is 18 dB.     

Miniaturization and dual‐banding of an elevated slotted patch antenna using the novel dual‐reverse‐arrow fractal

A novel fractal geometry called dual‐reverse‐arrow fractal (DRAF) is introduced and compared with various versions of Koch fractals for application to triangular patch antennas. It is shown that DRAF results in the reduction of antenna size and tends to maintain its bandwidth. The presented DRAF is applied for the reduction of size of an elevated triangular patch antenna for the dual band operation in WLAN. This DRAF antenna has achieved 40% size reduction compared to a simple triangular patch antenna. For the provision of required bandwidth in the second frequency band (4.9‐5.9 GHz), a stepped U‐shaped slot is cut in the triangular patch. This antenna is more compact than similar antennas reported in the literature but maintains its fractional bandwidth (%25). The optimized design of the proposed DRAF antenna with air gap and slot is fabricated and tested, which verifies its expected specifications.     

Multiband reduced‐size patch antenna by employing a modified DMS‐spur‐line combo technique

In this article, a simple but effective combination of DMS and spur‐lines is achieved to obtain a multiband patch antenna. The advantage of this technique is the simplicity to elaborate and the good performance compared to other methods where nulls are present in the radiation pattern at the main lobe. The antenna presents five resonant frequencies, which are fully controllable by modifying the dimensions of the defected microstrip structures and spur‐lines, obtaining the characteristic directive radiation pattern and maximum gain above 6 dBi in all bands.     

A new compact dual‐wideband printed monopole antenna for WLAN/WiMAX applications

A new compact printed monopole antenna with dual‐wideband characteristics is presented for simultaneously satisfying wireless local area network and worldwide interoperability for microwave access applications. The antenna structure consists of a circular monopole with a microstrip feed‐line for excitation and a hexagon conductor‐backed parasitic plane. The antenna has a small size of 13 mm × 26 mm × 1 mm. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2011.     

A TM03 mode reduced side lobe high‐gain printed antenna array in K band for UDN and IoT applications in 5G

A single layer simple feed reduced side lobe gain‐enhanced microstrip antenna array using higher‐order modes is analyzed and designed in this work. The relationship between the relative magnitude of equivalent magnetic currents and directivity are studied. Modal analysis for rectangular patch is considered for broadside and non‐broadside radiation. Comparative investigations on antenna radiation and impedance characteristics for fundamental and higher‐order modes are presented. It is observed that an array can be designed to operate in TM₀₃ mode for enhanced gain with broadside radiation. Parametric optimization is carried out to attain low side lobe level. The proposed theory is validated by designing and fabricating a single layer single feed 2 × 2 microstrip patch array in the K band operating in TM₀₃ mode. The simulated and measured realized gain of the fabricated TM₀₃ mode array is 16.1 and 15.5 dBi, respectively, at 22 GHz with consistent broadside radiation pattern and linear polarization.     

A substrate integrated cavity‐fed dual‐polarized filtering patch antenna with high isolation

This article presents a dual‐polarized filtering patch antenna, which uses two orthogonal modes (TE₂₁₀/TE₁₂₀) of the substrate integrated cavity (SIC) to couple with two orthogonal modes (TM₁₀/TM₀₁) of the patch by the cross slot, respectively. The second‐order filtering response on dual polarizations can be achieved by using just one SIC resonator and one slotted square patch, which display simple structure of the proposed antenna. The slotted square patch provides a new way to obtain same external quality factor of the radiator on dual polarization, which makes the performances on two polarizations agree well with each other when changing the bandwidth. High isolation can be achieved by controlling the space of the vias of the SIC. Radiation nulls can be produced by connecting the coupled lines with the feeding lines in parallel. A prototype with the entire height of 0.019 λ₀ (λ₀ is the free‐space wavelength at center frequency) achieves a 10‐dB bandwidth of 1.6%, the gain of 4.9 dBi at the center frequency, the port isolation of 43 dB, and the out‐of‐band rejection level of 25 dB.     

Multisegment microstrip patch antenna with Y‐shaped feed

A new antenna structure comprising of multiple radiating microstrip patches, representing a figure of digit eight, proximity fed by a microstrip line is proposed. On a double‐layered substrate of FR4, this antenna achieves multiband functionality in the range of 3.81–12.42 GHz, which covers IEEE 802.11a standards and is suggestive of reconfigurability in frequency and pattern. Details of the antenna design, measured and simulation results are presented. © 2011 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2011.     

An UWB trapezoidal rings fractal monopole antenna with dual‐notch characteristics

An ultra‐wideband planar fractal monopole antenna with dual‐notch characteristics is presented in this article. The microstrip fed antenna consists of nested trapezoidal rings and defected ground plane. Measured results show that the proposed antenna operates with a 10 dB return loss bandwidth from 2.2 to 10.8 GHz with notch bands at (2500‐2690) MHz and (3300‐4200) MHz covering LTE 2500, WiMAX and part of C‐band.     

A compact dual‐band filtering antenna for wireless local area network applications

A printed dual‐band filtering antenna with decent frequency selectivity at 2.45 and 5.2 GHz for wireless local area network (WLAN) applications is developed. The filtering antenna is compact, which comprises a tapped feed line, two dual‐band stub‐loaded open‐loop resonators, and a dual‐band bended monopole. It can be easily printed on a single layer PCB substrate with low profile and low cost. The entire structure is very simple compared with the previously reported dual‐band filtering antennas that requiring multi‐layer structures. The monopole functions as not only a radiator, but also the last resonator of a dual‐band filter. The developed antenna exhibits good frequency selectivity and out‐of‐band suppression. In addition, the two operation bands can be adjusted relatively individually. The proposed antenna is optimized and fabricated. The experimental results show it has good frequency selectivity at both 2.45 and 5.2 GHz, wide bandwidth 11.8% and 7.8%, and excellent out‐of‐band suppression.     

A low‐profile wideband dual‐polarization patch antenna with antisymmetric feeding network

In this paper, a novel broadband dual‐polarization patch antenna is proposed. Antisymmetric Γ feeding network is applied to excite the radiating patch etched on the upper side of the horizontal substrate, which could minimize the undesired radiation from the probe and extend the impedance bandwidth. For verifying the proposed approach, a prototype is fabricated and measured, the simulated and measured results show the antenna has a wide impedance bandwidth of 48% (1.66‐2.71 GHz) for S11 < ?10 dB, as well as stable radiation gain around 9.5 dBi with low cross‐polarization. In addition, the total height of the antenna is only 0.17 λ₀ ( λ₀ is the free space wavelength of central frequency) and high port‐to‐port isolation is better than 30 dB. The characteristics of the proposed antenna illustrate it can be an indication for a micro base station in the mobile communication system.     

Design of a compact dense dielectric patch antenna based on half‐cut technique

In this article, a half‐cut rectangular dense dielectric patch (DDP) with one grounded side plane is theoretically investigated for designing a compact low‐profile antenna. According to the properties and the E‐field distribution of the dominant TM₁₀₁ mode, the half‐wavelength (λ/2) DDP can be bisected by effectively shorting the center plane to the ground, resulting in a miniaturized half‐cut λ/4 DDP. The size of the DDP is effectively reduced by 50% while maintaining the original resonant frequency of the dominant TM₁₀₁ mode. The half‐cut λ/4 DDP can be well excited through aperture coupling for antenna design. The design procedure of the proposed antenna is given in detail. For demonstration, an antenna prototype centered at 4.15 GHz is implemented and measured. The simulated and measured results are given, showing good agreement.