Kaijun Song

Novel Ultra-Wideband (UWB) Multilayer Slotline Power Divider With Bandpass Response

A novel ultra-wideband (UWB) multilayer slotline power divider with bandpass filtering response is presented. In the proposed structure, a single isolation resistor is properly placed between the two output ports. Based on the transmission-line equivalent-circuit method, the design equations of the proposed UWB power divider has been derived with the even and odd mode analyses. Experimental results show that excellent impedance matching at all three ports, amplitude and phase balance at the two output ports, isolation between the two output ports, and out-of-band rejection are observed at the UWB band.

Eight-Way Substrate Integrated Waveguide Power Divider With Low Insertion Loss

We describe a compact radial cavity power divider based on the substrate integrated waveguide (SIW) technology in this paper. The equivalent-circuit model is used to analyze the multiport structure, and a design procedure is also established for the structure. An eight-way C-band SIW power divider with low insertion loss is designed, fabricated, and measured. Good agreement between simulated and measured results is found for the pro posed power divider. The measured minimum insertion loss of the eight-way power divider is approximately 0.2 dB and return loss is approximately 30 dB at 5.25 GHz. The measured 15-dB return-loss bandwidth is found to be approximately 500 MHz, and its 1-dB insertion-loss bandwidth is approximately 1.2 GHz. Furthermore, the isolations between the output ports of the eight-way power divider are also discussed.

Compact Ultra-Wideband (UWB) Bandpass Filters With Multiple Notched Bands

A novel asymmetric coupling strip is presented, which can be used in the ultra-wideband (UWB) bandpass filter (BPF) to generate multiple notched bands within the passband. The proposed structure can provide two main paths for the signals, which makes it possible to generate multiple transmission zeroes. The center frequencies and bandwidths of the notched bands can be controlled by tuning the structural parameters. The asymmetric coupling strip has been integrated into a circular disc resonator to construct a compact UWB BPF with multiple notched bands. The measured results agree with the predicted ones closely. These two notched bands centered at 4.3 and 8 GHz have 10-dB rejection fractional bandwidths of about 4.2% and 3.8%, respectively.

Compact Ultra-Wideband Bandpass Filter Using Dual-Line Coupling Structure

This letter presents a novel compact ultra-wideband (UWB) microstrip bandpass filter with spurious response suppression. A dual-mode ring resonator is constituted to allocate its first two resonant frequencies in the UWB band, and the dual-line parallel-coupled structure is used in this compact UWB filter, which is expected to achieve much tighter coupling degree. Simulated and measured results are found in good agreement with each other, showing a wide passband from 4.9 to 10.9 GHz, 15 dB return loss bandwidth of about 5 GHz, minimum insertion loss of 0.49 dB at 7.3 GHz, and wide upper stopband with more than 20 dB attenuation up to 20 GHz.

Novel Broadband Bandpass Filters Using Y-Shaped Dual-Mode Microstrip Resonators

A Y-shaped dual-mode microstrip bandpass filter (BPF) with input-output cross-coupling is presented. The characteristic of the Y-shaped dual-mode resonator has been investigated. The resonance frequencies of the degenerate modes can be adjusted easily to satisfy the bandwidth of the BPF. A parallel-coupling feed structure with a cross coupling has been used to generate two transmission zeros at the lower and upper stopband, which can improve the out-of-band performance. A broadband dual-mode microstrip BPF has been designed, fabricated, and measured. The simulated and measured results are in agreement generally. Within the 3.1 to 5.4 GHz bandwidth, the measured insertion loss, return loss and group delay variation are below 0.5 dB, above 15 dB, and below 0.2 ns, respectively.

Broadband Radial Waveguide Spatial Combiner

A broadband eight-way spatial combiner using coaxial probes and radial waveguides has been proposed and designed. The simple electromagnetic modeling for the radial waveguide power divider/combiner has been developed using equivalent-circuit method. The measured 10-dB return loss and 1-dB insertion loss bandwidth of this waveguide spatial combiner are all demonstrated to be about 8 GHz.

Wideband Four-Way Out-of-Phase Slotline Power Dividers

Two new wideband four-way out-of-phase slotline power dividers are proposed in this paper. The half-wavelength slotlines are employed to construct the presented compact power dividers. Based on the proposed power-dividing circuit, a four-way power divider is implemented with compact size and simple structure. To obtain high isolation among the four output ports and good output impedance matching, another four-way out-of-phase slotline power divider with improved isolation performance is designed by introducing an air-bridge resistor and two slotlines with isolation resistors. The simulated and measured results of the proposed power dividers demonstrate reasonable performance of impedance matching, insertion loss, amplitude balancing, and isolation among the output ports.

Inductance-Loaded Y-Shaped Resonators and Their Applications to Filters

Inductance-loaded Y-shaped resonator and its applications to ultra-wideband (UWB) bandpass filters have been presented in this paper. Based on the odd- and even-mode equivalent circuits, the resonant characteristics of the proposed microstrip resonator with various electrical length and admittance ratio values are investigated. The relationship between the external quality factor and the parameters of the coupling structure has been analyzed to give a design approach for the UWB filter. Two types of UWB bandpass filters are designed to demonstrate the practicality of the proposed resonator. To get tight coupling, the high-impedance parallel-coupled line has been used in the input/output of the first UWB bandpass filter. Both simulated and measured results show that the first UWB filter has a 10-dB return loss bandwidth of 5.6 GHz, a group delay variation of less than 0.3 ns, and a wide upper stopband with more than 20-dB attenuation up to 17.5 GHz. The multilayer technology is applied to the second UWB bandpass filter to provide tight coupling by using the broadside-coupled structures. The measured results show that the multilayer UWB filter exhibits excellent performance, including 1-dB insertion loss and 10-dB return loss bandwidths of 3.3-10.4 GHz with a minimum insertion loss of 0.45 dB at 6.85 GHz, as well as 3-dB insertion loss bandwidth and group delay variation < 0.22 ns over the entire UWB band.

Planar Probe Coaxial-Waveguide Power Combiner/Divider

A novel axially symmetric oversized coaxial waveguide power combiner/divider, which utilizes a planar probe array to transform multiway input to a central oversized coaxial waveguide, is presented in this paper. The use of a coaxial waveguide allows standard transverse electromagnetic design theory to be used, and the characteristics of the coaxial taper transition and the planar probe array are analyzed in detail. A design procedure is also established for the structure. A ten-way planar probe coaxial-waveguide power combiner/divider over the Ku-band is designed and measured. The measured results show a reasonable agreement with the simulated results. The measured 15-dB return-loss bandwidth is approximately 4.3 GHz, and a maximum amplitude imbalance of plusmn 1 dB and a phase imbalance of plusmn5deg are observed in the 11.5-16-GHz band. Furthermore, the isolation between the peripheral ports is also discussed.

Ku-band 200-W Pulsed Power Amplifier Based on Waveguide Spatially Power-Combining Technique for Industrial Applications

A Ku-band 200-W pulsed solid-state power amplifier has been presented and designed by using a hybrid radial-/rectangular-waveguide spatially power-combining technique. The hybrid radial-/rectangular-waveguide power-dividing/power-combining circuit employed in this design provides not only a high power-combining efficiency over a wide bandwidth but also efficient heat sinking for the active power devices. A simple design approach of the presented power-dividing/power-combining structure has been developed. The measured small-signal gain of the pulsed power amplifier is about 51.3 dB over the operating frequency range, while the measured maximum output power at 1-dB compression is 209 W at 13.9 GHz, with an active power-combining efficiency of about 91%. Furthermore, the active power-combining efficiency is greater than 82% from 13.75 to 14.5 GHz.