Wireless Powered Drone


Researchers at Imperial College London have demonstrated that they can wirelessly power a drone while it is flying. Reference [1] How wireless power charging could recharge a flying drone [2] Wireless Power Lab at Imperial College London [3] The author’s homepage


Measuring Wireless Power Transfer Efficiency (1)


Transmission efficiency of the wireless power transfer (WPT) system can be measured with a vector network analyzer (VNWA). The following picture shows how we measured the transmission efficiency of this system. The yellow WPT coil in the left side is connected to the port 1 of VNWA, while the blue WPT coil in the right side is connected to the port 2 of VNWA. The resonant frequency of this system…


Impedance matching of the WPT coil


Hello, I will explain how I matched input impedance of the WPT coil to 50 Ohm. Please look at the following picture. You can see that SMA cable is directly connected with the feed coil. Let’s see the frequency characteristic properties of this WPT coil. Frequency range is between 1 MHz and 27 MHz. So the center frequency is 14 MHz (=0.5*(1+27) MHz) that is the resonant frequency of this…


Measuring Lumped Elements Values for WPT coil


Hello. I will explain how to measure and  decide  lumped elements values for WPT coil. Here is the WPT coil that I made for my experiments. The WPT coil consists of a resonant coil and a feed coil with SMA connector. The resonant coil is spiral and has parasitic capacitance between the spiral lines and this capacitance make this coil resonate at LC resonant frequency. The feed coil is a…


Extraction of lumped elements parameters using VNWA


VNWA3E has special functions to extract the lumped elements parameters of circuits or some components.  Today, I will explain how to use this functions with the following 1 [nF] ceramic capacitor. First, I measured the S11 parameters and other parameters using the special tool which is designed for through-hole components.  We can easily expect that component wire produces parasitic inductance, which results in some resonance at some frequency. The following…


Z parameters of the coupled inductors network


Circuit theory is very good tool to understand and calculate the WPT system. In order to understand what happens in the magnetic coupling in circuit theory, two port network theory provides us good knowledge. Let’s start discussion with the following figure. The figure shows the schematic of the 2-port network. the 2-port network will be anything such as band pass filter, transmission line or WPT system. We can describe this…


Wireless Power Transfer Analysis using LTSpice


LTSpice can be used to calculate the efficiency and other parameters in wireless power transfer (WPT). First, We build the equivalent circuit diagram of the WPT system below. The figure and data came from the following paper. Sample, A. P., Meyer, D. a., & Smith, J. R. (2011). Analysis, experimental results, and range adaptation of magnetically coupled resonators for wireless power transfer. IEEE Transactions on Industrial Electronics, 58(c), 544–554. http://doi.org/10.1109/TIE.2010.2046002…


S-parameters with LTSpice


The .net Spice function can be used to calculate two port parameters such as Z,Y,H and S parameters. Zin and Zout can also be calculated. The circuit below shows a simple example. This is the bans pass filter (BPF). Here is the LTspice file. ltspice_sparameter   1. Create an input port V1 with a series resistance. The series resistance will typically be 50 Ohm for S-parameters. This resistance will not…