In this paper, a novel substrate integrated waveguide (SIW) to substrate integrated coaxial line (SICL) transition using the 3 dB SIW power divider (PD) and SIW 180° phase shifter (PS) is proposed. The SIW-to-SICL transition realizes the easy integration of SIW, SICL, and active device in the same microwave communication system based on the substrate-integrated technology (SIT). To validate the design concept, the prototype has been fabricated and measured. Measurements are in good agreement with simulations, and shows that the SIW-to-SICL transition features ultra-low insertion loss lower than 0.25 dB and with a fractional bandwidth over 10%.
Dual-mode square patch resonator is well known in the design of a single band quasi-elliptic bandpass filter response. Here, the dual-mode square patch resonator is employed to achieve a dualband bandpass filter. A 6 pole dual-band bandpass filter response with 3 poles at each passband will be presented. The dual-band filter also exhibits a transmission zero between the two passbands. A detailed discussion on the design procedure together with the simulation and experimental results will be presented.
A new design of a compact circularly polarized shorted annular stacked patch antenna has been introduced for Global Navigation Satellite System (GNSS) in this paper. The wideband characteristic is achieved by employing L-probe coupled feeding structure. The antenna is fed by four-output-ports strip line feeding network composed of three normal Wilkinson power dividers. As a result, the designed antenna has an effective bandwidth of 94.3% from 0.7 GHz to 1.95 GHz for VSWR< 2, and 57.1% 3-dB axial ratio bandwidth from 1.0 GHz to 1.8 GHz, respectively. The designed antenna has a compact size of 100 mm×100 mm×13 mm. The final antenna provides very good circularly polarized radiation for GNSS including GPS, GLONASS, Galileo and Compass.
A novel half Hemispherical Dielectric Resonator Antenna (HDRA) with an array of slots has been designed. The dielectric material used is Rogers TMM10, which is a ceramic thermoset polymer composite material having a dielectric constant of εr = 9.2. Periodic holes lower down the Q factor of the antenna and hence enhance the impedance bandwidth. The measured value of the 10 dB bandwidth is close to 1 GHz (~17.74%). The mode investigated is a TM101 like mode. Further, the effect of increasing the probe length on the resonance and the radiation pattern is also studied. As the probe length is increased, a shift in the resonant frequency is observed and the Dielectric Resonator Antenna (DRA) behaves as a monopole antenna loaded with the DRA. The experimental results confirm that a wide bandwidth of 1.3 GHz (~29%) with a high gain of 7.2 dBi can be obtained. The radiation pattern of such an antenna is directive in nature.
This paper presents results from an indoor LOS channel measurement campaign at the 60 GHz band. The results include the Ricean K-factor and time dispersion/frequency selectivity, which dominate the data-rate and error-performance limitations of the channel. Finally, three clusters are identified and the well known Saleh-Valenzuela model is used to statistically describe the interarrival times and the power decay of clusters and multipath components in the clusters.
A new design of a wideband Wilkinson power divider using double-sided parallel strip line technique is presented in this paper. To obtain a good isolation value, the proposed design was integrated with three isolation resistors. The proposed power divider is designed for a wide range of frequencies between 2 GHz to 6 GHz with all the ports matched to 50 Ω. The conventional quarter wavelength arms are divided to three different widths to ensure wideband capabilities. Moreover, the novelty of the proposed design come from the double-sided parallel-strip line technique where proposed design is using similar structure at both the top and bottom layers to ensure balance of transmission. All dimensions for the transmission line section were optimized to achieve wideband operation and were integrated with a lumped element. This design can be used as a double-sided feeder for a microstrip antenna.
This paper presents analysis results relative to an underground MIMO channel. Measurement campaigns were conducted in a former gold mine at a center frequency of 5.8 GHz under Line-Of-Sight (LOS) scenario. Extracted data have been processed to obtain the relevant statistical parameters of the channel. The resulting propagation behavior differs from frequently encountered in more typical indoor environments, such as offices and corridors. Indeed, the path loss exponent is less than 2 in MIMO configuration due to the large number of scatters that increase the received power when compared to the free-space case. Moreover, there has been a significant increase in spectral efficiency, when using MIMO technique. Hence, according to calculated statistical parameters, wireless link performance is improved through the use of the MIMO scheme. All in all, multi antenna systems present an ideal alternative for future underground communication systems.
In this paper, a modified Wilkinson power divider structure with three order harmonics suppression is presented. The quarter-wavelength microstrip lines in the traditional Wilkinson power divider (WPD) are replaced by two transmission line segments with ends connected (TTLWEC). The TTLWEC performs the functions of impedance transformation and three order harmonics suppression. The design equations are deduced by odd- and even-mode theory. An example of power divider operating at 1 GHz is designed and fabricated based on the printed circuit board technology. The measured results of 3.13 dB insert loss (IL) and 35 dB return loss (RL) are obtained at the operating frequency, and the first, second and third harmonic harmonics suppressions are -38 dB, -44 dB and -39 dB, respectively, which agree well with the simulated results and validate the availability of the proposed structure.
In this paper we develop a small-sized mode converter with high performance, high conversion efficiency and instantaneous bandwidth as high as 55%. This mode converter transforms energy from the TM01 first high-order mode towards the fundamental TE11 circular waveguide mode. The proposed structure increases the free spurious operating bandwidth in comparison with the existing results in literature. An X/Ku-bands experiment prototype unit was designed, ensuring practical return losses better than 28 dB and insertion losses less than 0.1 dB (conversion efficiency > 98.8%) within the entire frequency bandwidth ranging from 9.25 GHz to 16.25 GHz. The presented architecture offers useful features such as very wide bandwidth, small size, easy achievement as well as excellent performance, which makes it very suitable for High-power microwave (HPM) sources that generate the TM01 circular waveguide mode. In these cases the TE11 mode is needed since it has a convergent radiation pattern able to drive conventional antennas. Moreover, this compact concept is fully scalable to any millimeter frequency band.
A novel method for tapered rectangular dielectric rod antenna design is presented. This method can be used to design from millimetre to terahertz antennas. The work modes of antenna have been analyzed. The input modes are fundamental mode and second mode, and the end-fire mode is only fundamental mode. The calculation formulas for bottom diameter and top diameter are given according to the work modes. In order to avoid standing wave in the antenna, the wave will not reflect on the boundary surface of antenna. The calculation formula of antenna length is given based on the radial theory. Different shaped 300 GHz antennas have been designed based on the method. The results indicate that this method is suitable for different shapes of rectangular rod antennas. We also give the other two 1 THz and 32 GHz antenna design to demonstrate this method. The antenna gain will increase with the length expanding based on our design. The bottom and top diameters can be tuned slightly because the work mode formulas of rectangular dielectric waveguide are derived approximately. As an example different tuning designs of 100 GHz indicate that the tuning region is based on the calculation results. The design results have ultra wide bandwidth which is almost 50% of center frequency and high gain.
Two 2-D natural fractal monopoles generated by electro-deposition are characterized in term of measured return loss. Depending on their different shapes, previously reported multi-band behaviour and new ultra-wideband (UWB) characteristics are obtained. Finally, sufficient efficiencies are measured for both antennas proving their possible use as radiating element.
This article presents the coplanar capacitive coupled probe fed microstrip antennas for dual frequency band operation. The proposed antenna is excited by a single probe feed connected to a capacitive strip. Of the two dual band antennas presented here, the first one uses small air gap and the other is designed without air gap. In the first case an effort has been made to reduce the height of suspended antenna. A vertical slot is placed to obtain antenna resonance at low frequency side, and also for proper impedance matching. After presenting the basic geometry the second configuration (which uses no air gap) which also offers dual band operation at the expense of reduced bandwidth is presented. Measured values fairly agree with the simulated results.
A switchable microstrip patch antenna for multi-frequency operation is presented. The antenna is fed by a coplanar waveguide via capacitive coupling slot. The antenna allows easy reconfigurability of the frequency band of operation by incorporating switches in the coupling slot. The resonant frequency of the antenna can be adjusted by setting the switches on or off. Two prototypes are presented. The first incorporates two PIN diodes and capable of switching between four frequency bands, over a frequency range of 1.23:1. The second prototype incorporates four PIN diodes and is capable of switching between sixteen frequency bands, over a frequency range of 1.5:1. The structure has a compact and simple biasing circuit. Simulation and measurement indicate that the proposed antennas demonstrate very good impedance matching, stable radiation patterns and good gain at all frequency bands.
In this paper, a novel high selectivity dual-band microwave bandpass filter (BPF) using dual-mode and triple-mode resonator is proposed. First, a dual-band filter comprising two dual-mode single band filters using common input/out lines is designed. Each single BPF is realized using a stepped-impedance resonator (SIR) with a centrally-loaded shunt open stub. The first and second passband can be independently controlled by the two dual-mode resonators, respectively. The proposed filter also offers three transmission zeros (TZs) to improve the selectivity. To further improve the selectivity over high side band of the first passband, a novel triple-mode resonator is designed to replace the dual-mode resonator. The basic structure of triple-mode resonator is microstrip-to-coplanar waveguide (CPW) structure. The microstrip structure provides one odd mode and one even mode resonator frequency and the CPW structure can provide another even mode resonant frequency without increasing circuit size. Both simulated and measured results show that the filters exhibit a good performance, including a small insertion loss, selectivity.
A unique-planar vialess Marchand balun for V-band application is presented. The balun can achieve less than 2° phase imbalance and 0.3 dB amplitude imbalance from 54 GHz to 66 GHz, with the insertion losses of -3.6 dB and -3.9 dB for the two balanced ports and the return loss of unbalanced port of less than -15 dB in the unbalanced port. The novel back-to-back measured method has been proposed and analyzed, the amplitude and phase imbalances can be derived from the measured back-to-back two-port scattering results. The extracted results achieve good agreement with the single balun simulation, no more than 0.15 dB and 1° amplitude and phase differences. This balun configuration and the measurement method can simplify the fabrication, achieve good yield, ease the assembling and decrease the cost.
A novel cross-coupled resonator filter with multilayer structure is presented in this paper. By using enhanced inner coupling structure and 3D layout, the resonator size is largely reduced, and high spurious frequency could be achieved. To validate the proposed topology, a cross-coupled 3D filter with inner coupling capacitor is easily fabricated on a normal printed circuit board. The measured results show the characteristics of small size, good stopband performance and high spurious frequency.
The intermittent sampling repeater jamming (ISRJ) can only produce fake point scatterers in the down-range, while the time-varying frequency induced by rotational micro-motion dynamics blurs the image in the cross-range. This paper focuses on the combination of the above two methods to counter the inverse synthetic aperture radar (ISAR). Based on the signal models of coherent ISAR signal processing, principles of the jamming are derived. The key jamming parameters and the selection criteria are determined by two steps. Finally, the validity of the proposed algorithm is demonstrated using the numeric simulations and simulations based on the measured data.
Novel dual-band 90° couplers with arbitrary power division ratios using simplified composite right-/left-handed (SCRLH) transmission lines (TLs) are proposed. With a degree of freedom in the structural parameters, a SCRLH stub can easily be tailored to imitate a conventional 90° section at two arbitrary frequencies with different characteristic impedances, making the resulting couplers with customizable power division ratios, as well as ensuring the size miniaturization and element realizability. To validate our idea, 90° couplers operated at 2.45/5.2 GHz with various power division ratios are designed and fabricated using microstrip technology. Good agreement is achieved between the simulated and measured results, justifying that the SCRLH configuration provides a new way of implementing a compact dual-band 90° coupler with arbitrary power split ratios.
An effective method is introduced to overcome the narrow strip width in unequal Wilkinson power divider with high dividing ratio. In the proposed method, the separated microstrip lines of the Wilkinson power divider are replaced by a uniform asymmetrical microstrip coupled lines. It is shown that in the proposed method, the width of the narrow microstrip line is significantly wider in comparison to the narrow microstrip line in the conventional Wilkinson power divider with the same specification. To design the power divider, a suitable error function is defined and then minimized which led to the final dimensions of the power divider. A sample of the designed power divider with 4:1 dividing ratio is fabricated and tested, which indicate the effectiveness of the proposed method.
A novel meander antenna with tri-band operation is presented for WLAN and WiMAX applications. The proposed antenna consists of a rectangular meander with two asymmetrical L-shaped strips. The rectangular meander is used for the lower band operation at 2.5 GHz. The left L-shaped strip is employed to generate the higher resonant mode at about 5.5 GHz, while the right L-shaped strip is employed to create a new resonant mode at 3.5 GHz and enhance the bandwidth of the middle band operation. Prototype of the proposed antenna has been constructed and experimentally studied. The measured 10 dB return loss bandwidths at the resonant frequency of 2.5, 3.5, and 5.5 GHz can be up to 520 MHz (2.18-2.70 GHz), 800 MHz (3.34-4.14 GHz) and 830 MHz (5.07-5.90 GHz), respectively. The antenna is simple in configuration and has a compact dimension of 37×42×1 mm3.
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