The W8IO Antenna Site

VHF-UHF Long Boom, Very High Performance Antenna Designs

(links updated 27 Sep 2016)

From this data and these NEC files, you can compare the performance between the various models without manufacturer hype. You could also build your own long beam if you have the right tools/test equipment and the knowledge of how to make the boom corrections. Back in the 1970's and 1980's, US hams had the advantage in designing and building state of the art, high performance antennas for VHF/UHF. Today, the Europeans seem to have taken the lead. I would like to encourage more experimentation and home building by North American VHF/UHFers!  It's also less expensive.  Check out the price of the popular LFA Yagis from England!

For contest and normal terrestrial operations, I would choose the antenna with the most forward gain for a given boom length. The sidelobes and backlobes are only important if you have noise generators or other stations that you need to eliminate in those directions. For EME use, I would choose the antenna with the highest G/T or the best F/R and lowest sidelobes for a given boom length. VE7BQH's G/T values are given for 4 bay arrays with specific boom spacing.  Please refer to his note for complete details. VK3DIP's YagiCAD will calculate a similar G/T for a single Yagi system. Most of the long boom antennas shown below are what I consider to be Very High Performance Yagis. I have separated out those antennas which I have called Ultra High Performance Yagis.  These UHP Yagis will have F/R greater than 30 dB in both planes and first sidelobes at -20 dB or better from the main lobe. Also, these UHP Yagis will have gain at or above the DL6WU gain curve.

• VE7BQH Gain table for 50 MHz (DXMaps)
• VE7BQH Gain table for 144 MHz (DXMaps)
• VE7BQH Gain table for 432 MHz (DXMaps)
• 6m_moxon (NEC file) a 6.2 dBi "Moxon rectangle" for 50.1 MHz
• 6m_3el_yagi  (NEC file) an 8.1 dBi low backlobe Yagi for 50.1 on a 6' boom
• 6m_4el_yagi  (4NEC2 file) a 9.8 dBi Yagi for 50.1 on a 12' 6" boom
• VHF/UHF Long Yagi Workshop
• GAL-ANA (MMANA-GAL)
• EZNEC
• AC6LA's AutoEZ program - automated use of EZNEC
• YagiCAD Design Software
• Antenna Design Software: 4NEC2
• NEC/MP a multicore engine for 4NEC2 - contact Roger for more info
• YT1NT TANT (Antenna Noise Temperature) Software - DG7YBN
• TANT Manual (DXMaps)
• How to use 4NEC2 with TANT - WB0DGF
• Yagi - Specific Design Software and file i/o comparison

50 MHz long boom Yagi NEC files (23-36 foot booms)

The antennas shown in red are experimental and have not yet been built or tested. F/R includes all backlobes.

144 MHz long boom Yagi NEC files (22-37 foot booms)

The antennas shown in red are experimental and have not yet been built or tested. The antennas shown with * have complete instructions for building. F/R includes all backlobes. Models ending in "V" have a "V" shaped driven element. Models ending in "U" have a "U" shaped reflector.  Models ending in "FD" have a horizontal folded dipole as the driven element.

# These G/T values are calculated based on stacking distances of  4.0m (E-plane) and 3.8m (H-plane).

## These G/T values are calculated based on stacking distances of  4.2m (E-plane) and 4.0m (H-plane).

* These G/T values are calculated based on stacking distances of  4.4m (E-plane) and 4.2m (H-plane).

** These G/T values are calculated based on stacking distances of  4.6m (E-plane) and 4.4m (H-plane).

*** These G/T values are calculated based on stacking distances of  4.8m (E-plane) and 4.6m (H-plane).

Cushcraft, Hy-Gain and M2 antennas can be purchased through many US dealers.  The K1FO antennas can be purchased through Directive Systems.  The G0KSC LFA Yagis can be purchased through Innovantennas-US or through Force-12 (these are shipped from England).  DK7ZB antennas may be purchased through VPA Systems.

222 MHz long boom Yagi NEC files (17-33 foot booms)

The antennas shown in red are experimental and have not yet been built or tested. F/R includes all backlobes. For the YagiCad G/T, Tsky=70 and Tearth = 600.

Cushcraft and M2 antennas can be purchased through many US dealers.  The K1FO antennas can be purchased through Directive Systems.

432 MHz long boom Yagi NEC files (17-30 foot booms)

902 MHz long boom Yagi NEC files (6-20 foot booms)

These antennas have been built, tested and are currently in use.

1296 MHz long boom Yagi NEC files (10-20 foot booms)

These antennas have been built, tested and are currently in use.

The performance numbers listed in the tables above are from my NEC2 and NEC4 simulations except for the G/T values, which come from VE7BQH's tables. These numbers will vary slightly due to factors such as element segmentation density and losses due to aluminum conductivity.

Element Length Correction due to Boom

The VHF/UHF antenna NEC files 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 15% the diameter of the boom. For example, for a 36" (raw length) insulated element passed through the center of a 1" metal boom, the YU7EF correction factor is 0.15", so the actual length should be 36.15" when built.  The table below gives correction factors for common US boom diameters.

Various antenna experimentors have similar correction factors, as shown below.

Here is a link to YU7EF's Boom Correction Notes.

Here is a link to YU1AW's Boom Correction article.

Here is information from the VHF/UHF Long Yagi Workshop.

Here is a link to DG7YBN's Boom Correction Notes and his Practical Yagi Building page.

Here is a link to SM5BSZ's collection of Boom Correction information.

Here are some ideas and hints to help with your home antenna construction.

Comments and corrections/additions are welcome!

contact Roger: email to 

rgcox2 (at) gmail.com

Roger Cox W8IO - Spring Lake, MI