Topic
Return loss
About: Return loss is a research topic. Over the lifetime, 11090 publications have been published within this topic receiving 97603 citations.
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Patent•
23 Feb 1999
TL;DR: In this article, a novel tunable optical add/drop filter for the all-optical wavelength-division-multiplexing (WDM) network applications is described, which can add or drop part of the high transmission capacity signals of a WDM link.
Abstract: In all-optical networks, optical switching and routing become the most important issues for interconnecting the transport network layers. This invention describes a novel tunable optical add/drop filter for the all-optical wavelength-division-multiplexing (WDM) network applications. This filter can add or drop part of the high transmission capacity signals of a WDM link. It can be used to decentralized access point in the access network or as small core network node to realizing branching points in the network topology. It works in both wavelength and space domains. It has the advantages of: 1) High throughput and low voltage operation; 2) Wide tuning range and therefore, high channel capacity; 3) High isolation and high directivity between input and output ports; 4) Compact device packaging is possible as compares to the conventional grating and mechanical switching type of add/drop filter; 5) Multiple ports add/drop tunable filters can be realized with this invention to interconnect multiple WDM networks. This novel add/drop filter can be used in various WDM topologies. It enhances the performance of the conventional tunable filter by re-routing the rejected wavelengths back to network, which not only save the precious optical energy, but also cut down the return loss of the device.
109 citations
TL;DR: In this article, the branch-line coupler can be extended by suitably incorporating additional sections into the composite design to achieve better return loss and isolation of the three-and four-section couplers.
Abstract: The branch-line coupler may be redesigned for crossover application. The bandwidth of such a coupler can be extended by suitably incorporating additional sections into the composite design. Laboratory tests on microstrip prototypes have shown the return loss and isolation of the three- and four-section couplers to be better than 20 dB over bandwidths of 22% and 33%, respectively. The insertion losses and group delays vary by less than ±0.05 dB and ±1 ns, respectively, for both prototypes.
108 citations
TL;DR: In this paper, a new broadband 90deg hybrid feed network is proposed to have a bandwidth of 75% for the 10dB return loss, good two output ports amplitude balance and a consistent 90deg (plusmn3deg) phase difference between two output output ports.
Abstract: A novel wideband circularly-polarized patch antenna is presented First, a new broadband 90deg hybrid feed network is proposed to have a bandwidth of 75% for the 10-dB return loss, good two output ports amplitude balance and a consistent 90deg (plusmn3deg) phase difference between two output ports Then, a circular patch antenna fed by four sequential-rotation proximity-coupled L-probes orientated to have phase of 0deg, 90deg, 180deg and 270deg is presented The four L-probes are connected to the respective ports of a feed network comprising a pair of the proposed broadband 90deg hybrid It is found that the antenna can deliver a measured impedance bandwidth of 794% from 104 to 241 GHz for SWR 3 dBi The simulated impedance bandwidth is 94% from 09 to 25 GHz for SWR 3 dBi Good agreement is observed between simulation and measurement
107 citations
TL;DR: In this article, a three-port microstrip multifrequency diplexer is proposed to take 10, 12, 19, and 21 GHz into port 1 and to separate 10 and 19 GHz to port 2 and 12 and 28 GHz to part 3 with minimal dispersion.
Abstract: This paper introduces a three-port microstrip multifrequency diplexer used in a phased-array transceiver system that employs band-stop filters with open-circuited stubs for band selection and separation. The diplexer is designed to take 10, 12, 19, and 21 GHz into port 1 and to separate 10 and 19 GHz to port 2 and 12 and 21 GHz to part 3 with minimal dispersion. The insertion loss for each frequency varies from 0.4 to 3.4 db and the return loss is better than 10 dB. The isolation between channels at the four frequencies is greater than 50 dB. Each passband created between adjacent stopbands has a bandwidth over 1 GHz. The microstrip diplexer is designed using periodic stubs that collectively have the advantages of low insertion loss, high isolation and rejection, wide-band performance on each channel, and easy fabrication. This type of diplexer has many applications in multifrequency transceivers for communication systems.
106 citations
TL;DR: In this article, a wideband fifth-order bandpass filter (BPF) is proposed and designed using the U-slotted substrate integrated waveguide (SIW) cavities.
Abstract: A wideband fifth-order bandpass filter (BPF) is proposed and designed using the U-slotted substrate integrated waveguide (SIW) cavities. The U-shape slots, etched on the SIW cavity, are used to form up a new multiple-mode resonator (MMR) in order to achieve a wide passband of operation while keeping the overall size of the filter circuit to be much compact. The proposed fifth-order SIW filter is 2.5 times in size reduction compared with the traditional fifth-order SIW filters using the single-mode SIW cavities. In order to prove the validity, one wideband SIW BPF on a single layer printed circuit board (PCB) is designed and experimentally examined. The measured results show that the filter achieves an insertion loss of 1.1 dB at 8.5 GHz, return loss of higher than 11 dB and 3 dB fractional bandwidth of 42%. The measured results are in good agreement with the simulated results.
106 citations