Yu Shi

A NOVEL DUAL MODE SUBSTRATE INTEGRATED WAVEGUIDE FILTER WITH MIXED SOURCE-LOAD COUPLING (MSLC)

A novel single-cavity dual mode substrate integrated waveguide (SIW) fllter with mixed source-load coupling (MSLC) is presented. By using an interdigital slot-line (ISL) to introduce mixed coupling between source and load, the proposed fllter with only one cavity could have three transmission zeros which can be controlled ∞exibly. Under the circumstances, the fllter exhibits better frequency selectivity in comparison with conventional dual mode SIW fllters. An experimental fllter with a center frequency of 10GHz and a 3dB fractional bandwidth of 6.0% is designed, fabricated, and measured to validate the proposed structure. Measured results are provided to show good performance and in agreement with the simulated ones.

Compact Tri-Band Bandpass Filter Using Open Stub Loaded Tri-Section lambda/4 Stepped Impedance Resonator

A modified tri-mode λ/4 stepped impedance resonator (SIR) is proposed, in which a shunt open stub is loaded in the conventional λ/4 tri-section SIR. The resonant frequencies and frequency ratios can be properly controlled by adjusting the loaded open stub. A compact second-order tri-band bandpass filter (BPF) based on two coupled proposed open stub loaded λ/4 tri-section SIR is presented. A pair of transmission zeros (TZs) are generated at the lower and upper stopband of each passband for high selectivity and excellent band-to-band isolation. A tri-band BPF with the central frequencies of 1.92, 3.50, 5.75 GHz, and respective fractional bandwidths of 5.4%, 4.0%, and 2.4% is designed and fabricated. Measured results show good agreement with simulations. Moreover, the circuit only occupies 0.09 λg ×0.10 λg.

Compact LTCC source-load coupled SIW filter using mixed coupling

A novel substrate integrated waveguide (SIW) filter with source-load coupling based on low temperature co-fired ceramic (LTCC) technology is proposed. By introducing mixed coupling into input/ output SIW in middle layer, the filter not only has good selectivity owing to the controllable transmission zeros, but also has a compact size by the virtue of LTCC structure. Based on the flexible coupling manner in multilayer structure, a demonstration second-order bandpass filter with three transmission zeros has been designed and fabricated. Good agreement between measured and simulated results is observed.

Miniaturized mixed-cross coupling bandpass filter with source–load coupling

A miniaturized trisection bandpass filter (BPF) with improved stopband characteristics is presented. The proposed BPF consists of three stepped impedance resonators (SIRs), where the nonadjacent SIRs share a common shorted stub, and the other SIR is embedded inside the nonadjacent SIRs. To improve frequency selectivity, mixed-cross (M-C) coupling and source–load (S–L) coupling were introduced in the nonadjacent resonators and source/load ports, respectively. Owing to the M-C and S–L couplings, multiple transmission zeros (TZs) can be employed for high skirt selectivity and upper wide stopband. A new BPF centered at 2.45u2009GHz with 17.6% fractional bandwidth has been designed and fabricated to verify the validity of the proposed method. The measurement result shows four finite TZs in the stopband, located at 2.09, 2.98, 4.64, and 12.47u2009GHz, respectively. The circuit only occupies 6.70u2009×u20098.60u2009mm2

COMPACT MIXED-CROSS COUPLED BANDPASS FILTER WITH ENHANCED FREQUENCY SELECTIVITY

In this paper, a compact three-order mixed-cross coupled bandpass fllter (BPF) with enhanced frequency selectivity is proposed. Multiple transmission zeros (TZs) can be obtained near the passband for high frequency selectivity by introducing mixed-cross coupling between the nonadjacent resonators. The frequency-dependent mixed- cross coupling matrix of the proposed fllter is presented to explain the occurrence of the TZs caused by mixed-cross coupling. A new BPF centered at 2.7GHz with 11.5% fractional bandwidth has been designed and fabricated to verify the validity of the proposed method. The measurement result shows four flnite TZs in the stopband, located at 1.74GHz with 52.16dB rejection, 2.53GHz with 24.67dB rejection, 3.83GHz with 47.52dB rejection, and 7.75GHz with 54.83dB rejection, respectively. The circuit only occupies 6.2£7.6mm 2 .

Compact bandpass filter with wide stopband using stepped impedance resonators

A compact bandpass filter with wide stopband using stepped impedance resonators has been designed and fabricated. And open ended stubs for frequency fine tuning are introduced. The new passband filter was analyzed, simulated and fabricated. Measured results are in good agreement with the electromagnetic simulation results. Moreover the circuit only occupies 20.1 × 17.1 mm2(≈0.21 λg × 0.16λg).

Miniaturized Bandpass Filter with Improved Stopband

Abstract In this article, a miniaturized bandpass filter with improved stopband using a short-circuit centered stepped impedance resonator is presented. An extra transmission zero can be provided near the passband for good frequency selectivity by introducing mixed electric/magnetic coupling in the proposed filter. Multiple transmission zeros are introduced in the upper stopband via, taking advantage of the harmonic effects of the distributed transmission line. Meanwhile, source-load coupling is introduced to improve the skirt selectivity via shifting the transmission zeros to the vicinity of the passband. The odd- and even-mode analytical method is used to design the filter. To verify the validity of the proposed technique, the new bandpass filter has been analyzed, simulated, and fabricated. The measurement results agree well with the full-wave electromagnetic designed responses.

A band-notched UWB slot antenna with high skirt selectivity and controllable bandwidth

A compact ultra-wideband (UWB) antenna with sharp band-notched characteristics and controllable notched bandwidth is presented. The proposed antenna consists of an inverted U-shaped slot on the ground plane and a radiation patch similar to the slot which is fed by a 50-Ω microstrip line. By slitting an inverted U-shaped slot on the radiation patch and embedding an inverted U-shaped strip near the top edge of the ground aperture, a second-order notched band of WLAN (5.15-5.85GHz) is achieved. Compared with the traditional band-notched antenna, the selectivity of the notched band is greatly improved. Moreover, the bandwidth of either the lower or upper rejected band can be independently adjusted by changing the size of the slot and the strip, respectively. The antenna is fabricated on a standard low-cost FR4 substrate with a whole size of 27*20*1 mm3. Good agreement is achieved between simulated and measured results.

Compact dual-band BPF with improved stopband

A compact dual-band bandpass filter (BPF) with improved stopband characteristics using stepped impedance resonators (SIRs) is presented. Multiple transmission zeros can be realized near the passbands of proposed filter by the cancelling effects of mixed electric and magnetic couplings. Dualband can be achieved by combining two sets of independent resonators with common input/output ports. A 2.4/5.4GHz dualband BPF for wireless local area network (WLAN) has been designed and fabricated to verify the validity of the proposed method. The measurement results show six finite transmission zeros in the stopband for improved stopband.

A highly linear short-wave ultra-wideband balanced amplifier

A Short-wave ultra-wideband balanced amplifier with high linearity and lower noise based on balanced structure is presented. The amplifier is realized by Equilibrium structure, Balun broadband matching, Coupler feedback and Power backoff technology. Equilibrium structure is used to greatly improve the second order distortion and Lossless coupler feedback to reduce the noise. The RF frequency is 1.5∼100MHz. The test results show that the gain is 13 dB, the gain flatness is 0.1 dB, the maximum of noise figure is 3.1 dB, the referred 1-dB compression point (P1dB) is above 30dBm the second order output intercept point (OIP2) is above 90dBm, and the third order output intercept point (OIP3) is above 49dBm.