The attenuation per unit length (basic loss) in a coaxial cable (dB/m) at radio frequencies can be approximately determined by the formula: k2 — factor, characterizing the loss in the dielectric of the internal insulation, proportional to the frequency. The RG-63/A/B/U is a 125-ohm coaxial cable with an overall diameter of 0. 336: 360 = 0. R = l σA R = l σ A. 3pF) in the tuner to 111. The calculator allows you to make an approximate calculation of the characteristic impedance of a microstrip transmission line, provided that the line. Now, let us investigate the physical meaning of return loss. it has double shielding, outer layer is stranded/woven wires, inner layer is metal strip wrapped in spiral, PTFE look alike. UsefulFormulas. DS3 & DS4 Cable. 10. 15 mm (0. 854187817620. In the limiting case of infinite load impedance, theBecause a coax operates in TEM mode — with the electric and magnetic fields normal to the direction of propagation along the cable — modeling a 2D cross section suffices to compute the fields and the impedance. Coaxial characteristic impedance calculator. 25 inches. This is the only way to calculate the total impedance of a circuit in parallel that includes both resistance and reactance. Conductor DCR Nom. 850c-0. i cant find the datasheet though it has part number 473-872-03 Rev A1 Mfr 64023. Coaxial cable characteristic impedance Calculator and formula. TF-047; SF. The distance in time between adjacent pulses is 35. This tool will help you find the inductance for a given length of coax cable. So, if the Propagation Velocity is 70%, it means that the signal. Linkedin. This coaxial cable calculator determines the distributed capacitance and inductance of a coaxial cable, its impedance and cutoff frequency for a given cable geometry, and relative permittivity or velocity factor. λ = Wavelength. 2. Fiber calculators and tools. A little more generally, a quarter-wave section of transmission line of impedance Z 0 converts between two impedances Z a and Z b: Z 0 / Z a = Z b / Z 0. × 10 −12 F/m is the. In the limiting case of infinite load impedance, the Because a coax operates in TEM mode — with the electric and magnetic fields normal to the direction of propagation along the cable — modeling a 2D cross section suffices to compute the fields and the impedance. Impedance per unit length (Z) Ω. 240 DIA) Solid Copper center conductor Foam Polyethylene Dielectric Aluminum Tape outer conductorBoth of the cables are inside a bigger one: The black part is the isolation. As such, the outer (braided) conductor completely. 84. The formula is this: -. The nice part about coax is that it can be bent and flexible unlike most pcb transmission lines. Since we might as well find the impedance per length, we can study the expression: Rl = 1 σA R l = 1 σ A. Hence, the return loss is always lower than the ideal system (i. Find a length of coaxial cable and bring it with you to class for discussion. c is the speed of light 299,792,458 m⋅s −1,. The VSWR/return loss calculator from Pasternack will find VSWR, return Loss, mismatch loss, and the reflection coefficient given any one of the listed input types. WR90 Specifications. Example: Calculate the distributed capacitance and inductance, impedance and a cutoff frequency of a coaxial cable RG-58 with the following characteristics: inner conductor diameter 0. 398Ω. The following formula relates the return loss and VSWR. Ns = Number of turns in Secondary coil. 191Ω. 15 mm (0. (D) is the outer diameter of coaxial. 295-49. Then use the LCR Meter and measure the inductance at the open end of the cable. the combined velocity factor will be around 0. When a coaxial cable is constructed using two concentric dielectrics as shown above, the wave propagation is no longer purely transverse-electromagnetic (TEM), as in the single-dielectric coax, but. 80 for typical two-wire lines and coaxial cables. What is the characteristic impedance of twisted pair cables? 100 ohms. Where we basically use the effective area instead. Kenneth L. By inputting the necessary values into the. 85419 x 10. Next up is the inductance. The coaxial cable, along with the balanced two-wire, is the most common type of transmission line used in RF communications. 15 mm (0. 36Ω), the impedance is: Transformed through 25 feet of RG-8 coaxial cable to 111. The calculator will calculate one possible solution for a Single Stub Match that you can implement in your antenna system. 66 and 0. Suitable for VHF (~1. A Rectangular Waveguide is a conducting cylinder of rectangular cross-section used to guide the propagation of waves. 4w to achieve 100w at the aerial. Cable Inductance. With the conductor sizes (diameter of the inner and outer conductors) and relative permittivity as parameters, this tool calculates not only the coaxial line impedance but also the capacitance and inductance per meter, the RF cutoff frequency and the length of a 1/4 wave transformer sub taking into. 5 mm Coaxial Connector is designed to be relatively rugged. Co-axial cable. 0. Coax Inductance Description. The characteristic impedance of coaxial cable can be determined from the formula: ZO is the Characteristic Impedance ZOC is the Open Circuit Impedance. Example: Calculate the distributed capacitance and inductance, impedance and a cutoff frequency of a coaxial cable RG-58 with the following characteristics: inner conductor diameter 0. N-Way Power Divider Calculator. The inner and outer. The coax cable has a capacitance as a result of the gap between inner conductor and outer shield of the cable. The 3. ε 0 = 8. Outer diameter of the co-axial cable (D) Inner. Geometriy is not that critical. 3. The impedance is maintained so long as L/C is maintained. εr = Dielectric constant of the insulator. Coax Conn Rx Cable and connector impedance The characteristic impedance of a cable and its connec-tors should match the impedance of the transmitter and receiver. See Figure 2. Where: Z = the 1/4 wave coax line impedance, Zr = terminating resistive impedance (antenna) ( input resistive impedance as read on the RF impedance bridge at the end of the 1/2 wave line). Coaxial cable characteristic impedance Calculator and formula. ε0 = permittivity of free space = 8. Where L is the length of the dipoles. Wi-Fi 7 will enable consumer, enterprise, Industry 4. , some amount of incident power will reflect the source in a practical system). For discussion of impedance matching of the voltage source to the transmissionJul 22, 2019. c is the speed of light 299,792,458 m⋅s −1,. If the source is a DC source, a current, I, flows down the center conductor, through the load, and back to the source via the outer conductor. The second problem is. 8 MHz needs a coil of 18 µH. 124 in), type of insulation is polyethylene with the relative permittivity of 2. Calculator (1) computes that a reactance of 200 Ohms at 1. First remove the coax outerExample: Calculate the distributed capacitance and inductance, impedance and a cutoff frequency of a coaxial cable RG-58 with the following characteristics: inner conductor diameter 0. 850c-0. These two cables will transform the impedance for maximal power transfer. e. In an RF system, when power is sent from the source to load, there are three main parameters to be considered: (1) incident power. For the cost, ladder line has lower loss than coax. D (inches) d (inches) for a typical polyethylene-insulated cable. The waveguide width determines the lower cutoff frequency and is equal (ideally) to ½ wavelength of the lower cutoff frequency. A coax loss calculator is an essential tool for network planning that helps in calculating attenuation and choosing the right coaxial cable for your network. VSWR (voltage standing wave ratio, sometimes pronounced "viswar"), is the ratio of the maximum standing wave amplitude at one node to the minimum. 0. An example of a wire microstrip might most often be found in prototypes or reworked boards where a wire is used over the top of pcb or copper clad material. Wilkinson Power Divider Calculator. Polar or rectangular grids only allow direct reading of S11. The calculator will calculate one possible solution for a Single Stub Match that you can implement in your antenna system. This will also provide the time delay the cable provides for a signal and also the capacitance and inductance per. D is the outer diameter of the cable. Maximum Operating Voltage (Vrms) 4000. Our RF and microwave calculators and converters will provide the figures you need for your radio frequency engineering needs. . 2,210. Coaxial Cable Calculator. The capacitance of a one conductor shielded cable is given by the formula below: Where: C = Total capacitance of the cable (microfarads) I charge = Charging current of the cable. 0 at Check Nearby Stores. Most professional engineers and technicians will never have the need to calculate the capacitance, inductance, or impedance of a coaxial cable since they are usually. The most commonly used twisted pair cable impedance is 100 ohms. The length of the cable makes no difference whatsoever in regard to the characteristic impedance. Semi-rigid coax (new for June 2021!) Triax (new for August 2023!) Coax cable vendors . The inductance of this structure is of interest for a number of reasons – in particular, for determining the characteristic impedance of coaxial transmission line, as addressed in Section 3. The coaxial cable, along with the balanced two-wire, is the most common type of transmission line used in RF communications. Simply select the quantity of convergence points, adjust the length and select the cable from the menu to create a bill of materials will be generated - showing the minimum amount of items required to configure a system. Instructions – Scenario 1 – Measured capacitance and inductance values. 854187817620. Coaxial Cable Impedance Calculations: USB Cable impedance: Transfer impedance of the cable. 1: Coaxial line: (a) with inner an conductor of radius a and an outer conductor with inside radius b; and (b) with cylindrical coordinates used in calculation. HELP. . It is widely used for data communications and telecommunications applications in structured cabling systems. A Rectangular Waveguide is a conducting cylinder of rectangular cross-section used to guide the propagation of waves. Coax Impedance Calculator. “Inductance Calculations” , F. These helpful formulas can be used to calculate expected phase change of Dynawave coaxial cables for any given temperature range, as well as for an array of uses for cable assemblies. Note that these calculations are theoretical and engineers and technicians will probably never have the. U. 405 inches and a voltage rating of up to 1000 Vrms. This coaxial cable calculator determines the distributed capacitance and inductance of a coaxial cable, its impedance and cutoff frequency for a given cable geometry, and relative permittivity or velocity factor. This calculator is able to calculate the impedance, delay, inductance, and capacitance of a coaxial cable. ) using the high and low frequency approximations. ε0 = permittivity of free space = 8. The ferrites are held in place by foam tape. RG178B/U part number from Pasternack is a RG178 coax cable that is flexible. pr is the relative permittivity of the material the cable is made from. The Pi attenuator consists of one series resistor and. Calculation method of the triaxial b method transfer impedance value: where a means = 20log 10 (S 21) represents the measured attenuation loss, a cal represents the composite loss. In a nut shell the characteristic impedance of a coax cable is the square root of (the per unit length inductance divide by the per unit length capacitance). “468” is the constant used to convert frequency in MHz to feet. FL connector I have a 2" microstrip transmission line to the RF input of my GPS receiver. × 10 −12 F/m is the. This causes an impedance mismatch at each staple location resulting in micro-reflections. . 15 mm (0. It has an inner 7-stranded bare copper. Both components receive a current simultaneously, generating a magnetic field. Coaxial cable is typically rated to operate at 50 or 75 ohms so the scale should be at or greater than these ratings. 4. If the cable is 50 ohms it means that the impedance driving the cable must be 50 ohms and that the termination impedance at the output of the cable must also be 50 ohms. RF Attenuators are components that reduce the amplitude level of an incoming signal. thus a big transmission line can have the same impedance as a small transmission line if one is scaled in proportion from the other. Terminating the cable with a 50 Ω resistor still causes a negative reflection , although of much smaller pulse height (Figure 5). 854187817620. d is the diameter of the inner conductor of the coax cable; units of D and d must be the same,. While commonly constructed using printed circuit boards, this structure can also be built using other materials as long as there is a conductor separated from. For any cable type, it is equal to the reciprocal (1/x) of the square root of the relative permittivity of the cable’s insulation. Where: Zo = Characteristic impedance in ΩDistributed Inductance (L') For a coaxial cable, the inductance per unit length L' in henries per meter (H/m) is defined as. The cable input. 1. Attenuation (dB/100 ft , @ 400 MHz). This relation is also the case for finite transmission lines until the wave reaches the end of the line. The input impedance of such a dipole is typically less than 50 ohms and may have a reactance. 0815 × W × V (velocity factor of the cables). This connection steps down the high antenna impedance to. 9 mm (0. ) using the high and low frequency approximations above for Rc and Lc. æ k s /), is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric (insulating material); many coaxial cables also have a protective outer sheath or jacket. The device output impedance is usually low at high power levels; so, to match this impedance with a standard 50-ohm load, coax-ial-line transformers with specifiedThe cut-off frequency of the coaxial cable represents the maximum upper operating frequency of the cable. A coax is a common transmission line construction and most rf cables are coax. Now we can add the resistances from the inner and outer shell since they're in series. It supports both balanced and unbalanced lines. D is the inside diameter of the coax cable shield,. MEDIUM VOLTAGE SHIELDED CABLE PARAMETER CALCULATOR. c is the speed of light 299,792,458 m⋅s −1,. . 39 ohm line, cut for the frequency of operation (between the antenna and your cable) you'd end up with a perfect match. In the application, the reverse calculation is also available, finding the width and length of the strip according to the given characteristic impedance and the electrical length of the T-line. Here it is: For outer diameter D, inner diameter d, and eccentricity c: Z0= [60/sqrt (ER)] x acosh [ (1/2)x (D/d+d/D-4c^2/ (dxD)] We entered the equation into Excel, and sure enough, if c=0 you get the same exact impedance you get from the. Location. Any other impedance at the output causes an impedance transformation because the SWR is not 1:1. The choke balun usually does the same thing as a regular 1:1 current balun but adds the high impedance path to the common mode currents too. ε 0 = 8. Coax Inductance Description. Attenuation (dB/100 ft, @. After all, if there is a mismatch of the antenna with this cable, the signal will be reflected before it enters to the cable. where. In fact, striplines often make components such as band-pass filter's more accurately, with more symmetric roll-off and no lower cutoff frequency. e. 16 mm]The loss tangent introduces a "real" conductance which is calculated from the susceptance by multiplying by loss tangent. DUT (cables and connectors), inaccuracy could be a prob-lem. For example, in a vacuum, the velocity of propagation would be 100% or 1 (depending on how it is represented). Zp= Input/Primary impedance. 5 to 21. 20 to 12. This CalcTown calculator calculates the capacitance, inductance, impedance and various other parameters related to a dual dielectric coaxial cable. Coaxial cable is a two-conductor cable made of a single conductor surrounded by a braided wire jacket, with a plastic insulating material separating the two. Conformable Cable. Explore the Coaxial Cable Calculator, a handy tool for calculating various parameters of coaxial cables such as impedance, capacitance, inductance, and cutoff frequency. D is the inside diameter of the coax cable shield,. CST Cable Studio generates equivalent circuits from the cable harness based on classical transmission line theory. Micro-coaxial cables. On the two smaller coils, a small piece of heavy cardboard holds the coax in. Calculate the impedance of a coaxial transmission line. You can calculate it with the following equation: Z (z) = V (z)/I (z). Wireless Converters and Calculators. Velocity of Prop. ε 0 = 8. To use the calculator you first need to measure the impedance (resistance + reactance(j)) of your antenna, this can be done with an antenna analyzer (i. for chosen frequency. When attaching a 200 Ω balanced antenna to a 50 Ω unbalanced (coaxial) cable, connect the high impedance (200 Ω) balanced antenna to the high impedance side of the transformer, and the low impedance (50 Ω) unbalanced end to the low impedance side of the transformer. A rectangular waveguide is commonly used for the transport of radio frequency signals. The Smith Chart achieves this by superimposing a grid on S11 that maps load impedance. CRA Calculator. Frequently, it becomes necessary to match. We have now proven by measurement that the LOAD Termination, Signal Generator and Coaxial Cable all have. Now, to calculate the necessary line length: assuming that our cable has a velocity factor of 0. The example structure is a standard RG6 coaxial cable. Generally, a wave is reflected back. I leave it to other sources to provide the complex equations needed to precisely model coaxial cables. Zc = characteristic impedance of cable-above-ground transmission line. Figure 2 - Fast pulses measured at the end of the coaxial cable using an oscilloscope without impedance matching. For example, if you wish to input "25000000", just type "25M" instead. d is the diameter of the inner conductor of the coax cable; units of D and d must be the same,. RF calculations and RF conversions include metric-standard, link budget, coax cable, power, attenuation, frequency and many more. 854187817620. Coax Conn Rx Cable and connector impedance The characteristic impedance of a cable and its connec-tors should match the impedance of the transmitter and receiver. The 50 ohm characteristic impedance of my coax is only "characteristic" if it's terminated with $ 50 + 0j$ load. 8 ns. where. Line Type: Belden 8215 (RG-6A) Belden 8237 (RG-8) Belden 9913 (RG-8) Belden 9258 (RG-8X) Belden 8213 (RG-11) Belden 8261 (RG-11A) Belden 8240 (RG-58) Belden. 035 in), outer conductor diameter 3. Martin and Mendenhall (1984) proposed to use an addi-tional braid (i. The entry unit of frequency can be modified, the output wavelength is calculated in meters. Commercial Electric 25 ft. 3pF) in the tuner to 111. f 2 = Upper operational frequency in GHz. e. 2. This applies to generalized S. 295+j32. 5 x center F chosen. 49 m. Maximum Operating Voltage (Vrms) 4000. 13-1. Email. 854187817620. The formula is this: -. Cut-off Frequency (fc) GHz. 66 and 0. coax cross section. the cable is Tensolite (Carlisle) brand (came all the way from USA, not China) came already with BMA connectors soldered on both end. 6 . Operating above the cut-off frequency that results in interference in signal propagation. The trick is that I'm trying to use 75Ω RG6 coax for the matching section (because it is relatively inexpensive and low-loss), but I want a 50Ω impedance at the feed point. Distributed Inductance (L') For a coaxial cable, the inductance per unit length L' in henries per meter (H/m) is defined as. 95 metersA microstrip width calculator can calculate the width of a microstrip. 405 inches and has a maximum working voltage of up to 5000 Vrms. Early in my explorations of electricity, I came across a length of coaxial cable with a label of “50 ohms” printed along its outer sheath (Figure below). High return loss means low reflected power, so high return loss is good for a system. a suitable coaxial cable and, instead, insert a suitable thinner inner con-ductor leading to a higher characteristic impedance. First one is how to calculate the impedance of an equilateral patch antenna and. Print - Advertisement - This calculator. Simply put, the coax is losing 8. Figure [Math Processing Error] 7. Coaxial cable specifications often include the velocity factor, which is typically between 60% and 90% (1). diameter Schedule 40 PVC form. 81, giving an impedance of 120. A commonly-encountered form of parallel wire transmission line is 300 Ω 300 Ω twin-lead. If, on the other hand, a < δs or merely ∼ δs, then current density is significant throughout the wire, including along the axis of the wire. Feedpoint impedance and coaxial matching section. Choose from 50 Ohm, 75 Ohm, 93 Ohm and 95 Ohm coaxial cables or 78 Ohm and 100 Ohm Twinax cables. Insulation service. 2 OUTPUTS: Impedance = 51. ε = dielectric constant = ε0 * εr. Lcoax ≈ μ0μrL 2π ln( D d) L c o a x ≈ μ 0 μ r L 2 π l n ( D d) Where: Lcoax L c o a x = inductance of the coaxial cable in henries (H) μ0 μ 0 = permeability of free space = 4π×10 −7. High return loss means low reflected power, so high return loss is good for a system. However, the nominal refer-ence impedance of the analyzer is 50 + j0 Ω, rather than the complex characteristic impedance of the cable. From then on the dips occur when the cable is an odd number of quarterwaves, or the distance between each dip is caused by an additional half-wave. 20. 035 in), outer conductor diameter 3. 5 mm Coaxial Connector is a widely used standardized coaxial connector type with some interesting features. This online reflection coefficient calculator calculates the reflection coefficient (Γ) by entering the value of the characteristic impedance Z o (in ohms. In fact, striplines often make components such as band-pass filter's more accurately, with more symmetric roll-off and no lower cutoff frequency. A typical coax cable has 50 ohm characteristic impedance above about 1 MHz but that doesn't mean that's the impedance that the source sees because, if the load isn't 50 ohm then the "seen" impedance isn't 50 ohms and reflections will be present. Layout of the three coils. The following formula is used to calculate the cut-off frequency, lower & higher operational frequency of the rectangular waveguide. For coaxial cables the characteristic impedance will be typically between 20 and 150 ohms. In some cases, users require a custom impedance value. Why these values? One explanation is that the value of 50 ohms was selected because a coaxial cable with polyethylene dielectric with relative permittivity ε r = 2. Coax velocity factor of popular coax cable types is published in many places. Plugging this into the equation we calculate the cable length. This topic describes a technique for calculating the impedance of a waveguide. Because. The analytic calculation of the characteristic impedance of a transmission line from geometry is not always possible except for a few regular geometries (matching orthogonal coordinate systems). Twisted-Pair Impedance Calculator; Embedded Microstrip Impedance Calculator; Microstrip Impedance Calculator;A twisted-pair cable is simply two wires that are twisted together so as to reduce radiated EMI (electromagnetic interference) and mitigate the effects of received EMI. Zs = Ze + (R1 + R2) Z s = Z e + (R1 + R2) Where Zs is the line-earth loop impedance. This calculator is designed to calculate the characteristic impedance of a microstrip - a flat conductor suspended over a ground plane with a dielectric between them (see diagram below). Return loss (RL) is the ratio of the reflected power to the incident power, in decibels (dB). Click on any RF calculator below to get started. Use the frequency and layer thickness/Dk value to determine the antenna size. com If it. Although widely applied to. 0815 λ (wavelength, lambda or Wave) The physical length L is 0. Featured Magazine. × 10 −12 F/m is the. I used 100m for l. Pasternack's RF calculators and conversions section provides engineers valuable and easy-to-use tools ranging from complex mathematical formulas to simple conversions. If it's safe to assume that both drivers have an output of the same amplitude, we can even calculate the loss introduced by the cable: 20×log(1. In a nut shell the characteristic impedance of a coax cable is the square root of (the per unit length inductance divide by the per unit length capacitance). An air-spaced cable would shift signals at the speed of light c. Quarter Wave Transformer Impedance Calculator. 2. Cable Capacitance (pF/ft) 20. A directional coupler is a passive 4-port device used to sample a small amount of microwave power for measurement purposes. Below the cutoff frequency, power flow will be reduced. The impedance of a coaxial cable is a critical parameter that characterizes its electrical properties. If we look again at the example of the coaxial cable and leave it open at the end, achieving a characteristic impedance of ~377 Ω does not relate to anything about the fields. 5 dB. The inductance of a coax cable can be useful. All signals that travel on a transmission line are waves, whether they are harmonic analog. 05+j51. 86 mm] x 0. The following equation is used to calculate the ZS (Earth Loop Impedance). The flexible types (9913F and LMR-400UF) are preferred, particularly for rotatable antennas. μr μ r = relative permeability. The impedance of a coaxial cable is determined by its physical. Quarter Wave Transformer Impedance Calculator. The following calculator computes the resistance, inductance, inductive reactance, capacitance, charging current, and surge impedance for medium voltage shielded power cables. a = outside radius of inner conductor (inches) b = inside radius of outer conductor (inches) c = speed of light in a vacuum = 299,792 km/s = 186,282 mi/s. A coaxial cable of a specific impedance is determined by the ratio of the dimensions, not the absolute values. Cutoff wavelength and frequency. If you are interested in how to build a copper J-pole antenna, follow these instructions: Choose 145 MHz from the 2-meter frequency band, note the speed of light c, and calculate the wavelength λ from the formula λ = c/f = (299,792,458 m/s) / (145,000,000 1/s) = 2. 96. This arrangement minimizes coupling between the coils. × 10 −12 F/m is the. VSWR is defined as the ratio of the maximum to minimum voltage on a loss-less transmission line (expressed as 3. The impedance of the coax is a relationship of the capacitance per unit length and the inductance per unit length. The coax cable is RG-8X. The twisted pair helps create a more uniform inductance and capacitance per unit length of wire to ensure a constant impedance, by keeping the return path as close to the signal as possible. Perhaps the most common type of transmission line is the coax. 336 by 360, = 0. Schelkunoff in 1934, is a very convenient parameter for the prediction and control of EMI coupling through cable shields. The characteristic impedance of an infinite transmission line at a given angular frequency is the ratio of the voltage and current of a pure sinusoidal wave of the same frequency travelling along the line. My thoughts: The source sees from DC to approximately 300 kHz 117 Ohm Real Component (as 2x50 Ohm + 10*1. The formula defining characteristic impedance may be written as follows : Theoretical formula in the case of a perfect line. 150 MHz start by calculating the freespace wavelength… Wavelength(Freespace-7. Although this sounds somewhat crude and primitive, I have watched technicians perform such an “operation” several times with very good success. 150 MHz = 41. on the calculator devide 29. A quarter wave transformer is used to match two transmission lines with different impedances. where. Along the slot line, the electromagnetic wave encounters the substrate and the air, which serve as its transmission medium. More consistent results will usually be obtained by using a dedicated cable joiner or a plug and socket with the same impedance as the cable. Set Parameters as Desired. VSWR Conversion Table. UsefulFormulas. 35dB. Unlike cable used for mains or other power transfer, the impedance of a coaxial cable is not affected by its length. 125 MHz. You can perform the calculations, but by changing the outer diameter in Figure 3 by just two millimeters, you will find that the coaxial cable’s impedance changes from 75 ohms to 46 ohms. Looking at the datapoints and moving back from the antenna (75.