This means that if a sinusoidal voltage is applied at the antenna terminals with an amplitude of 1 Volt, then the current will have an amplitude of 1/50 = 0. This is quite useful when you are designing low-loss networks such. , some amount of incident power will reflect the source in a practical system). In this case, the two strings have different tensions and different velocities. Abstract. Advertisement. 0. The correct way to consider impedance matching in transmission lines is to look at the load end of the interconnect and work backwards to the source. If you have a 10 Ω resistor, 2 mH inductor, and 500 μF capacitor, the impedance is 0. This article offers an introduction to the Smith chart and how it’s used to make transmission-line calculations and fundamental impedance-matching circuits. From the S-parameter matrix, you can calculate characteristics of linear networks such as gain, loss, impedance, phase group delay, and voltage standing wave ratio (VSWR). Ohm's law is rescued. They look like an ‘L,’ though it may be upside-down. Now, imagine the driver sends out Voc 2V (the differential voltage). A copper coil of 28 mm diameter was designed in ADS layout, converted to a symbol, and used to calculate the impedance of the coil at 300 MHz. Outside the impedance bandwidth, the antenna reflects the input power due to impedance mismatch and results in poor radiation. 94dB: if we calculate the mismatch for the impedance being fed (note the reference impedance is 18. Object-orientation (OO) is the default method for business-centric design in programming languages. 5 reflection coefficient: VSWR (voltage standing wave ratio, sometimes pronounced "viswar"), is the ratio of the maximum standing wave amplitude at one node to the minimum amplitude at another node in a system. Calculation of Parasitic Depletion Capacitance • Depletion q J (v D) is non-linear --> take the worst case and use the zero-bias capacitance C jo as a linear charge-storage element during the transient. The answer can be found by using the impedance mismatch loss calculator. This is one of the fundamental tasks in getting an antenna to radiate, and hence is. H. Imped-ance is a property of a medium. CUI Devices' speaker power calculator can be used to quickly solve for a speaker’s power, voltage, and impedance ratings when two values are known. Ethernet lines are differential pairs with a differential impedance of 100 Ohms. When the differential via pair is very short, its impedance will not matter; the input impedance at the via pair will be the input differential impedance from Pair 2. It seems like the case for me, however it does not explain how to calculate the resistances. 2 into Equation 4, the mismatch uncertainty works out to MU = 0. 83% is. We can calculate the common-mode input impedance pretty quickly using the equations in the above post. The explanation is simple. 7. Depending on the size of the gap and the distance to the plane, you may see an impedance discontinuity. Normally, this equation is derived while assuming the electromagnetic wave is a plane wave, and most treatments only consider what happens between the transmission line and the load component. In radio engineering and telecommunications, standing wave ratio (SWR) is a measure of impedance matching of loads to the characteristic impedance of a transmission line or waveguide. Termination at both end nodes of a CAN bus is a necessity. − ϑ ρ ϑ − ϑ ρ χ ρ. Output Return Loss Var3. Twisted pair: qquad footnotesize ext {Impedance} = frac {120 imes ln (2s/d)} {sqrt {varepsilon_r}} Impedance = εr120 × ln(2s/d) As you can see, it is not overly complicated to calculate by hand, but it will definitely take longer than using our calculator. – The impedance mismatch between vias and signal traces can cause transmission-line reflections. As also noted in the picture, the subsequent calculations are on the: [2] top-layer single-end impedance; [3] top-layer differential impedance; [4] inner-layer differential impedance. The correct way the calculate power transfer is to calculate Rho, the reflection. g. VSWR (pronounced "viswar"), or the Voltage Standing Wave Ratio, is the ratio of the maximum standing wave amplitude at one node to the minimum amplitude at another node in a system. First, if we have a common-mode voltage source the input impedance it "sees" looking. Microstrip impedance calculator Mixer spur calculator mmWave Link Budget calculator Noise Figure/Temp converter Optimal Mitre calculator Path loss calculator Phase Noise to Jitter converter PLL PFD Frequency calculator PLL loop filter calculator Potential divider calculator Propagation time calculator Gamma to Impedance converter Reactance. LC Impedance matching network designer Enter the input and output impedances to be matched and the centre frequency. One of the benefits of the bass combo is that you don't. 2. This is consistent with the peak-to-peak variation of the power curve in Figure 4. For instance, a return loss of 20 dB translates to a VSWR of ~ 1. The next graph investigates this further. 05+j51. 011. In figure (b), a two-port network was inserted between them. Switch on your low-frequency generator, set it to 1 kHz (or use the audio output of your PC), add a 1-kΩ resistor to emulate a high-output impedance, and connect a 4-Ω loudspeaker. In electrical engineering, impedance matching is the practice of designing or adjusting the input impedance or output impedance of an electrical device for a desired value. However, I have a bit of a length mismatch between the TX+/TX- and RX+/RX- pairs (about 5mm). To quantize the RF losses in transmission lines we need to calculate the attenuation constant , which is in the "natural" units of Nepers/meter. ,100 % power transferred from a source to a load via a transmission line/cable). As both these parameters are similar, they can be interconverted. dB is recommended because improving the S11 value further than –10 dB will only improve the mismatch loss by a minimal value i. If you need to calculate a transfer function from S-parameters, read our guide to learn more. ZP= ZS x (Turns Ratio)2. Impedance is an important parameter to characterize electronic circuits, components, and materials used to make components. Impedance matching provides a dual role of enabling power transfer into a load by suppressing reflections. Figure 3. Calculate. Further calculator information is available in About our calculators. Where, RL = Return loss in dB. The fundamental principle of RF impedance matching is to design and place an impedance network which removes any impedance mismatch present in the circuit. At GHz frequencies, accurate inductor models that include parasitic elements are necessary. In electrical engineering, impedance matching is the practice of designing or adjusting the input impedance or output impedance of an electrical device for a desired value. Here almost 80% of the power is reflected while only 20% is transmitted forward. 2017 Return loss and impedance Detail: comment 30, KRn receiver differential input return loss • Now that COM is defined with a near-neutral termination and package impedance, receiver mismatch is the receiver designer's concern, not the standard's, unless it is very extreme, because the receiver interferenceVSWR varies from a ratio of 1, indicating a system with no impedance between components, to an absolute mismatch where VSWR is anything up to ∞. Impedance mismatch. This formula allows you to calculate impedance when the reflection coefficient is known, quantifying the impedance. If Z = 0 Z and ZL = ZG (for real GZ) we have a matched load, maximum available power goes into the load i. Mismatch can be specified as: the impedance at the load end of the line;Installer for the Windows version of dB Calculator. It supports both balanced and unbalanced lines. Suppose our unmatched load impedance is Z = 60 - i35 Ohms; if the system impedance is 50 Ohms, then we divide. Speaker wire size quick guide. Your relay is single line with characteristic impedance of 50 Ohms. In an attenuator, it is a measure of the deviation from 50 or 75 ohms of the component’s input and output impedances. This paper review the different meth - ods used to calculate the input impedance of microstrip patch antenna along with different impedance match-ing techniques. e. It is defined as the ratio of the standing wave amplitude measured at maxima and minima along a transmission line. If this is the case, then 100dB(μV/m) 100 d B ( μ V / m) means that. In contrast the Klopfenstein taper derives the required impedance profile for a source and load impedance mismatch ratio ((Z_{L}/Z_{S})) and (Gamma_{m}). — Advertise Here —. Critical length is longer when the impedance deviation is larger. An impedance mismatch in a circuit or along a transmission line will produce a reflection back to the source of the signal. Using v= T. The problem lies in neither relational nor OO, but in the. You can reproduce it easily. Broadband Impedance Matching with Transformer; Ferrite Toroidal Coil (Amidon) Helical Coil Calculator; Impedance Calculator : XL, XC; Iron Powder Toroidal Coil (Amidon) Due to the impedance characteristics of different components, you may not be able to match impedance throughout the amplifier design. In figure (a) a generator with impedance ZG is hooked up to a load ZL. 7. This online reflection coefficient calculator calculates the reflection coefficient (Γ) by entering the value of the characteristic impedance Z o (in ohms. tuning. [2] Calculate the top layer signal end impedance: Two tools are giving Zo=48 and Zo=47. Transformed through the antenna side capacitor (adjusted to 139. Vinamra [ 10 ] studied the plate impact problem on layered medium by tracing all the ways propagating in the system and solving them to. Part 2. But due to antenna bandwidth constraints such as those posed by wideband antennas such as LTE, a lower limit of 6 dB is the commonly. Since the impedance is a real number, the voltage is in-phase with the current. But it is possible to select any other base if the operator chooses so. Fig. In a 50-ohm system, each output would be connected to a 50-ohm impedance, thus offering a 25-ohm impedance to the input port. Now, consider a driver (RS422) connected to a reciever. It can also be thought of as the amount of power gained if the system was perfectly matched [dubious – discuss]. 295-49. realizable impedance values by simply observing the unit circle. Simple circuit showing characteristic impedance Z o and the. 9 Ω and a positive imaginary part (+j99 Ω) to ensure maximum power transfer will be achieved. It also gives. At 0. As a result of this mismatch, only 4% of the incident power is reflected back, while 96% is transmitted forward. The solution is simple: choose a standardized impedance that can be used in numerous RF systems, and ensure that components and cables are designed accordingly. In addition, the values of speaker impedances listed on the back of speaker boxes. edu. This calculator computes the VSWR, reflection coefficient, return loss and matching loss in a transmission line. 1 Return Loss. To calculate the impedance, I use Saturn PCB impedance calculator software, Inc - PCB Toolkit V8. Here, the impedance is most closely matched at ~445 MHz and S11 remains pretty flat over a ~200 MHz bandwidth, which is consistent with the power data shown in the graphs above. Whether the reflection reduces the signal reaching the load depends on how it interferes with reflections from other mismatches or components in the system. 3. 3d)pF. Relation of resistance and impedance in determining bypass capacitor size. When the load impedance is mismatched to the source in a 1 : N imped-ance ratio, a 1 : N impedance ratio transformer is required. VSWR Calculator. Microstrip construction consists of a. To calculate PLF, let Pr be the power received by an antenna and Pi be the. Microstrip Stripline . Microstrip impedance calculator Mixer spur calculator mmWave Link Budget calculator Noise Figure/Temp converter Optimal Mitre calculator Path loss calculator Phase Noise to Jitter converter PLL PFD Frequency calculator PLL loop filter calculator Potential divider calculator Propagation time calculator Gamma to Impedance converter Reactance. Clearly, the power reflected back from the antenna to the source should be minimized as far as possible. However, RF circuits use multi-section and tapered transformers to match impedance. The most serious problems occur when the impedance of the load is too low, requiring too much power from the active device to drive the load at acceptable levels. The higher the VSWR, the worse the match. By shorting the voltage source, we calculate the Thevenin’s equivalent impedance of the circuit as shown in figure. The answer can be found by using the impedance mismatch loss calculator. 3). By looking at the maximum and minimum voltage amplitude of the standing wave, we can calculate the VSWR. In the above example, the obtainable gain improvement is 0. Disc Air Capacitor Calculator; Impedance Calculator : XL, XC; Inductors, Transformers. com . LC Impedance matching network designer Enter the input and output impedances to be matched and the centre frequency. Stripline Impedance calculator Smith charts VSWR/Return loss converter Wavelength calculator Wilkinson splitter designer. EIRP (Effective Isotropic Radiated Power) is the measured radiated power of an antenna in a specific direction. It does not account for the fact that SWR measured though a lossy (i. This reduction of signal, also called attenuation, is directly related to the length of a cable—the longer the cable, the greater the insertion loss. It is useful to get the approximate value of the required. different impedance, like 75 Ω if required). In the pair with larger spacing (10 mil), a 21 mil amplitude length tuning. But, for a practical system, there will be always a small impedance mismatch. D is the center-to-center distance between the signal and the ground via, and a is the radius of the via. Moreno López, Artur A. 7. 0. González Hernández, Ana I. A perfect match is represented by a VSWR of 1. Mediums in which the speed of sound is different generally. g. Keywords: Aerodynamics; building codes; micrometeorology; statistics; structural dynamics;M. The RF budget analysis measurements will be performed 0 to 0. 46 dB. 30 MB. 2), you will lose almost 4 dB (red line). In the pair with larger spacing (10 mil), a 21 mil amplitude length. The shape of the reflected wave is also valuable since it reveals both the nature and magnitude of the mismatch. Reflection coefficient and return loss are two key parameters that determine the impedance mismatch in any RF signal transmission. Isolation Var6. In one typical RF application, VSWR is used to measure the amount of reflection due to impedance mismatch. 2%) = ±3. The VSWR is a figure of merit for impedance match (or mismatch). Thus, it gives us the total variation in the load power. Tuning for your traces to the desired impedance value occurs by adjusting trace width and distance from the reference plane. e. In this case, according to the calculation formula of input impedance, by inserting a quarter wavelength odd multiple length transmission line, also called impedance converter, between the transmission line and the load, the gap between them can be further narrowed and the impedance matching can be approached. Some of the impinging energy will reflect to the source, with the amount dependent on the magnitude of the mismatch (Figure 2). Hence, signal quality is maintained. In this situation, a matching network is used to match the antenna, including its feed line, to the impedance of the source. Differential. Return Loss and Mismatch Loss Calculator Calculates the absolute load impedance, reflection coefficient, VSWR, return loss and mismatch loss of a load. 6 ohm load. The capacitance of a parallel plate capacitor is given by C= (kA/11. The base can be directly driven by the voltage output of the I. signal reflections due to impedance mismatch compromising signal integrity. Or use a L_pad. In the case of a 6 dB return loss, this is equivalent to 0. Any mismatch loss is rolled up in the calculation. In DC circuits, the source and load should be equal. As both these parameters are similar, they can be interconverted. Those pairs connect via a dedicated FFC cable. Its expression has been defined as follows: Because the impedances are complex numbers, the reflection coefficient will be a complex number as well. The magnitude of the ripple will depend upon the severity of the impedance mismatch at the interface, and the period of the ripple over frequency will. This calculator computes the matched line loss for a transmission line using a model calibrated from data for the transmission line types built in to the calculator. A ringing-like reflection waveform is only possible if the source and load reflection coefficients have opposite signs, and is only significant if the product of the two is close to 1 (otherwise it damps out rapidly) (Fig. 4 GHz (radar systems. The following formula relates the return loss and VSWR. Microstrip impedance calculator Mixer spur calculator mmWave Link Budget calculator Noise Figure/Temp converter Optimal Mitre calculator Path loss calculator Phase Noise to Jitter converter PLL PFD Frequency calculator PLL loop filter calculator Potential divider calculator Propagation time calculator Gamma to Impedance converter Reactance. 009. Those pairs connect via a dedicated FFC cable. A wealth of transmission line parameters can be expressed in terms of of these four lumped elements, including characteristic impedance, propagation constant and phase velocity. Background S11 is the input reflection coefficient with a. The model is excited by lumped port (0. impedance of antennas, coaxial cables, and filters, etc. This article explains the basics of radio frequency (RF) impedance matching, how to calculate the matching components, and how to check the results in LTspice ®. Gain Var5. Impedance (Z) is a measure of the opposition to. 6c). Let's match the impedance of the same signal since differential pair routing is completed when the impedance is matched properly. 18 dB. Using VNA I measured S11 it is -53. The ringing-like behavior is caused by an impedance mismatch. berkeley. 8. Return loss vs. 64% or ±10 x log10 (103. 3: impedance mismatch at the input. This can result in issues like ringing or impedance mismatch, resulting in interference or inadequate power transfer. Now, if I understand it correctly line A if more positive than line B, then the reciever outputs a logic. This calculator converts the SWR across an impedance mismatch to loss. VSWR (pronounced "viswar"), or the Voltage Standing Wave Ratio, is the ratio of the maximum standing wave amplitude at one node to the minimum amplitude at another node in a system. Emphasis is on S-parameters as design tools. If we substitute Γ 1 = Γ 2 = -0. Mismatch can be specified as: the impedance at the load end of the line; Installer for the Windows version of dB Calculator. As a result of this mismatch, only 4% of the incident power is reflected back, while 96% is transmitted forward. Length-tuning structures and their effects on impedance. Now you have a measurement of how "lossless" a circuit would be if you were able to perfectly impedance match it. 3cd Sept. Enter VSWR: Calculate! Reflection Coefficient. In the context of databases, impedance mismatch refers to the discrepancy. This impedance mismatch can be with a device inserted in the line or with the terminating load. These are primarily the result ofThe Differential microstrip impedance calculator is used to compute the differential (Zd) and single-ended impedance (Zo) of an edge-coupled microstrip line just by entering the width, separation and thickness of the trace along with the dielectric thickness and constant of the coupled line. 398Ω. In order to properly get right cascaded S21 from the Sxx of each individual block you have to take into the impedance mismatch loss into account, which includes. 04 dB when the S11 value is –15 dB or –20 dB respectively. The refection coefficient due an impedance mismatch is: - $dfrac{R-Z_o}{R+Zo}$ Where Zo is the impedance of the. This is a nice example of an impedance mismatch problem. When a signal reflects, the power transferred downstream towards a load is reduced. So rather than setting impedance for every different frequency, the manufactures set the nominal impedance for a speaker, which is calculated from the lowest values of the impedance of that speaker, and mainly their average is set as the impedance. VSWR Calculator Here's a simple VSWR calculator. At the Deembed setting there, thick the box "deembed", and key in the distance. Solution At the design frequency, the impedance looking into this section of line from the emitter should be equal to that of a 2. Impedance mismatch doesn't cause attenuation per se, it causes reflection. However, S11 is still quite high (minimum of 0. Higher VSWR implies a higher mismatch. 5)2= 500Ω. ZL =. This is impedance matching, and the optimal value is R = R IN. 0. If you can't remember in which order the numerator is subtracted (did we just say "Z L-Z 0" or Z 0-Z L "?), you can always figure it. Most RF systems are built around 50 Ω impedance. Even and Odd Mode Impedance. With the expressions for VO± from before and some algebra, an equation to calculate the output impedance of the circuitTwo 8 ohm cabs connected to your amp will present a 4 ohm load. Shock impedance mismatch calculations using A l 3 L i. If we substitute Γ 1 = Γ 2 = -0. Part 1. VSWR Mismatch Errors: Both amplitude and phase errors are introduced when mismatched impedances are present at an electrical interface. 3), we can think of a transistor as a non-linear voltage-to-current converter having an exponential characteristic. The formula for S11 treats the transmission line as a circuit network with its own input impedance, which is required when considering wave propagation into an electrically. Clearly, the power reflected back from the antenna to the source should be minimized as far as possible. Enter Zo - source characteristic impedance in Ω S11 - either linear or dB value can be used The tool will calculate the absolute value of the load impedance ZL in ohm. Figure 6 shows four typical oscilloscope displays and the load impedance responsible for each. Routing to pins, pads, components, and BGA breakout routing should be symmetric and length matched, with length tuning/mismatch applied near the source end of a link. 9 ohms of effective speaker load no matter the impedance of your headphones, even with three sets of low impedance headphones used simultaneously. 3 watts to 5. 2) specifies the far-field impedance of an electromagnetic wave in air to be 377 Ω. While Ohm's Law applies directly to resistors in DC or in AC circuits, the form of the current-voltage relationship in AC circuits in general is modified to the form:. Rematching the load will increase it further still. The coupling of waves between the piezoelectric generators, detectors, and propagating media is challenging due to mismatch in the acoustic properties. This practice is called impedance matching. Impedance matching: In high-speed digital applications, several data lines run at tens of Gbps, leading to impedance mismatch due to parasitic capacitance and inductance. Perales Perales, Yuliang Wu andThe input impedance of a transmission line with arbitrary terminating impedance is zL = ZL Z0 0 = zL − 1 zL 1 = ∣ ∣ e j L = 2 f c r = 2 r Z ¿ = Z0 1 e −2 j L 1− e −2 j L We will use the Smith Chart to ease the calculation of this complex quantity. Under the Frequency Analysis tab in Default System Options you will see that a frequency range relative to the center frequency of the system has been defined. For example, the THS4509 performs best with R F in the range of 300 to 500 W. calculation procedures that can be incorporated in standard provisions can contribute significantly to the reduction of losses in strong winds, and of materials and embodied energy consumption. Voltage Divider Calculator 1 (Fixed) Voltage Divider Calculator 2 (Adjusteable) Capacitors. I always try to tune my pcb antennas in length, so they operate in resonance, by cutting the antenna with a scalpel and then matching the tuned antenna to the transmitter. It is defined as the ratio of the standing. Relation of resistance and impedance in determining bypass capacitor size. The source impedance driving port 1 must be 50Ω, and the load impedance presented to port 2 must also be 50Ω. Impedance mismatch in a circuit can be caused by a number of factors. Click here to go to our main page on S-parameters. Click here to go to our page on VSWR. This is why a low impedance mismatch can sound better than a perfect amp-to-speaker impedance match. Propagation delay (t pd) in PCBs is the time taken by a signal to travel through a unit length of a transmission line . The mismatch of a load Z L to a source Z 0 results in a reflection coefficient of:. , load, source). But, for a practical system. Within the impedance bandwidth, the antenna is useful. With the Mismatch Losses box ticked the calculator will return an attenuation. The inductance, L, of one via pair calculates to:. Impedance mismatch leads to a large portion of electrical energy reflected back to the excitation source, especially in large aperture and high-frequency ultrasonic transducer. In effect, by choosing a source reactance that is equal but opposite to the load. e. Instructions. Inside the length tuning section, we have something different. TI HDMI Design Guide June. In fact, the apparent contradiction in the definitions of a reflection coefficient and conjugate matching in the maximum power transfer theorem arises due to the way in which wave propagation is defined in the original formulation of S-parameters. where I and V are the rms or "effective" values. the impedance mismatch, which should be minimum to satisfy the desirable maximum power transfer theorem. By entering the reflection coefficient, the return loss can be computed using this calculator. Note that the S-parameter is basically the magnitude of the reflection coefficient, which depends on the antenna impedance as well as the impedance of the VNA, which is typically 50 Ohms. Click. , real) cable will always. 3pF) in the tuner to 111. It is a natural phenomenon that occurs for any type of transmission—whether it's electricity or data. Develop a two-element matching network to match a source with an impedance of [Math Processing Error] Z S = 12. However, getting an accurate interconnect impedance calculation is the starting point for ensuring accurate signal transfer between a driver and receiver. ; de Souza, C. Requires Windows 7 (64 Bit) or higher. The relationship between impedance mismatch and reflection can be visualized on a Smith chart. Hence, the return loss is always lower than the ideal system (i. Source and load impedance circuit. VR V R and IR I R reflections have an impedance ratio of (exactly) 50 ohms hence, they are compatible to flow back up the 50 ohm cable to the source. But in the end the calculation for real complex impedance has to be doneIn general, to measure an output impedance, you just connect a known impedance across it and measure the drop in voltage level. I have done the impedance calculations to figure out the track geometry needed for 100 ohm differential impedance and confirmed it with the board house. For a transverse-electric-magnetic ( TEM) plane wave traveling through a homogeneous medium, the wave impedance is. Impedance matching is an important part of RF system design; however, in practice there will likely be some degree of mismatch loss. Components based on GaN are best for emerging areas of RF. Table of Contents show. Primary turns, N P: 500. 13dB, again another almost perfect match to the measured values. BUT, output stages are like power supplies. 8. 49 dB and 17 + 0. I need to measure Z line impedance. 707. Often,. Stability, impedance matching and general amplifier design are covered. If the impedance of the load matches that of the source, impedance matching is not required, and the balun has a 1 : 1 impedance ratio. To be more clear, consider a simple RF circuit consisting of source and load connected via transmission lines. EIRP Calculator. Zis known as an impedance. Assuming the systems have no internal loss. This is due to the very short wavelengths of mmWave frequencies (see below). Impedance matching is an important part of RF system design; however, there is always be some degree of mis-matchlossinpractice. Impedance matching is designing source and load impedances to minimize signal reflection or maximize power transfer. 5 GHz are due to the impedance mismatch. The Reflection Coefficient can be calculated from return loss by using the following formula. 05 that is free software and very famous among designers. If the power incident on a load is Pi P i and the power reflected by the load is Pr P r, then the return loss in decibels is [6, 7] RLdB = 10 log Pi Pr (2. The VSS Modeling Guides provides more information on impedance mismatch modeling in VSS. Thus, the impedance looking into the common or input port would present a mismatch in a 50-ohm system. This means an electric filed intensity expressed in dB relative to 1μV/m 1 μ V / m (one microvolt per meter). Losses In Transformer:. This calculator computes the matched line loss for a transmission line using a model calibrated from data for the transmission line types built in to the calculator. When the via pair is very long, such as in a thick backplane, the differential pair via impedance will determine impedance mismatch seen by a propagating signal. 1, for system 2 is 0. A power sensor with a return loss of –23 dB is connected to a calibration source with a return loss of –20 dB. Using VNA I measured S11 it is -53. Extron Audio Calculators. 2GHz offset from the center. Use this calculator to get the value of mismatch Loss from the reflection coefficient. The relationship between impedance mismatch and reflection can be visualized on a Smith. But when I use the BNC cable connects to the FG, and the scope cable connect to the scope I got 2Vpp output with the same input. 009.