Haidong Chen

Compact Substrate Integrated Waveguide (SIW) Monopulse Network for

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 8.2λ0×9λ0 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 ( | S11|, | S22|, and ) 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.

Ku

A compact four-way dual-band microstrip power divider is investigated and demonstrated in this letter. The proposed divider reduces the number of transmission line sections by decomposing a single dual-band transformer into a four-way power divider. The theoretical equations for isolation structures and the design procedures of the power divider are presented. For demonstration, a prototype operating at 1 and 2 GHz is fabricated and measured. Good agreements can be observed between the simulated and measured results.

-Band Tracking System Applications

In this work, an analytical approach to the design of high isolation dual-gate GaN-HEMT single-pole double-throw (SPDT) switches is presented. An R-C-R circuit is used as a band-rejection filter at the specified frequency in the OFF-state in order to realize the high isolation performance. Simulated performance of a complete SPDT using the proposed approach is presented. From DC to 3 GHz, the simulated isolation is 10 dB higher than the case without R-C-R circuit type, demonstrating the approach feasibility and effectiveness.

A Compact Four-way Dual-band Power Divider Using Lumped Elements

The compact single-layer substrate integrated waveguide (SIW) 3-dB side-wall directional couplers with/without metallic dome for Ku-band monopulse comparator application are studied and demonstrated in this paper. These couplers with/without dome achieve ±0.35 dB/±0.7 dB power equality, -24.7 dB/-16 dB isolation, and -24.4 dB/-15 dB return loss, ±0.60 °/0.12 ° phase difference, respectively, over 17% bandwidth. Considering the bandwidth requirement and fabrication technique, the coupler without the dome is selected to integrate into the monopulse comparator. The monopulse comparator is fabricated and measured, indicating good performances for the Ku-band tracking system.

Dual-gate GaN-HEMT SPDT switch with high isolation

A novel balanced filter circuit based on open/shorted loaded stubs is proposed. Two transmission zeros near the passband for the differential mode can be easily achieved. In addition, the common mode can be suppressed from 0 GHz to three octaves with insertion loss greater than 25 dB, due to the all-stop transmission characteristic of the coupled lines. A prototype with 3-dB fractional bandwidth of 12.9% for the differential mode is designed and fabricated.

Substrate integrated waveguide(SIW) 3-dB narrow wall directional couplers for monopulse comparator application

ABSTRACT Half-mode substrate integrated waveguide (HMSIW) switchable unit, built by HMSIW section with loaded single or multi-microstrip shunt stub(s), was proposed in this work. Both shorted and opened stubs were studied, investigated and compared, bandwidth enhancement method for proposed switchable units was proposed and demonstrated. Based on these switchable units, narrowband and broadband HMSIW single-pole-single-through (SPST) switches, SIW SPST switch and SIW/HMSIW-based single-pole-double-through (SPDT) switch were designed, fabricated and measured. Good performances were observed experimentally for these proposed circuits, showing the advantages of proposed concept and an excellent candidate for switchable or reconfigurable SIW/HMSIW circuits or systems.

Balanced filter circuit based on open/shorted loaded stubs

Two novel dual-/tri-band branch line couplers with high power division isolation using coupled lines are proposed in this brief. Two conventional couplers loaded with quarter-wavelength open/shorted coupled lines are adopted to realize the dual or triple bands. Each band has a high isolation due to the introduced transmission zeros. The center frequencies of the two planar couplers can be adjusted over a wide frequency band by changing the even/odd-mode characteristic impedances of the coupled lines. Two planar dual-/tri-band couplers located at 0.75/1.32 GHz, 0.69/1.0/1.4 GHz are designed and fabricated for verification. Good agreement can be observed between measured results and theoretical expectations.

HMSIW-based switchable units using super compact loaded shunt stubs and its applications on SIW/HMSIW switches

Two kinds of reconfigurable impedance matching networks with controllable phase shift are proposed. The reconfigurable networks can match different loads with desired phase shift at center frequency and no extra phase shifter is needed. The two networks are realized by using varactor diodes and switches, respectively. The design equations and achievable phase shift range of the two networks are derived. Two prototypes working at 1 GHz were fabricated for verification. The measured results show good return loss response and precise phase shift value.

Dual-/Tri-Band Branch Line Couplers With High Power Division Isolation Using Coupled Lines

This paper presents wideband forward-wave coupled-line couplers loaded with metallic via walls. The proposed coupler features wide bandwidth. The two via walls enable good impedance matching of even and odd modes. Moreover, the proposed structure can remain stable phase difference over a wide frequency range, yielding wide bandwidth. The -1 dB bandwidth of the 3-dB coupler is 45% (6.8-10.75 GHz). Compared with the traditional coupled-line coupler, the proposed coupler achieves wide bandwidth.

Reconfigurable Impedance Matching Networks with Controllable Phase Shift

Two novel bandpass filters with improved upper stopband using a pair of dual-behaviour resonators (DBRs) are presented in this paper. By utilising coupled lines and open stubs, the second harmonic can be eliminated easily. Extended DBRs with different lengths are used to obtain more transmission zeros to suppress the third and fourth harmonic. 15-dB rejection level in the upper stopband from 1.3f0 to 2.72f0 and 5.2f0 (f0 is the centre frequency of the passband) can be obtained for the two proposed bandpass filters, respectively. Two planar bandpass filters (3-dB fractional bandwidths 9.3%, 8.9%) are designed and fabricated. Good agreements are presented for the theoretical and measured results, which show good in-band filtering performances and high selectivity.