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About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024


    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while typing up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:


everythingRF RF & Microwave Parts Database (h1) - RF Cafe

Engineering Calculators & Converter Applets & Spreadsheets

Engineering Calculators & Converter Applet & Spreadsheet Websites - RF CafeThese calculators are offered free of charge - some by vendors and others by individuals. Some are stand-alone and others function online via Java from the web page. The majority are engineering calculators, but some are scientific calculators, some are amateur radio calculators, and some are electrician type calculators.

See also the RF Cafe Online Calculators and vintage Cardboard Slide Rule Calculators.

A good way to find on this page what you need is do a browser page search.

If you cannot find what you are looking for here, try the Software page.


Unit Conversion Tool - powerful, intuitive, and easy-to-use utility for quick and accurate conversion between almost every possible unit of measure, from one system to another. The latest version includes more than 2200 units in 78 categories. The categories include: length, area, speed, mass, numbers, volume, time, density, force, pressure, energy, power, flow, temperature, angle, light, fractions, data transfer, and many more. Fully functional Online version now available.

All About Circuits

This is a nice assortment (83 at this time) of electrical & electronics parameter calculators, with a couple mechanical types as well. There are many types of substrate impedance and line dimension calculators, and calculators for voltage dividers, inductance and capacitance, coax lines and waveguides, amplifiers, impedance matching, free space loss, EIRP, radar range, and noise figure.

AlphiMAX P2P Signal Propagation Calculator

A very nice graphical interface tools that enables you to compare manufacturers, while taking into account the terrain of your area, terrain type, climate, antenna type, define fade margin and more. Use of a GPS database produces a very accurate elevation profile between antenna locations.

Analog Devices Calculators

Big list of online calculators

Antenna System Evaluator

Evaluate consequences of SWR & feedline losses, KD6DKS.

ATC Tech-Select

Capacitor Calculation, American Technical Ceramics.

Attenuator Calculators

"T" and Pi topologies using online interactive Excel OWA technology.

Attenuator Calculator

Four topologies: "T", Pi, Bridged-T, Reflection.

Attenuator Calculator


Here is a JavaScript version for Pi and T attenuators - auf Deutsch.


Minimum loss attenuator design.

Besser Associates

415-949-3300 / Los Altos, CA

Broadcast Engineering Related Calculators

Allen's Broadcast Engineering Extravaganza

Lots of good JavaScript calculators: AM Common Point / Antenna Current Calculator, FM Transmitter Power Output Calculator, RPU/STL Transmitter Frequency Tolerance Calculator, AM Transmitter Harmonics Calculator, Free Space Loss Between Isotropic Radiators Calculator, 0.6 First Fresnel Radius Zone Calculator, VSWR Calculator, Coaxial Cable Loss Calculator, Coax Cable Loss/Antenna Gain Calculator, Opamp Gain Calculator

Cable Performance Calculators

Calculate loss & power, VSWR & return loss, by Times Microwave.


By webMathematica, scores of online interactive calculators for algebra, trigonometry, calculus, matricies, linear equations.

Calculator Edge

This has to be one of the Web's largest collection of unique (as opposed to copied) online calculators. Each of these topics has many calculators within them. General, Civil Engineering, Optical Engineering, Mechanical Engineering, Plastics Engineering, Metallurgy, Electronics Engineering, Electrical Engineering, Chemical Engineering, Physics, Ceramics, Oil & Gas, Structural Engineering.


Capacitor calculation, by Dielectric Laboratories.

Chemandy Electronics

+62 31 8914627 / Jawa Timur, Indonesia

Large selection of online interactive calculators for RF design, including attenuators, capacitance, resonance, RF traps, and microstrip impedance. Design, development and small scale manufacture of simple RF and Audio items. We also have the capability for ATE programming in Labview, HP/Agilent Vee or Visual Basic, and can produce associated test jigs.

Chemistry Calculators

Boyle's Law, Charles' Law, STP, molar volume, etc, by 1728 Software Systems.

Choke Designer

Inductor values using standard cores.

Coordinate System Converter

Convert between rectangular, polar, spherical, and cylindrical coordinates.

Connect802 Antenna System Designer

An on-line calculator that creates a wireless network antenna system design report based on various parameters that you provide. It will help you predict end-to-end performance and evaluate your network design when you plan a point-to-point, or point-to-multipoint outdoor wireless network deployment. You'll be able to analyze the radio link and tune network parameters for optimal link suitability.


Huge collection of converters and calculators.

Daycounter, Inc. Engineering Services

Calculators for switching power supply, air core inductors, Sallen-Key LP Butterworth filter, L matching network, standard resistor value, PI & T pad attenuator, reactance, series - parallel impedance conversion, Z-S-Y parameter conversion, Rollet Stability (K) Factor, complete RF amplifier design & analysis, LC resonance.

Dielectric Constant of Water (Complex)

Calculates the real and imaginary parts of the dielectric constant for water, sung temperature, salinity, and frequency. By Gareth Harris

Dirac Delta

"Science and engineering encyclopedia." Hundreds of JavaScript calculators, definitions, historical information, etc.


Advanced features including support for complex numbers, unit conversion, base conversion, and has a built in equation solver. eCalc is one of the best calculators on the web and runs completely in your browser without requiring any special plugins. Electrical engineers will find eCalc's complex math especially useful since it supports both rectangular and polar formats. eCalc supports both RPN and Algebraic Input Modes.


Java applets for engineering education.

Engineering Calculators on Educypedia

A pretty good collection of links to online calculators - satellites, attenuators, Smith Chart, VSWR, free space loss, etc.

EIA Equipment Rack Stencils for Visio

By Kirt Blattenberger.

EIA Tube Bases for Visio

Electromagnetic Field Applets

Very nice graphical output and user interface, with animation.

- Wave Propagation

- Field Polarization

- Oblique Incidence

- Oblique Incidence on Lossy Medium

- Parallel Plate Waveguide

- Rectangular Waveguide

- Dielectric Slab Waveguide

everything RF

A nice collection of RF calculators.

- Attenuator Calculator

- Microstrip Impedance Calculator

- Coax Impedance Calculator

- Cascaded Noise Figure Calculator

- Skin Depth Calculator

- Wavelength Calculator

- dBm to Watt Calculator

- Watt to dBm Calculator

Excalibur RPN Calculator Applet

Excalibur does not use more conventional "algebraic" notation like many low-end calculators on the market. Instead it uses the high-powered parenthesis-free RPN notation (Reverse Polish Notation).

Fast Fourier Transform Calculator

Do an FFT by entering the time domain data in the Time Domain Data box with each sample on a new line. For complex (I and Q) data, the real and imaginary components should be on the same line separated by a comma. Do an Inverse FFT by entering the frequency domain data in the Frequency Domain Data box with each sample on a new line. For complex (I and Q) data, the real and imaginary components should be on the same line separated by a comma.

Field Strength Calculator

Enter frequency and antenna gain, then any one of received power, electric field strength, magnetic field strength, or power density and this calculates the others.

Filter Coupling Matrix Calculator

Facilitates synthesis of N+2 coupling matrices for Chebyshev bandpass filtering functions, with arbitrary finite-position transmission zeroes.

Filter Design Spreadsheets

Waveguide Filter Designer

Combline and Interdigital Filter Design Spreadsheet

RF Shop

Financial & Mortgage Calculators

Over 100 personal finance calculators.

Financial Calculators

Loan amortization, interest, loan payment by 1728 Software Systems.

FM Antenna Calculator

by ERI (Electronics Research, Inc.)

Plots FCC 60 dBu contours right on the page. Also many PDF files with Engineering Tables: Geotechnical Investigations for Antenna Support Structures, Classes of FM Stations, FM Broadcast Channels, AM Tower Heights by Frequency, 54 dBu Contour Distances, 60 dBu Contour Distances, Site Plot Plan, Wind Speed Map, Ice Probability Map, Antenna Support Structure Design Radius of Curvature Requirement.

Free-Space Loss Calculator

Fresnel Clearance Zone


Distance between two points using Latitudes and Longitudes

Flex Analysis

Evaluate thermal/mechanical performance of flex circuits by Rogers Corporation.

Frequency Finder - Open TV Channel Applet

Sennheiser searches the FCC database for an open channel for running interference-free wireless systems.

Fresnel Clearance Zone Calculator

By TeraBeam

Fresnel Zone Calculator

The calculator will generate the radius of the first Fresnel zone only (at the obstacle point or the mid-point), the 60% (no obstacle) radius and the height of the earth curvature at the mid-point of the Total link distance. By Wireless Connections.


Scientific calculator with extended capabilities. Advantages include a simple input format even for the most complicated scientific formulas; i.e., enter "10pi" instead of "10*pi" or complex numbers as "1+2i".

HP48 Calculator Programs

Lots of engineering programs.


Huge collection of online calculators for tax, finance, math, engineering, mortgages, logistics, loans, budgets, conversions, sports & health, statistics, mechanics, and other topics.

Impedance Matching Network Designer

John Wetherell, Berkeley, CA.

Inflation Calculator

U.S., Canadian, and Italian versions. Enter begin and end dates and get equivalent dollar values,

by S. Morgan Friedman.

Inflation Calculator

U.S. Bureau of Labor Statistics (BLS).

J-Pole Antenna Calculator

Enter the operating frequency and calculate antenna dimensions - online.

Julian Date Calculator

Calculates JDs for a given month.

Link Budget Calculator

A tower-to-tower, over-the-air JavaScript calculator, by Wireless Connections.


Leslie Green / U.K. - A Windows program (Freeware) that calculates two-tone intermodulation products up to the 30th order.

Martindale's Calculator On-Line Center

More than 20,000 calculators - this site has grown incredibly over the years.


Multifunctional units converter.

Microwave Impedance Calculator (MWIJ 1.0)

Substrate line impedance calculator by Rogers Corporation. Written in Java - nice.

Mortgage Calculators

Large variety of financial calculators for mortgages, principal calculation, cost per thousand, affordability, income requirements, FHA, refinance, HELOC, loan comparison tools, points, rent vs buy, & more.

Mortgage Calculator

8 different calculators: Mortgage calculator, Affordability, Early Pay-Off, Interest Only, Advanced Mortgage calculator, Mortgage Refinance, Basic Amortization, and Comparison calculator

N Calculators

Electronic circuit design calculators can assist you to solve, analyze and determine the circuit design with capacitors, inductors, resistors, diodes, transistors, etc. Many other types of financial, mathematical, and science calculators.

Noise Figure  <-->  Noise Temperature Calculator

Online Conversion

Convert just about anything to just about anything else.

PCB Trace & Via Calculator

A very complete set of online calculators for microstrip, embedded, and differential microstrip impedance; stripline and differential stripline impedance; stripline and microstrip crosstalk; current-carrying capacity of traces and thermal vias; heat dissipation of thermal vias. By Sören Nilsson.

PLL Phase Noise Calculator

By Hittite Microwave (now Analog Devices).

Poles & Zeros Calculator

Move the poles and zeros to see the frequency domain response.

Power Calculator

Motor & line calculations, conversions.

Radio Calculators

Pi attenuators and air inductor java calculators by Jim Hawkins.

Random Science Tools and Calculators

The intention of this site is to produce scientific tools and calculators, and store information which will be useful to scientists, engineers, students and enthusiasts.





Resistor Color Code Calculator (Reversible)

This resistor color code calculator also provides a table of nearest standard values of resistors for standard tolerances.

Resistor Ratio Calculator

Leslie Green / U.K.

A resistive network calculator for problems using two or three fixed resistors. You have to use standard values, but you need some silly ratio like 3.245 V from a 10 V source. This program helps you to pick the optimum resistor values for simple resistor dividers or opamps (inverting and non-inverting). Freeware.

RF Cafe Calculator Workbook

Collection of commonly used calculators including Attenuators, Bandpass Filters, Cascaded Components, Coils / Inductors, Delta-Wye (Resistors), Directional Couplers, Doppler Shift, Highpass Filters, Lowpass Filters, Mixer Frequency Conversion, Near / Far Field, Noise Figure|Temp, Path Loss, 1-Way, Path Loss, 2-Way, Propagation Time, Radar Blind Speed, Radar Horizon / Line of Sight, Rectangular Cavity, Skin Depth, Smith Chart, VSWR|RL|Gamma, Voltage Divider, Voltages & Power - Vrms, Vavg, Vpk

RF Cafe Online Calculators

Many online calculators for noise figure/temperature, filter responses, voltage dividers, waveguide cutoff frequency, VSWR-return loss-reflection coefficient conversions and more, by Kirt Blattenberger.

RF Calc

General purpose engineering calculator by MilMega - includes table of physical constants, component parameter calculators (capacitance, inductance, resonance, pads), multiple transmission line calculators.

RF & Analog Tutorials w/Java Apps Website

This is a VERY nice collection of Java applets and some PDF format tutorials. Antenna patterns, waveguide modes, electromagnetic wave fronts, interactive Smith chart, transmission lines, standing waves, resonant circuits, radiation of wires, cross-talk, much more. By Amanogawa.

RF Cascade Workbook 2018

RF, system, cascade for Excel spreadsheet.

RF Workbench

RF, system, up/downconverter, spurious analysis, budget - best value out there.

RPN Calculator

Kelly Painter's RPN calculator - click for full-size imageThis handy Reverse Polish Notation calculator was written by the infamous Kelly Painter. Note the logo in the upper right corner (hover your cursor over it).

Satellite-Related Calculators

Sun interference, power-to-noise, tilt angle, antenna gain and more than thirty other calculators.

Satellite Link Budget Calculator

Uplink/downlink calculator, Satellite Signals site.

Signals & Noise

Java applet for exploring random processes.

Smith Chart for Visio

By Kirt Blattenberger.

Sunshine Design Engineering Services

Ramona, CA

Design specialties - hardware, CAD and software engineering. Test Engineering Services - 20 years experience RF/Microwave and Semiconductor Parametric Test. Electronic Calculator - Multiple pages of calculators for capacitance, resistance, inductance, attenuation, microstrip, resonance, etc. Many astronomical calculators.

SWR Calculator

VNA Help - for microwave network analyzers.

Transmission Line Calculator

The CircuitCalculator.com Website

Excel-based calculator

TRL / LRL Calculator

TRL (Through, Reflect, Line) and LRL (Line, Reflect, Line) reference plane calculators provided by Electro-Photonics.


Transmission Line Calculator by Applied Wave Research. This file seems to be no longer available on the AWR website.

Ultra Converter I

Ultra Converter II

If these to converters don't have it, you don't need to convert it! by 1728 Software.

Unit Converter

This is a very extensive measurement value and units converter for length, weight, height, area, temperature, time, pressure, speed, force, etc. Each and every converter has a detailed explanation with an example.

Vertex 42 - Engineering calculators & converter applets & spreadsheets.

Voltage Divider Resistor Calculator

Table of two-resistor voltage dividers using standard 5% tolerance resistor. Opamp feedback-input resistor pairs can also be specified. Very clever cell shading scheme for indicating deviation from exact ratio that is specified. Provided by Mark Rushakoff.

VSWR, Power Converter, Inductance Calculator

972-3-6175082 / Israel

Free downloadable VSWR, power converter, inductance calculator, written by Dr. Ronen Holtzman for Elisra Microwave Division engineers.

Waveguide Filter Dimension and Electrical Response Calculator

By Guided Wave Technology.

Waveguide Applets

Very nice graphical output and user interface, with animation.

Web Cool Tools

RF & microwave design applets that use numerical input or sliders for setting parameters.


Waveguide structure design tool.

Corrugated Low-Pass Filter Design Workshop

Waveguide & EM Calculators

This is a very nice Java/JavaScript-based set of calculators with a great user interface.

Wireline Calculator

WLAN Link Planning Calculators

Many calculators for wireless link planning: Fresnel zone, diffraction, path loss, link budget, cable loss.

Yagi Java Applet

Change frequency, element diameter, and number of segments.

Innovative Power Products Couplers
RF Superstore (RF Components) - RF Cafe
Innovative Power Products Passive RF Products - RF Cafe

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