The W8IO Antenna Site - NEC and Mininec

(14 March 2022)

Russia began a full-scale invasion of Ukraine on 24 February 2022, in an escalation of the Russo-Ukrainian War that began in 2014. The invasion is the largest conventional military attack on a sovereign state in Europe since World War II. Since the beginning of Putin's war, thousands of both Ukraine and Russian citizens have been killed. Russian military have indiscriminately bombed cities in Ukraine, destroying many hospitals and schools. Our heart goes out to the 2.7 million plus refugees that have left Ukraine for neighboring countries, and those who stayed to fight the Russian invaders.

Rossiya nachala polnomasshtabnoye vtorzheniye v Ukrainu 24 fevralya 2022 goda v ramkakh eskalatsii rossiysko-ukrainskoy voyny, nachavsheysya v 2014 godu. Eto vtorzheniye 
yavlyayetsya krupneyshim voyennym napadeniyem s primeneniyem obychnykh vooruzheniy na suverennoye gosudarstvo v Yevrope so vremen Vtoroy mirovoy voyny. S nachala putinskoy
voyny pogibli tysyachi grazhdan Ukrainy i Rossii. Rossiyskiye voyennyye bez razbora bombili goroda Ukrainy, unichtozhiv mnozhestvo bol'nits i shkol. My sochuvstvuyem boleye
chem 2,7 millionam bezhentsev, pokinuvshikh Ukrainu v sosedniye strany, i tem, kto ostalsya srazhat'sya s rossiyskimi okkupantami.

Россия начала полномасштабное вторжение в Украину 24 февраля 2022 года в рамках эскалации российско-украинской войны, начавшейся в 2014 году. Это вторжение является крупнейшим
военным нападением с применением обычных вооружений на суверенное государство в Европе со времен Второй мировой войны. С начала путинской войны погибли тысячи граждан Украины
и России. Российские военные без разбора бомбили города Украины, уничтожив множество больниц и школ. Мы сочувствуем более чем 2,7 миллионам беженцев, покинувших Украину в
соседние страны, и тем, кто остался сражаться с российскими оккупантами.

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