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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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Journal ArticleDOI
TL;DR: In this paper, a scalable turnstile-based orthomode transducer was proposed to overcome the current practical bandwidth limitations by adding a single-step widening at the junction of the four output rectangular waveguides.
Abstract: A 64% instantaneous bandwidth scalable turnstile-based orthomode transducer to be used in the so-called extended C-band satellite link is presented. The proposed structure overcomes the current practical bandwidth limitations by adding a single-step widening at the junction of the four output rectangular waveguides. This judicious modification, together with the use of reduced-height waveguides and E-plane bends and power combiners, enables to approach the theoretical structure bandwidth limit with a simple, scalable and compact design. The presented orthomode transducer architecture exhibits a return loss better than 25 dB, an isolation between rectangular ports better than 50 dB and a transmission loss less than 0.04 dB in the 3.6-7 GHz range, which represents state-of-the-art achievement in terms of bandwidth.

63 citations

Journal ArticleDOI
TL;DR: In this paper, a broadside-coupled Lange coupler, a microstrip ring hybrid, and a hairpin resonator incorporating a complementary slow-wave structure are investigated for reducing the size and enhancing the performance of microwave and millimeter-wave distributed circuits in CMOS.
Abstract: Multilayer design techniques are investigated for reducing the size and enhancing the performance of microwave and millimeter-wave distributed circuits in CMOS. Various distributed passive circuits are implemented in a standard 0.25-mum RF/mixed-signal process, including a novel broadside-coupled Lange coupler, a microstrip ring hybrid, and a hairpin resonator incorporating a complementary slow-wave structure. The broadside-coupled Lange coupler exhibits -3.3 to -3.35 dB through, -3.3 to -3.7 dB coupling, more than 12-dB isolation, and 15-dB return loss across 25-35 GHz while occupying only 217 times185 mum of chip area. The multilayer ring hybrid has -3.1 to -3.18 dB through, -5.1 to -5.7 dB coupling, and more than 17-dB isolation and 10-dB return loss from 25-35 GHz while occupying 282 times314 mum. A slow-wave structure based on multilayer complementary design principle is implemented for hairpin resonators. The measured quality factor of the multilayer complementary slow-wave hairpin resonator increases to about 14.5 from 11.3 for a similar sized resonator with a single-layer slow-wave structure, while retaining similar size-reduction properties as the latter

63 citations

Journal ArticleDOI
TL;DR: In this paper, the optical gain of reflective optical network units (ONUs) was theoretically analyzed and experimentally confirmed in the presence of Rayleigh backscattering, reflection interferences and ASE noise.
Abstract: The optical gain of reflective optical network units (ONUs) may produce a critical amplifying feedback on the single-fiber transmission impairments. In this paper, its influence on the passive optical networks transmission with reflective-ONU is theoretically analyzed and experimentally confirmed. Analytical expressions for the optical crosstalk-to-signal ratio and the Q-parameter in presence of Rayleigh backscattering, reflection interferences and ASE noise are given. As a resulting design guideline, the ONU gain should be adjusted to about 3 dB below the total link loss; in addition, component return loss at the drop section must be higher than 30 dB. Experimental results with two basic types of reflective-ONUs, namely a loop structure formed by a Mach-Zehnder modulator and an optical amplifier, and another one employing a reflective-SOA, are in agreement with the theoretical approach.

63 citations

Proceedings ArticleDOI
Gyubok Park1, Minchan Kim1, Taesik Yang1, Joonho Byun1, Austin Kim1 
01 Jun 2009
TL;DR: In this paper, the authors proposed a suspended line between antennas to operate like a band stop filter to maintain high isolation in the LTE-700 MIMO system, which can be applied to commercial RF devices such as a USB dongle and an express card for mIMO systems.
Abstract: Fig. 3 shows the measured and simulated return loss of the proposed antenna. The lower band is tuned at about 770 MHz and has a bandwidth (1:3 VSWR) of 70 MHz (Antenna 1:735–810MHz, Antenna 2:740–800MHz), which satisfies the operating bandwidth of the LTE band class 13 (746–787 MHz). The GPS band has a bandwidth (1:3 VSWR) of 200 MHz (1410–1610MHz), which satisfies the operating bandwidth of the GPS at L1 band (1565∼1585MHz). The PCS and UMTS band has a bandwidth (1:3 VSWR) of 400MHz (1790–2190) PCS and UMTS band (1810–2170MHz). The obtained bandwidths meet the bandwidth requirement of the LTE band class 13, GPS at L1 band, PCS and UMTS mobile handset systems. The average gain was measured in the Reverberation 3D chamber [2] and the corresponding radiation patterns are shown in Fig. 4. Table I. shows the average gain data of the whole frequency bands and table II. shows the important factors for LTE700 MIMO performance. When the suspended line is applied to the proposed antennas, those have better performance compared to antennas excluding suspended line. Suspended line between antennas is able to operate like a band stop filter. This is an important factor to maintain a high isolation. The proposed antennas connected by suspended line can easily be applied to commercial RF devices such as a USB dongle and an express card for MIMO systems. The demands of MIMO system will significantly increase in the near future. Proposed structure of the antennas and suspended line is very promising.

63 citations

Journal ArticleDOI
TL;DR: The capability of reconfigurable monopulse beams ensures that the proposed antenna is a good candidate for smart WAP applications.
Abstract: In this paper, a novel planar reconfigurable monopulse antenna with compact size is proposed and studied for indoor smart wireless access points (WAPs) application. Circular polarization is achieved by using a dual-mode substrate integrated waveguide (SIW) slot antenna. Two diagonal ports are individually used to excite the SIW element antenna to achieve a 180° phase-shifting excitation. A reconfigurable $2 \times 2$ prototype is developed with the proposed element antenna, and it uses eight PIN diodes as four switches to implement the reconfiguration. Sum beams, difference beams in azimuth and elevation planes, and bidifference beams are generated. Measurement results verify the designed prototype, showing that the antenna has a null depth of over 30 dB and a peak sum beam gain of 12.29 dBi. The measured 10-dB return loss bandwidths are 5.72–5.96, 5.75–5.95, 5.73–5.97, and 5.76–5.94 GHz for the sum, elevation difference, azimuth difference and bidifference beams, respectively. And their measured 3-dB axial ratio (AR) bandwidths are 5.84–5.88, 5.86–5.90, 5.85–5.9, 5.85–5.9, and 5.84–5.91 GHz. The capability of reconfigurable monopulse beams ensures that the proposed antenna is a good candidate for smart WAP applications.

63 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023285
2022837
2021601
2020738
2019970
2018994