Return loss

About: Return loss is a research topic. Over the lifetime, 11090 publications have been published within this topic receiving 97603 citations.

A modified two-section UWB Wilkinson power divider

Abstract: A novel Wilkinson power divider with modification of the traditional two-section Wilkinson power divider by adding one open stub on each branch is proposed. This design method is validated by building a divider working in the UWB band (3.1 GHz - 10.6 GHz). It is better in performance, but is about 10% smaller than the traditional three-section power divider and spares one resistor. The simulation and measurement results of the modified divider show equal power split, a good insertion loss of less than 1.1 dB, a good return loss of all ports of less than - 10 dB, and a good isolation is less than -11 dB over the UWB band.

Development of a compact rectenna for wireless powering of a head-mountable deep brain stimulation device

Abstract: Design of a rectangular spiral planar inverted-F antenna (PIFA) at 915 MHz for wireless power transmission applications is proposed. The antenna and rectifying circuitry form a rectenna, which can produce dc power from a distant radio frequency energy transmitter. The generated dc power is used to operate a low-power deep brain stimulation pulse generator. The proposed antenna has the dimensions of 10 mm $\times\,$ 12.5 mm $\times\,$ 1.5 mm and resonance frequency of 915 MHz with a measured bandwidth of 15 MHz at return loss of ${-}{\rm 10}~{\rm dB}$ . A dielectric substrate of FR-4 of $\varepsilon _{r}=4.8$ and $\delta=0.015$ with thickness of 1.5 mm is used for both antenna and rectifier circuit simulation and fabrication because of its availability and low cost. An L-section impedance matching circuit is used between the PIFA and voltage doubler rectifier. The impedance matching circuit also works as a low-pass filter for elimination of higher order harmonics. Maximum dc voltage at the rectenna output is 7.5 V in free space and this rectenna can drive a deep brain stimulation pulse generator at a distance of 30 cm from a radio frequency energy transmitter, which transmits power of 26.77 dBm.

Novel Design of UWB Antenna with Band - Notch Capability

Abstract: An ultra-wideband (UWB) antenna with a narrow frequency notch is presented. The antenna has been fabricated on a Duroid 5870 substrate and occupies an area of only 30times35 mm2. Starting from a trapezoidal planar patch exhibiting a VSWR smaller than 2.5 in the 3.5-10 GHz band, a frequency notch at 5.65 GHz is introduced by two slots near the coplanar waveguide feeding the patch. The measured return loss shows a good agreement with the simulation results and proves that this kind of antenna is suitable for reducing the detrimental interference effects of WLAN, operating around 5.5 GHz, on UWB radio links.

Broadband circularly polarized stacked patch antenna for UHF RFID applications

Abstract: A broadband circularly polarized stacked patch antenna for UHF RFID application has been presented and investigated in this paper. The measured results have shown the good antenna performance with gain of more than 6.5 dBic, return loss less than -10 dB, and axial ratio less than 3 dB within the frequency range of 820-985 MHz (18.3 %). Due to the broadband performance covering the whole RFID UHF band, it is a good candidate for a reader antenna with high performance and low cost.

Frequency-Agile Patch Element Using Varactor Loaded Patterned Ground Plane

Abstract: This paper presents, for the first time, a method to realize the concept of frequency agility on patch-type circuits, which have found more applications at very high frequencies because of its simple structure. A patterned ground plane has recently been proposed for size reduction of patch-type circuits making them more favorable at lower frequencies. An additional auxiliary patch on the ground plane is proposed in this paper as a mechanism to change the capacitance between the upper patch and ground plane. The patterned ground plane loaded with tunable capacitors is applied to the patch element to realize frequency agility. For demonstration, a frequency-agile rectangular patch hybrid coupler with a varactor loaded patterned ground plane is designed to operate over a frequency range of 50% (from 1.5 to 2.5 GHz) with good return loss, small amplitude imbalance, and quadrature phase characteristics.