Microstrip Leaky-Wave Antenna for Radar Applications

The work in this article focuses on developing and improving the performance of new leaky-wave antenna configurations that can be adapted for use in radar systems. The study focused on the W-band, where we demonstrated the possibility of modifying resonant frequencies and reducing the number of patches required. The antenna was designed using HFSS, based on the finite element method. It we designed enabled us to observe the influence of the number of patches on the radiation pattern, and also to achieve low levels of minor’s lobes. and good directivity at the operating frequency. These patches are arranged in the shape of an inverted T. The interest of this study is to meet the requirements of radar antennas dedicated to detection.

Designing a Dual-Feed Circular Polarization Antenna

This paper describes a novel dual-feed circularly polarized antenna,and the dual feeding mode is realized by grooving on the antenna radiator.The antenna utilizes air dielectric material to meet the requirements of low weight and cost.Test results demonstrate that the antenna exhibits capacitive loading between the metal antenna patch and the ground floor,allowing for adjustment of the working frequency of the dual-feed circularly polarized microstrip antenna.Specifically,the original center frequency of 2.264 GHz was reduced to 1.582 GHz,facilitating antenna miniaturization and broad bandwidth.With a return loss(S11)below-10 dB,a bandwidth of 72 MHz(1.552-1.624 GHz)was obtained.Additionally,the dual-feed microstrip antenna incorporates a 90°bridge,resulting in circular polarization gains of 2.26 dBi at 1.561 GHz and 2.45 dBi at 1.575 GHz.Overall,the antenna design offers a large working bandwidth and excellent circular polarization characteristics,making it suitable for a wide range of applications in satellite navigation and positioning terminals.

A Substrate Integrated Waveguide Based Filtenna for X and Ku Band Application

In this paper Substrate Integrated Waveguide-basedfiltenna operating at Ku band is proposed.The model is designed on a low loss dielectric substrate having a thickness of 0.508 mm and comprises of shorting vias along two edges of the substrate walls.To realize a bandpassfilter,secondary shorting vias are placed close to primary shorting vias.The dimension and position of the vias are carefully analyzed for Ku band frequencies.The model is fabricated on Roger RT/duroid 5880 and the performance characteristics are measured.The proposed model achieves significant impedance characteristics with wider bandwidth in the Ku band.The model also achieves a maximum gain of 7.46 dBi in the operating band thus making it suitable for Ku-band applications.Substrate Integrated Waveguide(SIW)Structures possess most of the advantages over conventional radiofrequency waveguides since they have high power management capacity with self-consistent electrical shielding.The most noteworthy advantage of SIW,it can able to integrate all the components on the same substrate,both passive and active components.

Higher Order OAM Mode Generation Using Wearable Antenna for 5G NR Bands

This paper presents a flexible and wearable textile array antenna designed to generate Orbital Angular Momentum(OAM)waves with Mode+2 at 3.5 GHz(3.4 to 3.6 GHz)of the sub-6 GHz fifth-generation(5G)New Radio(NR)band.The proposed antenna is based on a uniform circular array of eight microstrip patch antennas on a felt textile substrate.In contrast to previous works involving the use of rigid substrates to generate OAM waves,this work explored the use of flexible substrates to generate OAM waves for the first time.Other than that,the proposed antenna was simulated,analyzed,fabricated,and tested to confirm the generation of OAMMode+2.With the same design,OAM Mode−2 can be generated readily simply by mirror imaging the feed network.Note that the proposed antenna operated at the desired frequency of 3.5 GHz with an overall bandwidth of 400 MHz in free space.Moreover,mode purity analysis is carried out to verify the generation of OAM Mode+2,and the purity obtained was 41.78%at free space flat condition.Furthermore,the effect of antenna bending on the purity of the generated OAM mode is also investigated.Lastly,the influence of textile properties on OAM modes is examined to assist future researchers in choosing suitable fabrics to design flexible OAM-based antennas.After a comprehensive analysis considering different factors related to wearable applications,this paper demonstrates the feasibility of generating OAMwaves using textile antennas.Furthermore,as per the obtained Specific Absorption Rate(SAR),it is found that the proposed antenna is safe to be deployed.The findings of this work have a significant implication for body-centric communications.

Design of a High-Gain 2 × 1 Array Antenna for S-Band Applications

Antennas are an indispensable element in wireless networks. For long-distance wireless communication, antenna gains need to be very strong (highly directive) because the signal from the antenna loses a lot of strength as it travels over long distances. This is true in the military with missile, radar, and satellite systems, etc. Antenna arrays are commonly employed to focus electromagnetic waves in a certain direction that cannot be achieved perfectly with a single-element antenna. The goal of this study is to design a rectangular microstrip high-gain 2 × 1 array antenna using ADS Momentum. This microstrip patch array design makes use of the RT-DUROID 5880 as a substrate with a dielectric constant of 2.2, substrate height of 1.588 mm, and tangent loss of 0.001. To achieve efficient gain and return loss characteristics for the proposed array antenna, RT-Duroid is a good choice of dielectric material. The designed array antenna is made up of two rectangular patches, which have a resonance frequency of 3.3 GHz. These rectangular patches are excited by microstrip feed lines with 13 mm lengths and 4.8 mm widths. The impedance of the patches is perfectly matched by these transmission lines, which helps to get better antenna characteristics. At a resonance frequency of 3.3 GHz, the suggested antenna array has a directivity of 10.50 dB and a maximum gain of 9.90 dB in the S-band. The S parameters, 3D radiation pattern, directivity, gain, and efficiency of the constructed array antenna are all available in ADS Momentum.

Breast Cancer Detection Based on Multi-Slotted Patch Antenna at ISM Band

The present work designed and investigated a 3D basic model for breast cancer detection at the ISM band. The model consists of two multi-slotted rectangular patch antennas and a three-layer breast phantom containing two tumors. A multi-slotted antenna was designed at 2.45 GHz using CST STUDIO SUITE 2018, where the simulated results showed a return loss better than -35 dB and attended more than 77 MHz bandwidth. The diagnosis approach is based on exploiting the electrical properties (frequency dependent) of breast tissues, i.e., mass density, relative permittivity, and conductivity. Once the proposed slotted antenna radiates electromagnetic signals toward the breast model (with and without tumors), the radiation properties in terms of the scattering parameters (S11 and S21), the electrical field, the power flow, the current density, and the power loss density were altered. As a result, the values of these radiation parameters increased when tumors were implanted inside the breast model, informing the presence of cancerous tissues. Moreover, the specific absorption rate (SAR) was estimated as a function of input powers, where the proposed antenna showed a set of low SAR values compared to the IEEE standard of 1.6 W/kg, validating its potential use for diagnosing purposes. The simulated results indicated the prospective use of two slotted antennas (in the first instance) to detect multiple tumors which could be a challenging task using a single-element antenna, where the ultimate goal is to realize a compact antenna array to detect multi-tumors.

Breast Cancer Hyperthermia Treatment Based on Slotted Patch Antenna at 2.45 GHz

The present work proposed a simple model for breast cancer hyperthermia treatment at 2.45 GHz. The proposed model involves nine-element antennas alongside a numerical breast comprising multiple tumors. Using a coupled EM-Thermal simulation in the CST suite, the simulated results for a single antenna showed a reflection coefficient (S11) better than -47 dB and demonstrated a bandwidth of 78 MHz. The specific absorption rate (SAR) as a function of input powers was examined inside the breast tissues, where it exhibited a promising performance higher than 3 W/kg at the tumor volume when the applied power was at a reasonable level of 1.5 W whereas it was well attained under the recommend IEEE level of 1.6 W/kg through the surrounded health tissues. Taking into consideration nine-element antennas covering the breast containing two different located tumors, the maximum temperature as a function of treatment time was presented at which a resulting temperature of 43°C was obtainable within 10 minutes, favored for hyperthermia purposes. Considering the maximum power level of 1.5 W, the potential use of applying three-element antennas, simultaneously with 0.5 W, could be achieved.

Photocatalysis of TiO2 Sheets Prepared by Templating Filter Paper

Titanium dioxide sheet photocatalysts composed of interwoven microstrips were successfully synthesized using filter paper as templates. The synthesized samples were characterized by means of Fourier transform infrared spectroscopy, surface area analyzer, thermogravimetric analysis, powder X-ray diffraction, and scanning electron microscopy. The photocatalytic activities of the samples were evaluated by the degradation of methyl orange in an aqueous solution under UV-illumination. The results demonstrated that the paper-like TiO2 sheets with the optimum proportion of anatase/rutile （10/1） had the highest photoactivity. And the presence of the filter paper fiber can improve the crystallinity, raise the anatase-rutile transformation temperature and contribute to the formation of being paper-like. A detailed formation mechanism for TiO2 sheets is proposed.

MODIFIED ULTRA WIDEBAND CIRCULAR PRINTED MONOPOLE ANTENNA

A simple and compact microstrip-fed ultra wideband （UWB） printed monopole antenna is presented. The antenna is composed of a circular radiator and a finitely grounded plane. The antenna occupies about 16.62 GHz absolute bandwidth and 142.7% relative bandwidth covering from 3.38 GHz to 20 GHz with voltage standing wave ratio （VSWR） below two. A quasi-omnidirectional and quasi-symmetrical radiation pattern in H plane is obtained in the whole bandwidth. The high performance of the antenna is validated with measured and simulated results given. The antenna can be applied for the system design of UWB wireless communication.

Compact dual-band bandpass filter for WLAN systems

A novel dual-band planar microstrip filter using parallel coupled microstrip lines and open-loop stepped-impedance resonators（SIRs）loaded with two shunt open stubs is presented.By tuning the physical lengths of open-loop SIRs,parallel coupled microstrip lines and two stubs,the bandpass filter has good dual-passband performance at 2.55 and 5.35 GHz and high isolation between the two passbands.The relative bandwidths of the two passbands are 11.8% and 16.8%,respectively.Compared with the conventional open-loop SIR filters,the designed filter has a comparatively broader fractional bandwidth at the second passband.So it can cover all the wireless LAN（local area network）bands.In addition,the filter has the features of low loss,high rejection and low ripple.The measured results are in good agreement with the simulated responses by HFSS software.

Study of multi-band property of rectangular microstrip patch antenna having different numbers of wide slots

The property of multi-band operation has been studied and investigated analytically through the design of a rectangular patch microstrip antenna having different numbers of wide slots arranged at both the radiating edges. The analyses were carried out using the method of moments simulation software. It is shown that a patch with three slots has a multi-band feature with four resonant frequencies at 1.6, 1.8, 2.65, and 4.83 GHz and adequate values of return loss and gain. It is also shown that a patch with two pairs of wide slots arranged at both the radiating edges has the dual band feature with resonant frequencies at 1.64 and 1.8 GHz and good values of return loss and gain.

Dual-Polarized Slot-Coupled Microstrip Antenna with Very High Isolation

A wideband dual-polarized slot-coupled stacked microstrip antenna with very high isolation and low cross-polarization is presented. To improve isolation between two poiarization ports, the stacked patches are excited by an open-ended and a T-shaped microstrip lines both via two H-shaped slots placed in a ＂T＂ configuration. The measured isolation is better than 40.5 dB over the bandwidth from 8.8 to 9.8 GHz with cross-polarization level less than - 28.5 dB. The measured VSWR ≤ 2 bandwidths reach 20.7 96 and 19.196 at the verrical and horizontal polarization ports, respectively. This antenna is suitable to be used as array elements in spacebome synthetic aperture radars （SAR） and active phased array radars.

Metamaterials and metasurfaces for designing metadevices:Perfect absorbers and microstrip patch antennas

In the past twenty years, electromagnetic metamaterials represented by left-handed metamaterials（LHMs） have attracted considerable attention due to the unique properties such as negative refraction, perfect lens, and electromagnetic cloaks. In this paper, we present a comprehensive review of our group＇s work on metamaterials and metasurfaces. We present several types of LHMs and chiral metamaterials. As a two-dimensional equivalent of bulk three-dimensional metamaterials, metasurfaces have led to a myriad of devices due to the advantages of lower profile, lower losses, and simpler to fabricate than bulk three-dimensional metamaterials. We demonstrate the novel microwave metadevices based on metamaterials and metasurfaces： perfect absorbers and microwave patch antennas, including novel transmission line antennas,high gain resonant cavity antennas, wide scanning phased array antennas, and circularly polarized antennas.

A G-band terahertz monolithic integrated amplifier in 0.5-μm InP double heterojunction bipolar transistor technology

Design and characterization of a G-band（140–220 GHz） terahertz monolithic integrated circuit（TMIC） amplifier in eight-stage common-emitter topology are performed based on the 0.5-μm In Ga As/In P double heterojunction bipolar transistor（DHBT）. An inverted microstrip line is implemented to avoid a parasitic mode between the ground plane and the In P substrate. The on-wafer measurement results show that peak gains are 20 dB at 140 GHz and more than 15-dB gain at 140–190 GHz respectively. The saturation output powers are-2.688 dBm at 210 GHz and-2.88 dBm at 220 GHz,respectively. It is the first report on an amplifier operating at the G-band based on 0.5-μm InP DHBT technology. Compared with the hybrid integrated circuit of vacuum electronic devices, the monolithic integrated circuit has the advantage of reliability and consistency. This TMIC demonstrates the feasibility of the 0.5-μm InGaAs/InP DHBT amplifier in G-band frequencies applications.

Wireless Strain Measurement Based on a Microstrip Patch Antenna

Wireless interrogation of a rectangular microstrip patch antenna for strain measurement is investigated by simulations.To analyze the antenna performance,a microstrip line-feeding patch antenna at 10 GHz is designed.A patch antenna wirelessly fed by a horn is proposed to measure the strain.The direction information of strain detected by the patch antenna is also considered.The strain can be detected both in the width and length directions.It is shown that the strain can be measured wirelessly using a standard horn antenna.This kind of wireless strain-sensing technique offers significant potential for wireless structural health monitoring(SHM),especially for high-end equipment.

Strain-Insensitive Hierarchically Structured Stretchable Microstrip Antennas for Robust Wireless Communication

As the key component of wireless data transmission and powering,stretchable antennas play an indispensable role in flexible/stretchable electronics.However,they often suffer from frequency detuning upon mechanical deformations;thus,their applications are limited to wireless sensing with wireless transmission capabilities remaining elusive.Here,a hierarchically structured stretchable microstrip antenna with meshed patterns arranged in an arched shape showcases tunable resonance frequency upon deformations with improved overall stretchability.The almost unchanged resonance frequency during deformations enables robust on-body wireless communication and RF energy harvesting,whereas the rapid changing resonance frequency with deformations allows for wireless sensing.The proposed stretchable microstrip antenna was demonstrated to communicate wirelessly with a transmitter(input power of−3 dBm)efficiently(i.e.,the receiving power higher than−100 dBm over a distance of 100 m)on human bodies even upon 25%stretching.The flexibility in structural engineering combined with the coupled mechanical-electromagnetic simulations,provides a versatile engineering toolkit to design stretchable microstrip antennas and other potential wireless devices for stretchable electronics.

A BROADBAND APERTURE-COUPLED STACKED MICROSTRIP ANTENNA WITH BOTH PATCHES NOTCHED AND OFFSET

This paper proposes a new approach to further improving the bandwidth of a typical aperture-coupled stacked microstrip antenna by cutting triangular notches in the radiating sides of both radiating patches together with offsetting both patches. An antenna applying this new approach is designed,fabricated,and tested. The experimental antenna could achieve a measured impedance bandwidth of about 37.5% for the Voltage Standing Wave Ratio(VSWR) ≤ 2in X-band.

Composite metamaterial enabled excellent performance of microstrip antenna array

This paper reports that the split ring resonators and complementary split ring resonators are compounded to construct a novel compact composite metamaterial. The composite metamaterial exhibits a unique property of blocking electromagnetic wave propagating in two directions near the resonant frequency. An example of two-element microstrip antenna array demonstrates that the developed metamaterial enables array performance that is an improvement in comparison with the traditional one, including mutual coupling suppression of 9.07 dB, remarkable side lobe suppression and gain improvement of 2.14 dB. The mechanism of performance enhancement is analysed based on the electric field and Poynting vector distributions in array. The present work not only is a meaningful exploration of new type composite metamaterial design, but also opens up possibilities for extensive metamaterial applications to antenna engineer.

Analysis of equivalent antenna based on FDTD method

An equivalent microstrip antenna used in radio proximity fuse is presented.The design of this antenna is based on multilayer multipermittivity dielectric substrate which is analyzed by finite difference time domain(FDTD) method.Equivalent iterative formula is modified in the condition of cylindrical coordinate system.The mixed substrate which contains two kinds of media(one of them is air)takes the place of original single substrate.The results of equivalent antenna simulation show that the resonant frequency of equivalent antenna is similar to that of the original antenna.The validity of analysis can be validated by means of antenna resonant frequency formula.Two antennas have same radiation pattern and similar gain.This method can be used to reduce the weight of antenna,which is significant to the design of missile-borne antenna.

Wideband dual-polarized slot-coupled microstrip array for synthetic aperture radar application

An 8 × 1-element wideband dual-polarized slot-coupled microstrip antenna array with high isolation and low crosspolarization in X-band is presented. The array antenna offers an impedance bandwidth （VSWR≤2） of 23% and 21% for dual polarization ports, respectively. The measured isolation between two polarization ports is better than 35 dB and the measured cross-polarization level below -25 dB in the main beam over the operation frequency band of 9.35 GHz to 9.75 GHz. This array is well suitable for X-band SAR （synthetic aperture radar） antenna apphcation.