Modified H-shaped Microstrip Array Antennas for WiMAX Applications

One of important parameters in array antenna is radiation characteristic which can be satisfied by implementing several design techniques. In this paper, by utilizing differentially proximity-coupled feeding technique, a circular ring-shaped array antenna is designed with improved radiation pattern characteristics. The proposed array antenna consists of 20 circular ring-shaped antenna elements arranged in 4 $\times$ 5 array. Differentially proximity-coupled feeding technique applied for each antenna element is aimed to have symmetrical radiation pattern. The array antenna which is designed to work at the frequency of 1.275 GHz for L-band frequency application is implemented using two layers of FR4 epoxy dielectric substrate with the total dimension of 199.3 mm $\times$ 189.5 mm. The characterization result shows that the proposed array antenna has good impedance matching with the reflection coefficient $(S_{11})$ of −21.65 dB and −10 dB impedance bandwidth of 80 MHz (1.21 GHz to 1.29 GHz). Meanwhile, a symmetrical radiation pattern at $E-$ plane is achieved with the half power beamwidth (HPBW) of 43°.

A three by four element broadside X-band microstrip planar array centered at 7.5 GHz was designed for high gain, low sidelobes and good impedance matching. The design starts with simulation of single patch in Matlabreg followed by its optimization in advanced design system (ADS) Momentum for high gain. It was achieved by over sizing the patch dimensions and making it resonant at the same desired center frequency. A four element array of such patches was designed. Intra-element spacing and feed line dimensions were optimized for low sidelobes and impedance matching with transmitter. Then three such arrays were used to design a 3 times 4 element array. Inter-array spacing was optimized to achieve low sidelobes. The design was simulated and optimized in Momentum employing method of moments (MoM) to take into account the effect of mutual couplings of all the elements. The arrays were fabricated and tested in anechoic chamber. Microstrip power divider was used to feed the array by single source.

In this paper, we propose a novel wideband VHF antenna operating at central frequency of 200 MHz for impulse ground penetrating radar (GPR) systems. As operating at the low frequency, impulse GPR systems can work well at the depth to 5 m. The proposed bow-tie antenna has been created based on the Lemniscate curve. This structure helps the antenna achieve better performance than conventional bow-tie antennas. In the paper, we also propose a wideband balanced-to-unbalanced (balun) transformation line to feed our antenna. The balun has good performance and matching impedance. The antenna is implemented in FR4 substrate and copper patch. Based on design, simulation, and implementation results, it has been shown that our proposed antenna has a good matched impedance, stable radiation patterns, and constant gain. Thus, it can be thoroughly applied to GPR systems in the future.Keywordsground penetrating radar (GPR)wideband antennaLemniscate curvebow-tie antenna

In this brief, we present a low-loss mechanically reconfigurable phase shifter implemented in gap-waveguide technology for mm-wave frequencies. The proposed design gives a practical implementation of tuning elements inside the waveguide providing alternatives to the use of the E-plane split waveguide at high frequencies in order to avoid leakage losses. The depicted phase shifter design is based on a H-plane split waveguide. The phase shift is controlled by means of a tuning screw, which exerts pressure on a flexible metallic strip inserted inside the waveguide. The flexible strip bends with different curvature radii and determines the phase shift at the output port. Cost-effective manufacturing and simple implementation of the flexible metallic strip are achieved by means of the gap-waveguide design. A prototype has been manufactured for validation purposes. Good impedance matching is achieved from 64 GHz to 75 GHz providing a 15.8% impedance bandwidth. The results show a maximum phase shift of 250$^{o}$ with a maximum and mean insertion loss (IL) of 3 dB and 1.7 dB, respectively.

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This paper presents novel compact dipole antennas based on forward-coupling configuration of multilayer ring resonators (MRR) structure. The antenna consists of two conductive square open loops. The frequency of operation can be varied through the coupling between the two rings. This is achieved by changing the distance between the two radiating elements. Hence, these types of antennas are simply tunable. The structure is so versatile that a class of new antennas can be developed using this technique. The radiation pattern is bidirectional with a peak gain of 2.8 dBi. A good impedance matching and return loss better than 35 dB are obtained. Simulations have been carried out and the S-parameters, VSWR and radiation patterns are presented.

In this paper, a novel design for a triple-band coplanar waveguide (CPW)-fed monopole antenna for WLAN/WiMAX operations is proposed. The proposed antenna is printed on an FR4 substrate with an area of 22.0 mm × 30.0 mm, a thickness of 1.0 mm, and a relative permittivity of 4.4. The effects of various parameters of the proposed for triple band operation is investigated. Two half circular rings and a microstrip feed line are fabricated on the substrate to achieve triple band operation and good impedance matching. Prototypes of the proposed antenna have been fabricated and tested. Experiment results reveal that the measured return loss exhibits an acceptable agreement with the simulated return loss and satisfies the impedance bandwidth requirement of -10 dB, while simultaneously covering the WLAN and WiMAX bands. In addition, the proposed antenna shows good radiation characteristics and gains in the three operating bands.

In this work, a circularly-polarized ultra-high frequency (UHF) partial discharge (PD) antenna is proposed to detect the PD in 0.6 GHz - 1.7 GHz. The proposed PD antenna consists of an Archimedean spiral antenna, a balun, and a cavity. The Archimedean spiral antenna is embedded by FR-4 as substrate and superstrate for miniaturization. The microstrip-to-paired strips balun is designed to yield good performance in the return loss, insertion loss, and amplitude and phase imbalances which are of great necessity for low axial ratio. The cavity is employed to obtain unidirectional radiation patterns and prevent external signal interference. However, it is found that the originally-designed cavity-backed antenna does not work properly near 1.35 GHz due to resonance phenomena in the cavity. In this work, the cavity is modified to tackle this problem. The proposed UHF PD antenna is fabricated and measured and the results show that it provides good impedance matching, realized gain, radiation pattern, and circular polarization.

This paper presents a compact split ring resonator metamaterial-embedded rectangular microstrip patch antenna. The inset-fed rectangular microstrip patch antenna (RMPA) resonates at 5.29 GHz frequency with return loss −12.108 dB is designed with applications in wireless communication. After then, RMPA is embedded with metamaterial split ring resonator. This metamaterial structure gives reduced resonant frequency and improved bandwidth along with good impedance matching. This technique also provides 27% reduction in size of RMPA. The proposed antenna is simulated using HFSS software, the prototype antenna has been fabricated and results are measured.

This paper presents a printed and an integrated bi-directional tunable positive/negative refractive-index phase shifter utilizing CMOS tunable active inductors (TAIs). The printed phase shifter is comprised of a microstrip transmission line (TL), loaded with series varactors and a shunt monolithic microwave integrated circuit (MMIC) synthesizing the TAI. Using the TAI extends the phase tuning range and results in a low return loss across the entire tuning range. The integrated circuit (IC) phase shifter replaces the TLs with suitable lumped L-C sections. This enables integrating the entire phase shifter on a single MMIC, resulting in a compact implementation. The TAI used for both phase shifters is based on a modified gyrator-C architecture, employing a variable resistance to independently control the inductance and quality factor. The TAI is fabricated in the 0.13-mum CMOS process and operates from a 1.5-V supply. The TAI chip is used to implement the TL phase shifter, which achieves a phase of -40deg to +34deg at 2.5 GHz with less than -19-dB return loss from a single stage occupying 10.8 mm times 10.4 mm. The IC phase shifter is fabricated in the same process and achieves a phase from -35deg to +59deg at 2.6 GHz with less than -19-dB return loss from a single stage occupying 550 mum times 1300 mum.

Notice of Violation of IEEE Publication Principles<br><br>"Both the authors and the Editor-in-Chief of Volume 13, number 3 of the IEEE/ASME JMEMS (June 2004, pp. 542-549) of the paper numbered JMEMS 1041 have agreed that this paper, Ka-Band Distributed MEMS Phase Shifters on Silicon Using AlSi Suspended Membrane," should not have been published. The paper would have been withdrawn had this fact been discovered before the IEEE/ASME JMEMS print date for June 2004. The authors have indicated that they will work to provide a new version their paper that will be considered for publication if it is submitted in the future. For help in coming to this decision, I would like to thank those concerned individuals, including the authors, JMEMS editors, and highly respected researchers in the MEMS and microwave communities who contributed their time and consideration to help us assure the integrity of our journal." <br><br>Richard S. Muller, Editor-in-Chief, IEEE/ASME JMEMS<br><br>This paper presents the design, fabrication, and testing of distributed MEMS phase shifters for Ka-band communication systems. The phase shift can be obtained by changing MEMS bridge capacitors located periodically over the transmission line. Simulation results of phase shifters with various structural parameters are analyzed to develop the optimized designs. The phase shifters are fabricated on the high-resistivity silicon substrate, using suspended AlSi bridge membrane. The measured results demonstrate a phase shift of 286° at 36 GHz with the actuation voltage of 25 V, and a return loss better than 10 dB over 0-40 GHz band. In addition, lifetimes of 3×10/sup 6/ cycles have been achieved for the fabricated phase shifter with all MEMS bridges held to be valid. It shows that AlSi alloy has a nice compromise between strength and resilience. <br/> This paper presents the design, fabrication, and testing of distributed MEMS phase shifters for Ka-band communication systems. The phase shift can be obtained by changing MEMS bridge capacitors located periodically over the transmission line. Simulation results of phase shifters with various structural parameters are analyzed to develop the optimized designs. The phase shifters are fabricated on the high-resistivity silicon substrate, using suspended AlSi bridge membrane. The measured results demonstrate a phase shift of 286° at 36 GHz with the actuation voltage of 25 V, and a return loss better than 10 dB over 0–40 GHz band. In addition, lifetimes of 3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> cycles have been achieved for the fabricated phase shifter with all MEMS bridges held to be valid. It shows that AlSi alloy has a nice compromise between strength and resilience.

Investigation of adjacent spacing dependent microwave absorption properties of lamellar structural Ti3C2Tx MXenes

Chapter 11 - Phase Shifters

In this paper, we designed a rectangular patch single and array antenna by using CST software version 18.0. First, we used a copper as radiating patch and then the nanomaterial conductor like carbon nanotube (CNT) to improve the antenna performance. In both cases, the operating frequency is 2.4 GHz, which is used for many communication applications including Wi-Fi and Bluetooth. We have designed the four-element patch array antenna in two forms of arrangement (series and corporate feed). We used the substrate FR4 (its height=1.6 mm, Єr=4.3) and copper as the ground in all our designs. The return loss (s parameter) Always less than 10 dB the value of voltage standing wave ratio (VSWR) was close to the one in the designs. The highest directivity obtained from a patch array (1×4) antenna was 13.5 dBi when using carbon nanotube. Finally, we made a comparison of the analyzed results after simulation in a detailed table of the basic antenna properties, Including Return loss, VSWR, gain and directivity at the resonant frequency.

Nowadays in Indonesia, 3D Radar has been developed to perform a vertical scanning that has multi-functional benefits in telecommunication industry and defence. As a common practice, 3D radar system is frequently used to measure the distance of an object like the aircraft. Therefore, the most important element in radar systems is the phase shifter that has a main role in steering the beam and replacing the rotator function. This final research will focus on the operation of simple Phase Shifter with concerning a 2,9 GHz – 3,1 GHz radar frequency. Phase shifter designed at 3 GHz as the centre frequency within a value return loss ≤ -15 dB, insertion ≥ -4 dB, coupling ≥ -4 dB, isolation ≤ -15 dB, phase difference 45°, 90°, 135°, phase error ≤ 15°, and realized by converting into Microstrip Quadrature Hybrid Coupler 90°. These particular phase shifter uses the type of substrate Rogers R04035B with dielectric constant values (εr) at 3,48, and the thickness of the substrate ( h ) of 1,524 mm. Simulations are performed using Computer System Technology ( CST ) software suite 2015 and assigned the average results each port to return loss value -37,290519 dB, insertion -3,154242 dB, coupling -3,164594 dB, isolation -32,714140 dB, with phase difference 45,00816°, 89,09566°, 90,76276°, 134,85057° and phase error 0,00816°, 0,90434°, 0,76276°, 0,14943°, It is then subsequently realized and measured by Netwotk Analyzer and return loss -30,078370 dB, insertion -3,229792 dB, coupling -3,146129 dB, isolation -42,651590 dB, phase difference 45,15190°, 86,38080°, 93,38538°, 134,36260° and phase error 0,15190°, 3,61920°, 3,38538°, 0,63740°.