The W8IO Antenna Site - NEC and Mininec

(21 October 2016)

NEC Software for Yagi Design

Software / Version / Author Type of Yagi Design Input/Open/Import File Formats Save/Export File Formats Price
version 5.8.16
Arie Voors
- .nec
.ez (EZNEC)
.ant (AO)
version 5
Roy Lewallen W7EL
- .ez (EZNEC)
.ez EZNEC v. 5 ($89)
EZNEC+ v.5 ($139)
EZNEC Pro/2 v.5 ($500)
Demo 2.0.10
Dan Maguire AC6LA
- .weq (AutoEZ)
.ez (EZNEC)
.ant (AO)
.maa (MMANA-GAL)
.weq (AutoEZ)
.ez (EZNEC)
Demo - Free
full version - $79
Paul McMahon VK3DIP
includes sample Yagi files .yc6 (YagiCAD)
.yag (YagiCAD)
.nec (4NEC2)
.yw (Yagi for Windows)
.ant (AO and MN)
.yag (YO)
.yc6 (YagiCAD)
.nec (4NEC2)
YW - Yagi for Windows
Dean Straw N6BV
- .yw (Yagi for Windows)
.yag (YO)
.yw (Yagi for Windows) included in ARRL Antenna Handbook
Yagi Calculator
John Drew VK5DJ
DL6WU long boom
Yagi creation
no file import .yag (YO)
.maa (MMANA-GAL)
Kok Chen W7AY
- .nec ? Free
(Mac OS-X version of NEC)
- ? ? ?
- .nec .nec $39.95
Roger Cox W8IO
DL6WU long boom
Yagi creation
.yio (YAGio),yio (YAGio)
.nec (4NEC2)
.yag (YO)
.mma (MMANA-GAL)
.yc6 (YagiCAD)

Note: K6STI's AO and YO software no longer available. His older versions will not work in Windows 7 and 8.

NEC/MININEC-based Software Vendors:

Other MOM-based Software Providers:

FEA-based Software Vendors:

Antenna Structural Analysis Software:

NEC/MININEC Organizations and Resources:

Other RF and Antenna Software

(links updated 18 Feb 2013)

Learn How Antennas Work!

Linear Dipole - set length to 0.5 (half-wavelength dipole) and notice that the impedance is near 73 ohms.  Radiation pattern shown is typical figure-8 pattern. When a half-wave dipole is close to ground, the impedance is lowered to near 50 ohms.  Thus a perfect match to 50 ohm cable.

-set length to 1.27 wavelength.  This is called an Extended Double Zepp antenna and produces the maximum gain possible from a simple center-fed dipole.  Notice that the radiation resistance (impedance) is about 90 ohms.  This antenna can be matched to 50 ohms by using a series inductor. Half of this antenna is 5/8 wave and is a common length for 2m mobile antennas. The 5/8 wave antenna is typically fed against a ground plane (car roof) and is usually matched with a tapped inductor.

-set length of dipole to multiples of 1/4 wave on each side (e.g. 0.5, 1.5, 2.5, etc.).  Notice how these lengths produce an radiation resistance (impedance) close to 100 ohms.  The patterns of these are made up of many lobes (cloverleaf pattern).

How do antennas produce gain?

updated 17 Jan 2006

Lincoln Amateur Radio Club Antenna Class

Links to Software and other information

updated 10-21-16

LPCAD - Log Periodic CAD

Now available for Windows 7 and 8!

LPCAD version 3.4 is now available!  LPCAD 3.4 runs fine under Windows 2000, XP, Vista and Windows 7.  Please email me at rgcox2 (at) gmail.com for details.

updated 17 July 2015

NEC Model Library

The following files and links point to NEC/AO/YO models of various Ham antennas that I have simulated and/or tested over the past 30 years as an antenna designer. The NEC files may be used with any of the NEC-2 or NEC-4 programs such as 4NEC2, GNEC or cocoaNEC, however some of them with tapered elements may only be simulated accurately by NEC-4 or other MININEC-based software. These models will indicate in the CM lines if they need to use NEC-4 or 4NEC2. These models have varying degrees of accuracy. Some may be very close to actual performance. Others may only be an estimate. They are for you, as the experimenter, to use and improve.  This list will grow as I check each file before uploading, so check back often. Have fun!


VHF NEC Models:

The VHF antennas shown above include the "raw" element lengths.  That is, the element lengths are those used with a wood or plastic (dielectric) boom or supported above or below a metal boom with an large insulator. To convert these raw lengths into actual lengths used when passed through the center of metal booms, you need to add a correction factor, based on whether the element is insulated and passes through the center of a metal boom, or is shorted directly to the metal boom with a clamp.

If the element is insulated when it passes through the metal boom, the correction factor is approximately 1/4 the diameter of the boom.  For example, for a 36" (raw length) insulated element passed through the center of a 1" metal boom, the correction factor is 0.25", so the actual length should be 36.25" when built.

(updated 16 July 2013)

Comments are welcome!

contact Roger: email to 

rgcox2 (at) gmail.com

Roger Cox - Spring Lake, MI