W8IO Antenna Site

The W8IO Antenna Site - 144-18V2 Yagi

(updated 3 Oct 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 34.08 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 3/16").

IO-144-18V2 Performance

Electrical Performance:                    0.250" Element Diameter            0.188" Element Diameter
Directive Gain (dBi)                                        17.42                                            xx
Power Gain (dBi)                                            17.31                                            xx
E-Plane F/R (dB)                                            34.08                                            xx
H-Plane F/R (dB)                                           30.07                                            xx
E-Plane 1st Sidelobe (dB)                            -17.9                                        xx
H-Plane 1st Sidelobe (dB)                             -15.5                                              xx
E-Plane Beamwidth (deg)                               26.5                                            xx
H-Plane Beamwidth (deg)                                28.0                                            xx
Max VSWR (144-146 MHz)                           1.5                                                xx
4 Bay G/T (dB) at 4.4m (E) x 4.2m (H) -0.xx                                           xx
4 Bay G/T (dB) at 4.4m (E) x 4.4m (H) -0.xx                                           xx
4 Bay G/T (dB) at 4.6m (E) x 4.4m (H) -0.xx                                           xx
4 Bay G/T (dB) at 4.8m (E) x 4.6m (H) -0.07                                           xx
4 Bay G/T (dB) at 4.8m (E) x 4.8m (H) -0.xx                                           xx

Mechanical Performance:
Boom Length        37 feet        11.3 m        5.43 wavelength
Recommended Boom diameters: 1" to 1.625" either square or round (Texas Towers, DX Engineering or On-Line Metals)
Recommended element insulators: Directive Systems
Recommended element sources: On-Line Metals, McMaster-Carr

144-18V NEC file EZNEC file (1/4" elements)

IO-144-18V2 Dimensions

Element	Cum Spacing (m)	0.250" Element Diameter Element Half-Lengths (m) Dielectric Boom or NEC simulation	0.188" Element Diameter Element Half-Lengths (m) Dielectric Boom or NEC simulation
Reflector	0	0.5095	xx
Driven Element (0.375" OD)	0.286	0.4905	xx
D1	0.421	0.482	xx
D2	0.707	0.4775	xx
D3	1.246	0.466	xx
D4	1.886	0.4585	xx
D5	2.628	0.451	xx
D6	3.419	0.445	xx
D7	4.239	0.439	xx
D8	5.086	0.4345	xx
D9	5.939	0.4315	xx
D10	6.771	0.431	xx
D11	7.592	0.432	xx
D12	8.393	0.434	xx
D13	9.160	0.424	xx
D14	9.925	0.4245	xx
D15	10.658	0.417	xx
D16	11.300	0.410	xx

Driven Element details (in):

4NEC2 Patterns:

Comments are welcome!

contact Roger: email to

rgcox2 (at) gmail.com

Roger Cox - Spring Lake, MI