Wireless InSite® Propagation Software
REMCOM 
Wireless InSite is a suite of ray-tracing models and high-fidelity EM solvers for the analysis of site-specific radio wave propagation and wireless communication systems. The RF propagation software provides efficient and accurate predictions of EM propagation and communication channel characteristics in complex urban, indoor, rural and mixed path environments.
License Required
CST Studio Suite
SIMULA, Dassault Systèmes
CST Studio Suite is an industry-leading EM simulation tool, with multiple solvers suitable for a wide range of applications. Engineers can use these solvers to simulate antenna radiation patterns and coupling, both in isolation and as installed in realistic environments. The Hybrid Solver Task, combining FIT and MLFMM methods and the Asymptotic Solver offer an efficient way to calculate 3D propagation around large structures such as buildings and aircraft.
WinProp
Altair HyperWorks
WinProp is one of the most complete suite of tools in the domain of wireless propagation and radio network planning. The highly accurate and very fast empirical and deterministic propagation models are available for a wide range of scenarios including rural, urban, indoor, tunnel, vehicular. WinProp, together with FEKO provide leading solutions for vehicle-to-vehicle and vehicle-to-infrastructure communications, which are important for autonomous driving (license required).
www.altairhyperworks.com/winprop
EIRP Calculator 
Pasternack
Pasternack's EIRP Calculator determines the radiated power given the transmitter power, the cable loss to the antenna and the gain of the antenna.
Free Online
Free-Space Path Loss Calculator
Pasternack 
Pasternack's Free Space Path Loss Calculator calculates the loss (in dB) between two antennas where the gain, distance and frequency are known.
Free Online
Free-Space Path Loss Calculator 
Proxim Wireless
Free Space Loss is the transmission loss between two antennas, separated by a distance. Enter the operating frequency in MHz (2400 for 2.4 GHz, 5800 for 5.8 GHz, etc.) and the distance between the two antennas in miles. The final value represents a first order approximation and should only be used as a guide.
Free Online
Friis Path Loss Calculator 
Pasternack
Pasternack's Friis Transmission Equation Calculator will calculate the received power from an antenna at some distance given a transmission frequency and antenna gains.
Free Online
Fresnel Clearance Zone Calculator 
Proxim Wireless
Unlike the popular view of a Line of Sight which a clear unobstructed clear straight line. Radio frequency line of sight is defined by Fresnel Zones which are ellipse shaped areas between any two radios. The primary Fresnel zone is required to be at least 60 percent clear of any obstruction to ensure the highest performance of wireless link. The radius of the Fresnel Zone at its widest point is calculated with the Fresnel Zone Calculator. The final value represents a first order approximation and should only be used as a guide. No guarantees or warranties are implied accordingly.
Free Online
Link Budget Calculator 
Pasternack
Pasternack's Link Budget Calculator determines the received signal strength (in dBm) given a systems amplifier gains, antenna gains and space loss.
Free Online
Maximum Field Strength Calculator
Daycounter, Inc.
This calculator calculates the maximum field strength that a dipole antenna could produce at 3M assuming 100 percent antenna efficiency. This provides an upper bound for transmitter power.
Free Online
P2P Signal Propagation Calculator 
AlphiMAX
Determine whether a wireless link will work given the specific locations you are trying to connect, prior to purchasing equipment or climbing a tower. The Point-To-Point Estimator is a free web based tool with 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.
Free (Registration Required)
Power Density Calculator
Pasternack
Pasternack's Power Density Calculator is designed to give the power density, in Watts per square meter, at a given distance, output power and antenna gain. Please note that this calculator is only valid for far-field calculations.
Free Online
Radar Maximum Range Calculator 
Pasternack
Pasternack's Radar Maximum Range Calculator produces an ideal maximum range of a radar antenna using the properties of the antenna.
Free
Frequency to Wavelength to Energy Calculator
BYU
To convert wavelength to frequency or energy, use this BYU calculator with formulas and unit noted.
GTD newFASANT
newFASANT Software
On board antennas 3D analysis and coverage parameters for radio communications systems. GTD is a very efficient computer tool for: the 3D analysis of antennas on board satellites, aircrafts and other complex bodies. The 3D analysis of coverage and channel parameters (impulse response, CDMA analysis, power delay profiles, etc.) in radio communications in urban, semi-urban environments and indoor communications. It can compute the levels of signal generate by one or several antennas placed inside or outside the building. The program's kernel is based on Geometrical Optics (GO), Physical Optics (PO) and Uniform Theory of Diffraction. A combination of the Angular Z-Buffer (AZB), the Volumetric Space Partitioning (SVP) and the A* heuristic algorithm is applied for the ray-racing acceleration. Also, provides functionalities to dynamic and parametric simulations. GTD can import geometries from many CAD tools such as: AutoCAD, Rhino, etc.