w8io

The W8IO Antenna Site - IO-144-14V Yagi

(updated 28 Sep 2016)

This particular antenna design was inspired by Hartmut DG7YBN and he was inspired by Günter DL6WU and Brian K6STI. His designs blend extremely high antenna gain, high G/T (which means a low noise temperature) along with a broad gain and VSWR bandwidth. The DE design is also very easy to build and allows adjustment of VSWR without significantly affecting the gain and pattern performance. A broad VSWR and gain bandwidth is ideally suited for wet and snow/ice climates where accumulation of moisture on the elements can lower the antennas resonant frequency and degrade performance. In this design, I have adjusted the spacing and element lengths slightly to increase the Front/Rear to values over 30 dB in each plane. The E-plane achieves an amazing 34.52 dB Front/Rear (all lobes from -90 to -180 degrees) at 144.1 MHz. This allows the antenna to reject terrestrial noise sources to an extremely high degree for improved EME performance in noisy locations. Element diameters are common US sizes (1/4" and DE 3/8").

IO-144-14V Performance

Electrical Performance:                     0.250" Element Diameter            
Directive Gain (dBi)                                        16.28                                               
Power Gain (dBi)                                            16.18                                               
E-Plane F/R (dB)                                            34.52                                               
H-Plane F/R (dB)                                            30.15                                              
E-Plane 1st Sidelobe (dB)                              -21.2                                                 
H-Plane 1st Sidelobe (dB)                             -17.7                                                 
E-Plane Beamwidth (deg)                                30.2                                                 
H-Plane Beamwidth (deg)                                32.2                                                
Max VSWR (144-146 MHz)                           1.5                                                  
4 Bay G/T (dB) at 4.4m (E) x 4.2m (H)          -1.18                                                

Mechanical Performance:
Boom Length        27.2 feet        8.29 m        4.0 wavelength

Boom Construction:
Recommended Boom diameters: 1" to 1.5" either square or round (DX Engineering or On-Line Metals)
I recommend either 6061-T6 tubing or 6063-T832 tubing for strength. 6061-T6 is more expensive.
DX Engineering 6063-T832 round tubing:
     0.875" OD x 0.058" wall x 6 feet = $6.00
     1.000" OD x 0.058" wall x 6 feet = $6.30
     1.125" OD x 0.058" wall x 6 feet = $7.00
     1.250" OD x 0.058" wall x 6 feet = $8.00
     1.375" OD x 0.058" wall x 6 feet = $8.70
     1.500" OD x 0.058" wall x 6 feet = $9.50
Tubes with 0.058" walls can telescope together and can be used as wall doublers to strengthen and adapt to smaller diameters.
Heavy duty (90 mph) boom construction uses 1.5" OD sections at center tapering down to 1" OD sections at ends.
Moderate duty (75 mph) boom construction uses 1.25" OD sections at center tapering down to 1" or 0.875" OD sections at ends.
How to drill holes in round aluminum tubing:
     Drilling of Round Hole in Round Pipe
     Drilling Holes in Pipe
     Drilling Round Stock
     Poor Mans DRO



Parasitic Element Construction:
Recommended element insulators: Directive Systems $18 for bag of 50 (1/4")
Recommended element keepers: Directive Systems $17 for bag of 50 (1/4")
Recommended element sources: On-Line Metals, McMaster-Carr
I recommend Online Metals - Extruded 6061-T6511 1/4" Rod - $1.76 for 6 feet (72 inches)


Boom to Mast Clamp:
     1.5" U-Bolt clamps for the boom
     2.0" U-Bolt clamps for the mast
       DX Engineering Boom to Mast Plate


Driven Element Construction Hints:
     DG7YBN hints
     Hy-Gain VHF DE insulator with elements on bottom side

Model Files:
144-14V NEC file  EZNEC file (1/4" elements)


IO-144-14V US Dimensions
Element Cum Spacing
(m / in)		 0.250" Element Dia
Ele Half-Lengths (m)
for NEC simulation		 Element Lengths
Full Lengths (in)
dielectric boom
(+0.0)		Full Element
Lengths (in)
insulated thru
0.875" metal boom*
(+0.125)		Full Element
Lengths (in)
insulated thru
1.0" metal boom*
(+0.150)		Full Element
Lengths (in)
insulated thru
1.125" metal boom*
(+0.188)		Full Element
Lengths (in)
insulated thru
1.250" metal boom*
(+0.215)		Full Element
Lengths (in)
insulated thru
1.375" metal boom*
(+0.255)
Reflector 0 0.5095 40.118
40.24340.26840.30640.33340.373
Driven Element
(0.375" OD)		 0.286 / 11.260 0.4905 38.622
-----
D1 0.421 / 16.575 0.482 37.953
38.07838.10338.14138.16838.208
D2 0.707 / 27.835 0.4775 37.598
37.72337.74837.78637.81337.853
D3 1.246 / 49.055 0.466 36.693
36.81836.84336.88136.90836.948
D4 1.886 / 74.252 0.4585 36.102
36.22736.25236.29036.31736.357
D5 2.628 / 103.464 0.451 35.512
35.63735.66235.70035.72735.767
D6 3.419 / 134.606 0.445 35.039
35.16435.18935.22735.25435.294
D7 4.239 / 166.889 0.439 34.567
34.69234.71734.75534.78234.822
D8 5.086 / 200.236 0.4345 34.213
34.33834.36334.40134.42834.468
D9 5.939 / 233.818 0.4315 33.976
34.10134.12634.16434.19134.231
D10 6.771 / 266.574 0.431 33.937
34.06234.08734.12534.15234.192
D11 7.580 / 298.425 0.4295 33.819
33.94433.96934.00734.03434.074
D12 8.290 / 326.377 0.4195 33.031
33.15633.18133.21933.24633.286

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

Driven Element details (in):
DE


4NEC2 Patterns:
az

el

Comments are welcome!

contact Roger: email to 

rgcox2 (at) gmail.com

Roger Cox - Spring Lake, MI