Search

A novel bandwidth enhancement method using loading multiple parasitic structures to realize broadband miniaturized antenna is proposed. Based on the proposed strategies, one miniaturized wideband dual-polarized dipole antenna covering LTE/CDMA/GSM bands (690–960 MHz) for base-station application is designed. The antenna consists of two folded bowtie-shaped dipoles fed with a pair of crossed baluns, and is further loaded on a ceramic block with high permittivity ($\varepsilon$) for miniaturization. A parasitical square loop is loaded for bandwidth enhancement at a lower frequency. In addition, four split rings with a small square loop are firstly adopted for antenna resonance tuning, the impedance bandwidth is thus improved effectively. The antenna size is only $0.18\,\times \,0.18\,\times \, 0.22\,\,\lambda _{0}$ at the center frequency. The measured result of the fabricated prototype exhibits a relatively large operation bandwidth of 32.73% (VSWR < 1.6) with stable radiation patterns and relatively flat broadside gains. Moreover, to verify the feasibility of the proposed miniaturized antenna element in the base-station application, an array of $2\,\times \, 4$ is further designed. The measured results of the array indicate isolation over 20 dB with an impedance bandwidth of 32%. Due to the good performance and compact feature, the proposed miniaturized broadband antenna element can find large application potential in multiband wireless communication base stations. [ABSTRACT FROM AUTHOR]

An ultrawideband dual-polarized antenna for fifth generation (5G) customer premise equipment is investigated and designed in a compact environment by using a double-loop-dipole structure and a co-planar-slot feeding concept. First, the existing design of dual-polarized octagonal loop dipoles is introduced at first. Then, a novel double-loop-dipole structure and co-planar-slot feeding are proposed and demonstrated in detail from the current distribution and physical structure sides. Finally, the proposed antenna is designed, fabricated, and measured. The measured results present that the proposed antenna has a wide bandwidth of 86% from 2.2 to 5.5 GHz with the VSWR less than 1.8, high polarization isolation of 25 dB, and stable radiation patterns over the desired frequencies of 2.3–5.2 GHz. It is worth mentioning that the proposed ideas can effectively aid in impedance bandwidth improvement without adding additional cost for sub-6G 5G applications. [ABSTRACT FROM AUTHOR]

A low-profile and shared aperture dual-polarized (DP) omnidirectional antenna by reusing the structure of an annular quasi-dipole array is presented. The proposed antenna consists of a center-fed circular patch antenna, an annular quasi-dipole array, a wideband one-to-four power divider integrated with the center-fed circular patch antenna, and two annular strips. The center-fed circular patch antenna is utilized as the driven element for the vertically polarized (VP) radiation. The annular quasi-dipole array fed by the one-to-four power divider produces horizontally polarized (HP) radiation. Simultaneously, it also acts as the VP director to improve VP gain and bandwidth. Besides, the two annular strips enhance the HP omni-directivity and gain. In this way, the VP and HP share the same aperture to improve the profile utilization rate effectively. Due to the symmetry of the basic antenna structure, stable DP donut patterns are obtained within the entire operating bandwidth. For demonstration, a 4.1–5.0 GHz prototype is designed, fabricated, and measured. Under a low profile of $0.13\lambda _{0}$ , the prototype realizes a −10 dB overlapped bandwidth of 20%, high port isolation of above 35 dB, and stable DP donut patterns with horizontal gain larger than 1.8 dBi. [ABSTRACT FROM AUTHOR]

A planar bidirectional circularly polarized (CP) antenna using orthogonal magnetic dipoles (OMDs) without an extra phase shift line is proposed in this work. It consists of a rectangular microstrip magnetic dipole antenna (MMDA) and a loop radiator with two arms directly connected to the open edge of MMDA. The working principle is revealed by the equivalent sources model to provide a clear physical insight at first. The theoretical investigations imply that by controlling the width and the feed locations of the loop antenna on the aperture, the phase and magnitude for CP radiation can be realized in both endfire and backfire directions without introducing an additional phase shift line structure. For demonstration, one antenna prototype is designed and fabricated. The experimental results indicate that an overlapping bandwidth of 5.91% from 2.30 to 2.44 GHz is attained. Compared with the counterpart using OMDs, the proposed antenna exhibits a low design complexity and improved gains of 3.56/1.83 dBic in the endfire/backfire directions. [ABSTRACT FROM AUTHOR]

Low-profile shared-structure dual-polarized (DP) Yagi–Uda antennas are proposed, which are formed by three kinds of basic components, namely DP driven element, DP director, and DP reflector. An open-cavity dipole is utilized as the DP driven element to generate DP endfire radiations. The quarter-wave resonance mode for vertical polarization (VP) and half-wave dipole resonance mode for horizontal polarization (HP) are excited by differential feeding structures in the DP driven element. The open-cavity element is adopted as the DP director or reflector to enhance endfire gain. For the proposed design, two polarization radiators are integrated into one structure, realizing structure sharing, and thus a low profile. Three-element (Ant. 1) and seven-element (Ant. 2) antennas with a profile of 0.1 λ0 are designed, fabricated, and measured. The measured overlapped bandwidth of the Ant. 1 is from 4.11 to 4.83 GHz (16%) with ports isolation higher than 30 dB, and the measured VP and HP gains are from 5 to 6 dBi and 5 to 7 dBi, respectively. The Ant. 2 further increases the DP endfire gain by 2–3 dBi at the overlapped bandwidth of 16.3%. [ABSTRACT FROM AUTHOR]

In this brief, a novel bandpass filter (BPF) with ultra-wide upper stopband performance is proposed and implemented on gallium arsenide (GaAs) integrated passive device (IPD) technology. Firstly, the proposed BPF is designed by introducing a $\boldsymbol{\pi }$ -section to achieve an ultra-wide upper stopband. Following that, the working principle of achieving this ultra-wideband upper stopband performance is further investigated. Finally, to demonstrate the claimed performances, this BPF with a size of $1.63 {\mathrm {\times }}0.62$ mm 2 has been fabricated on GaAs IPD technology and measured by on-wafer probing. The measured BPF with a 3-dB fractional bandwidth (FBW) of 95.3% (1.7-4.8 GHz), exhibits the expected performances, especially the superior upper stopband suppression level better than 20 dB until 110 GHz (34.6 ${f} _{0}$). The simulated and measured results of the BPF are in reasonably good agreement, thus firmly validating the claimed superior performances of the BPF in terms of good frequency selectivity and ultra-wide upper stopband. [ABSTRACT FROM AUTHOR]

A novel method to realize positive phase response of antenna element is proposed conceptually and applied in ±45° dual-polarized dual-beam series-fed metasurface antennas (MSAs). It takes the features of stable beam angle within the relative bandwidth of 10% and dual-polarized dual beams. Benefiting from the positive phase response zone of the antenna, the long-line effect is eliminated and the phase response between the elements is reshaped as expected. Therefore, a stable beam of series-fed array oriented at specific angle is guaranteed accordingly. To achieve the ±45° dual-polarized dual-beam performance, a four-port MSA element with interwoven feeding network is designed and used for further array design. For demonstration, one prototype of MSA array is designed. Considering the band of 4.7–5.2 GHz (10%), the beam angle of the MSAs based on positive phase response control (PPRC) method is oriented to 30°, and the variation versus frequency is less than 6°, which is smaller than the variation of 19° for traditional array. The simulation and measurement results show that stable beam angle is achieved for the dual-polarized series-fed MSA array, indicating a promising candidate for base-station application. [ABSTRACT FROM AUTHOR]

A low-profile broadband vertically polarized microstrip magnetic dipole antenna with endfire radiation is proposed for millimeter-wave (mmWave) applications. For the bandwidth enhancement, a lower resonance is introduced by the parasitic patches firstly. Then, a top-loaded circular probe and an inset proximity-coupled feed structure are employed for adjusting the resonances from the magnetic dipole antenna and the parasitic patches. In this way, a broad impedance bandwidth is attained. After that, a 1 × 4 antenna array prototype is designed, fabricated and tested. Experimental results demonstrate that the proposed array features an impedance bandwidth wider than 19% at 28 GHz mmWave frequency band under an ultralow-profile of 0.075λ0 at the center frequency. [ABSTRACT FROM AUTHOR]

In this paper, low-profile compact microstrip magnetic dipole antennas with large beamwidth and broad bandwidth are proposed for vehicular applications. At first, by introducing a strip on the bottom layer of microstrip magnetic dipole antenna, the electric current sources are introduced for the enhancement of beamwidth together with the magnetic current source. The operation principle of an equivalent complementary source model is then revealed to provide a physical insight. As seen, the half-power beamwidth (HPBW) can be controllable and effectively enlarged by the electric length of the planar magnetic dipole antenna. Next, by using a stub crossing on the strip, the impedance bandwidth is significantly improved comparing with the unloaded counterpart. After that, the antenna size is miniaturized by etching a pair of slots to extend the length of current path. Experimental results indicate that, under a very low profile of 0.016λ0 and 0.032λ0, the antenna prototypes can still achieve an impedance bandwidth of 14.5% and 20.8%, and a maximum HPBW of 99° (E-plane)/180° (H-plane) and 112° (E-plane)/159° (H-plane). It is also demonstrated that when the antenna size is reduced to 0.442λ0×0.284λ0, the impedance bandwidth up to 14.9% and the maximum HPBW of 93° (E-plane)/231° (H-plane) can be guaranteed with a low profile about 0.032λ0. Comparing with other design approaches, the proposed designs feature a very low profile structure, and superior beamwidth and bandwidth properties, as well as simple configuration and compact size. [ABSTRACT FROM AUTHOR]

One kind of interembedded metasurface (MS) structure is proposed and applied to realize miniaturized wideband MS antennas (MSA). Different from conventional MSA, the proposed interembedded MSs are formed by etching slots on the radiating patch with various sawtooth schemes rather than rectangular gaps. Consequently, the resonance frequency of MSA can be decreased due to introducing those interdigital-like capacitances, while obvious miniaturization can be realized accordingly. By optimizing the parameters of the sawtooth radiating slots, a miniaturized antenna using cross-shaped interembedded MS is proposed, achieving an impedance bandwidth of 35.08% and a high gain of about 8.25 dBi with a compact overall size of 0.66 λ0 × 0.66 λ0. Moreover, one further miniaturized antenna using modified cross-shaped interembedded MS is also presented, realizing a larger impedance bandwidth of 41.35% and a high gain of about 6.62 dBi with a smaller aperture of 0.48 λ0 × 0.48 λ0. Compared with conventional MSA, 42% overall size reduction and larger bandwidth can be obtained. The design approach may provide a feasible solution to realize compact MSAs with the unique advantages of large bandwidth, low profile, low cost, and easy fabrication. Due to above good features, the proposed antenna can be a promising candidate for applications in modern wideband wireless communication systems. [ABSTRACT FROM AUTHOR]

In this letter, a millimeter-wave (mm-wave) dual-band bandpass filter is proposed with large bandwidth ratio by using gallium arsenide (GaAs)-based integrated passive device (IPD) technology. To realize small chip size, one dual-mode on-chip resonator is designed by using quasi-lumped capacitors and microstrip lines. In addition, multiple transmission zeroes are generated by further introducing both the electric and magnetic couplings between adjacent resonators. To realize large bandwidth ratio of two passbands, the external quality factors are investigated at both passband, and can be independently controlled. For demonstration, a 28-/50-GHz dual-band bandpass filter is designed, fabricated, and measured. The fractional bandwidth ratio is 7.8, which is much larger than the reported on-chip filters. Meanwhile, very low insertion loss of 0.58-dB is realized for the lower passband at 28 GHz, indicating the proposed dual-band bandpass filter a promising application in mm-wave wireless systems. [ABSTRACT FROM AUTHOR]

In this article, a two-stage broadband GaAs power amplifier (PA) is presented, which consists of an improved Darlington power stage and a drive stage. As the most important part of the two-stage PA, the proposed Darlington power stage can simultaneously achieve large bandwidth and watt-level output power. The circuit analysis of the Darlington structure is carried out for large-size transistors. The bandwidth and gain of the Darlington structure are investigated in three cases with source peaking inductor, interconnection inductor, and compensation inductor. A design procedure for the total PA is developed to provide potential guideline. Furthermore, the total PA was fabricated using 0.15- $\mu \text{m}$ GaAs pHEMT technology. The measured maximum gain in the case of a small signal is 25.9 dB, and the 3-dB bandwidth is from 10.7 to 16.7 GHz (43.8% fractional bandwidth). The maximum power of 36 dBm and the maximum power-added efficiency (PAE) of 46.8% are measured at 13 GHz. To the best of our knowledge, the proposed PA exhibits the highest figure of merit (FOM) when compared with the other previously published works. [ABSTRACT FROM AUTHOR]

A multiresonance antenna based on a nonperiodic square-ring metasurface (MS) is proposed, which has large bandwidth and stable radiation gain. The nonperiodic MS radiator is formed by several adjustable square-ring patches and fed by a microstrip line through a coupling slot. By properly adjusting the widths of these square rings, different resonance modes can be inspired for the MS according to the characteristic mode analysis. Combined with the resonance mode of the coupling slot, multiple adjacent resonance frequencies occur and thus realize a wideband and consistent radiation. For demonstration, a C-band wideband antenna based on the proposed 4 × 4 square-ring MS units with a low profile of 0.06λ0 is accordingly designed and fabricated. The measured results indicate a large impedance bandwidth of 54% (4–7 GHz) and an extremely stable gain with 2 dB gain bandwidth of 32% (4.76–6.54 GHz). [ABSTRACT FROM AUTHOR]

Two new types of multi-functional RF wide-band differential-mode-to-single-ended filtering power dividers are reported in this brief. Their first configurations exploit half-wavelength ring resonators and coupled-line sections to attain common-mode suppression throughout a broad spectral range. Furthermore, asymmetrical coupled-line stages are incorporated in more-advanced schemes to enlarge upper-stopband bandwidth. Two demonstrative microstrip prototypes for the different structures of this RF tri-functional circuit concept that operate at the 1.7–2.7-GHz 4/5-generation long-term-evolution band are built and tested. [ABSTRACT FROM AUTHOR]

In this paper, two 24 GHz horizontally polarized $1 \times 8$ patch antenna arrays were developed for automotive radar applications. The proposed antenna arrays offer the advantages of wide fan beams and high gain. The far-field radiation patterns are widened in the E-plane by disturbing the near-field distribution of each driven patch. In Design I, the driven patch is loaded with a parasitic loop, which functions as a director in the E-plane. Due to the directing effect, the E-plane beamwidth can be increased. The experimental verification prepared for Design I showed that a beamwidth of 130° and a gain of 12.2 dBi can be achieved through this method. To further enhance the beamwidth, another array with each patch loaded with parasitic mushroom-like elements was proposed by Design II. The PMLEs are 180° out of phase to their corresponding driven patch. The cancelation effects can be properly managed to slightly sacrifice the gain of the array in return for a wider beamwidth in the E-plane. Design II exhibits a wider beamwidth of 150° and a lower gain of 11.1 dBi. [ABSTRACT FROM AUTHOR]

In this paper, $N$ -way Gysel power dividers with arbitrary power-dividing ratio are studied by using node voltage and current method for the first time. Closed-form analytical equations are derived for the design of the proposed Gysel power divider with arbitrary power division on arbitrary terminated impedance. Parameters that might influence the frequency bandwidth are investigated and optimized to achieve balanced performance. For verification, 3-way and 6-way Gysel power dividers are, respectively, designed, fabricated, and measured at a center frequency of 3.45 GHz, with dividing ratio 1:1:1, 1:2:3, 1:1:1:1:1:1:1, and 1:1.2:1.2:1.5:1.5:2, respectively. Good agreements can be observed among expected, simulated, and measured results, indicating the validity of the proposed strategies. [ABSTRACT FROM AUTHOR]

The low-profile dual-polarization frequency-selective rasorbers with very simple structures are investigated. Based on an equivalent circuit model, the operating principle and design method are first studied. One rasorber using lossy cross-frame elements and double-square loops is then proposed, which exhibits two absorption bands at the two sides of one passband. Moreover, the rasorbers with reduced cell size are further developed to stabilize the angular response. Under normal incidence, an insertion loss of about 0.26 dB is obtained at 4.25 GHz, the fractional bandwidth for reflection less than −10 dB is over 100%, and the thickness is around ${\text{0.1}}\,\lambda _{L}$. For demonstration, the rasorber prototypes are fabricated and measured, while reasonable agreements are observed accordingly. [ABSTRACT FROM AUTHOR]

The characteristics of a modified dual composite right/left-handed (D-CRLH) unit cell is investigated, which can be applied to design bandpass filters. The proposed unit cell is very compact and contains ten structural variables, which provides large design flexibility to realize different frequency responses. To assist the design of D-CRLH unit cells, the resonant characteristics are analyzed, and the design strategies for performance improvements are given accordingly. Furthermore, the design method of D-CRLH bandpass filters is introduced, with which the desired performance can be obtained by dimensions modifications of adopted resonators. For demonstration, three D-CRLH bandpass filters aimed at different performance are designed and experimentally verified. Good agreement between the measurements and design goals can be observed. [ABSTRACT FROM PUBLISHER]

A millimeter-wave series–parallel patch antenna array is presented, in which the dual-slot feeding structure is handily implemented using the intrinsic field distribution of TE20 mode in substrate-integrated waveguide (SIW). One 28 GHz patch antenna element fed by the TE20-mode SIW is first designed, achieving a 10 dB impedance bandwidth of 10.2% and a simulated peak gain of 6.48 dBi. Based on the antenna element, a $4 \times 4$ array with a compact series–parallel differential feeding network is developed accordingly. Due to the novel compact SIW-based series–parallel feeding network, the antenna array can achieve superior radiation performances, which is the highlight of this communication. The simulation and measurement results of the proposed antenna array are in good agreement, demonstrating a performance of 8.5% impedance bandwidth, 19.1 dBi peak gain, symmetrical radiation patterns, and low cross-polarization levels (−30 dB in E-plane and −25 dB in H-plane) in the operating frequency band of 26.65–29.14 GHz. [ABSTRACT FROM AUTHOR]

Two novel high selectivity wideband balanced filters based on open/shorted stubs with multiple transmission zeros are proposed in this brief. Two and four transmission zeros near each passband for the differential mode (DM) can be easily achieved for two balanced filters. In addition, the common mode can be suppressed with three and five transmission zeros with an insertion loss greater than 15 dB/20 dB over a wide frequency band. Two prototypes with 3-dB fractional bandwidths of 67.6% and 37.8% for the DM with an insertion loss greater than 15 dB (7.0–12.7 GHz) are designed and fabricated. A good agreement can be observed between the measured results and the theoretical expectations. [ABSTRACT FROM PUBLISHER]

A straight parasitic strip, closely and horizontally placed above a perfect electrical conductor ground plane, is used to greatly enhance the radiation of a horizontally positioned center-fed half-wave dipole through the phase compensation from the strip. The method is discussed and validated by both full-wave electromagnetic simulation and experiments. Using the parasitic strip, a horizontal dipole with a height of 1/20 wavelength above the ground exhibits an input resistance of 62 $\Omega $ and gain of 7.8 dBi while the dipole without the strip and a dipole with a height of a quarter wavelength above the ground realize the resistance of 5/72 \Omega $ and the gain of 4.3/7.8 dBi across a \vert S_{11}\vert \leq -10 -dB bandwidth of 0.6%, respectively. [ABSTRACT FROM PUBLISHER]

A compact tunable power divider is proposed in this brief. The power divider can achieve a wide frequency tuning range and good matching and isolation performances. Theoretical equations for the characteristic impedance and the electrical length of the power divider are derived. For demonstration, a prototype working at 1.5 GHz as the center frequency is designed and fabricated. The measured results show that the power divider can be effectively tuned within the frequency range of 104% (0.83–2.4 GHz) with a return loss and isolation better than 20 dB and insertion loss varying between −3.3 dB and −3.5 dB. [ABSTRACT FROM PUBLISHER]

Three compact planar crossovers based on strong coupled lines loaded with open stubs are proposed in this paper. Two conventional coupled lines loaded with different electrical wavelength open stubs are used to realize the single/dual passband. The center frequencies of the three planar crossovers can be adjusted over a wide frequency band by changing the even-/odd-mode characteristic impedance of the coupled lines and the characteristic impedance of the open stubs. Three compact planar crossovers located at 1.78, 1.88, and 1.02/2.98 GHz are designed and fabricated for verification. The theoretical and measured results are in good agreement and show good in-band performances. [ABSTRACT FROM PUBLISHER]

A novel polarization-reconfigurable mechanism based on a polarization-rotation artificial magnetic conductor (PRAMC) structure is proposed. A new polarization-reconfigurable antenna is designed by combining a PRAMC-based multipolarized dipole antenna with a RFIC switch-based network, in which three polarization states of right-handed, left-handed circular polarization (RHCP, LHCP) and +45^\circ linear polarization (LP) can be realized by controlling the dc bias of the switches accordingly. The multipolarization antenna is well designed for offering three polarization states. A large 3-dB axial ratio (AR) bandwidth of 15.5%, a wide 3-dB AR beamwidth for CP states and a large cross-polarization isolation of more than 50 dB for LP state together with a broad impedance bandwidth of 20.5% are obtained. A switch network is used to generate three feeding modes, and the performance of the RF-integrated circuit (RFIC) switches is experimentally verified. A prototype of the proposed polarization-reconfigurable antenna is fabricated and tested. Good agreements between the measured and simulated results are observed, which indicates good performances of the proposed antenna. [ABSTRACT FROM PUBLISHER]

A novel multifunctional reconfigurable filter with three different transmission modes using transversal signal-interaction principles is proposed. These three operational modes allow to reconfigure the engineered filtering device as ultra-wideband bandpass filter, narrow-band bandpass filter (NB BPF), and ultra-wideband band-stop filter (UWB BSF). By turning on/off the RF switches, the transmission lines and stubs can be dynamically connected or disconnected so that the three transmission modes can be discretely selected. For the UWB-BPF mode, the 3-dB bandwidth is 95.7% (1.51–4.38 GHz) with minimum in-band insertion loss of 0.94 dB. For the NB-BPF mode, the 3-dB bandwidth is 25.3% (2.55–3.29 GHz), the minimum in-band insertion loss is 0.8 dB, and the stopband rejection is higher than 11.6 dB. For the UWB-BSF mode, the 3-dB bandwidth is 106% (1.41–4.59 GHz) with in-band insertion loss above 10 dB. [ABSTRACT FROM PUBLISHER]

In this paper, a novel thin, broadband, single polarization capacitive surface-based absorber is proposed and investigated. First, the impedance of a substrate and matching surface are analyzed and used for the determination of the structure parameters of the microwave absorber. Second, by utilizing infinite strip gratings with lumped resistors, a capacitive surface-based absorber is presented with 48.6% thickness reduction and 11.7% bandwidth enhancement in comparison to the Salisbury screen. Finally, a prototype of the proposed absorber is fabricated and measured for validation. The proposed method provides an efficient way for the design of thin broadband microwave absorbers. [ABSTRACT FROM PUBLISHER]

A novel kind of tri-band bandpass filter (BPF) is presented, which is based on the dual composite right- and left-handed resonator. The proposed tri-band BPF is very compact with over 30% size reduction over the previously published ones. The center frequencies and bandwidths can be controlled independently with large flexibility. In addition, the return losses can also be adjusted independently, resulting in the optimal impedance matching for the proposed designs. Finally, one tri-band BPF is designed for demonstration, which simultaneously exhibits compact circuit size and preferable in-band performances. Good agreement between the measured and simulated results is observed, verifying the validity of the design strategies. [ABSTRACT FROM PUBLISHER]

A compact reconfigurable circuit performing as either Single Pole Double Throw switch or power divider is proposed and demonstrated, based on the concept of modes match and impedance match between substrate integrated waveguide (SIW) and half-mode SIW (HMSIW). A switchable HMSIW unit is first proposed and then followed by the design of the reconfigurable circuit. For demonstration, the proposed circuit is designed and fabricated on the substrate of Rogers 5880LZ with thickness 1.026 mm. When the circuit works as a switch and Port 2 is at ON-state, the measured S11 < -15 dB, S22 < -13 dB, S21 > -1.5 dB, and S23 and S13 < -27 dB; meanwhile, when the circuit performs as a power divider, the measured S11 < -14.5 dB, and S21 and S31 > -4.35 dB, over the frequency band from 4.6 to 5.3 GHz. The good performances show the advantages of proposed circuit topology, which can be an excellent candidate for multifunctional microwave or millimeter-wave circuits. [ABSTRACT FROM PUBLISHER]

Two new wideband in-phase and out-of-phase balanced power dividing/combining networks are proposed in this paper. Based on matrix transformation, the differential-mode and common-mode equivalent circuits of the two wideband in-phase and out-of-phase networks can be easily deduced. A patterned ground-plane technique is used to realize the strong coupling of the shorted coupled lines for the differential mode. Two planar wideband in-phase and out-of-phase balanced networks with bandwidths of 55.3% and 64.4% (\vert S{ dd21,31}\vert<4\ {\ {dB}}) for the differential mode with wideband common-mode suppression are designed and fabricated. The theoretical and measured results agree well with each other and show good in-band performances. [ABSTRACT FROM PUBLISHER]

A compact single-layer substrate integrated waveguide (SIW) monopulse network for Ku-band tracking system applications is investigated and demonstrated in this work. The feeding network and the monopulse comparator are integrated into a substrate with a structure size of 8.2\lambda0\times 9\lambda0 at center frequency while 32 output ports are welded perpendicularly for connecting active transmit/receive modules. The optimal design of a 3-dB coupler with metallic slots and phase shifter with dual steps is presented. The relative frequency bandwidth (\vert S11\vert, \vert S22\vert, and \vert S33\vert<10\ \ dB) of the network is 6%, in which the phase imbalance of all ports is less than 5.5° [root mean square (rms)], the power imbalance is about 0.5 dB (rms). The insertion losses are about 3–5 dB and the isolations between the three channels are all better than 25 dB. The good performances of this SIW-based monopulse network are validated by measurements, showing the advantages of low cost, light weight, easy fabrication, etc. It presents an excellent candidate for Ku-band tracking systems or up-band millimeter-wave systems. [ABSTRACT FROM PUBLISHER]

This paper presents a wideband 60-GHz antenna array with a dual-resonant slot-patch structure. A multilayered low-temperature co-fired ceramic substrate was used for antenna fabrication. A half-wavelength resonant slot was designed with a backed substrate-integrated waveguide (SIW) cavity to enhance the front radiation. The inverted microstrip center-fed structure was designed for easy signal excitation and superior impedance matching. A parasitic patch was also applied to enhance for bandwidth and gain enhancement. The effects of the SIW cavity-backed slot antenna with and without parasitic patches were empirically examined. The simulated results show that adding parasitic patches increased the resonance of the poles and improved antenna gain by 1.85 dB and bandwidth by 9%. A 2\,\times\,2 dual-resonant slot-patch antenna array was designed to further enhance the gain and bandwidth. The equipment setup for on-chip measurements of gain and radiation patterns was established. The measured S11 showed a wide bandwidth of 23%. The measured gain for the four-element antenna array was 9 dBi with slight fluctuations over the 57–64-GHz frequency range. [ABSTRACT FROM AUTHOR]

An unequal power divider with tunable operating frequency is proposed for the first time, in which the operating frequency can be tuned over 100% around the center frequency. The theoretical analysis for the characteristic impedance and the electrical length are presented. A prototype with the tunable frequency from 0.85 GHz to 2.4 GHz is designed and fabricated. Good agreements can be observed between the simulated and measured results. [ABSTRACT FROM PUBLISHER]

A high selectivity bandpass filter loaded with open stubs using dual-mode ring resonator is presented in this letter. Sixth-order passband with six transmission zeros close to the passband is realized with two open stubs and open/shorted coupled lines. The transmission zeros near the passband can be adjusted conveniently by only changing the characteristic impedances of the coupled lines. For demonstration, a planar bandpass filter (3 dB bandwidth 20.6%) is designed and fabricated. Good filtering performance and high selectivity for the filter are realized and experimentally verified. [ABSTRACT FROM PUBLISHER]