January 2015 Copyright 2015

Contesting with Verticals & VDAs

Pete VE3IKV / VA3RA / VP2EAT

January 2015 Copyright 2015

Contesting with Verticals & VDAs

• “Verticals” means both gain-type HF monoband verticals and vertical directional arrays (VDAs)

• Object is to keep the main vertical radiation pattern as low as possible (<10 degrees) in order to maximize F2 signal propagation & signal strengths

• Simple trap yagis, spiderbeams, etc. low to the ground have a much higher radiation angle, and therefore substantially less gain below 10 degrees

• Simple monoband VDAs can also provide additional gain, and an even lower radiation pattern when near salt water, or when elevated with a clear horizon

• Omnidirectional pattern (or hemispheric pattern with VDAs) may be useful during contests, since a rotor is not necessary

January 2015 Copyright 2015

• What is a “gain” monoband vertical?

• When properly matched with a low-loss network at the base, and using an extended 0.64 wavelength radiating element, and four 0.67 wavelength radials sloping at 45o, the monoband vertical will have:

approximately 5dBi omnidirectional gain

a low vertical radiation angle of approximately 8 degrees above the horizon

a 50-ohm source impedance with low VSWR

• A matching network of 5/16” copper refrigeration tubing wound on a section of 4” diameter plastic septic drainage pipe makes a very low-loss matching network

Contesting with Verticals & VDAs

Gain Monoband Verticals

January 2015 Copyright 2015

Contesting with Verticals & VDAs

• 0.64 wavelength produces the maximum gain before the radiation pattern begins fracturing into multiple lobes (2x = old “extended double zepp”)

• The 0.64 wavelength “gain vertical” open-coil tapped matching network is inherently grounded, so as a result the antenna exhibits:

very low noise,

the VSWR is not affected by rain, and

it has rejection of out-of-band signals due to the tapped matching coil design

voltage maxima is at a higher physical height than a ¼ wave vertical (a 10m 0.64 wavelength radiator = 22 feet vs. 10m ¼ wave = 8.2 feet) – less RFI at rig as a result

January 2015 Copyright 2015

Contesting with Verticals & VDAs

Monoband 0.64 + 0.67 WL radials vertical pattern

January 2015 Copyright 2015

Contesting with Verticals & VDAs

10m 0.64 WL monoband gain vertical at VP2EAT

January 2015 Copyright 2015

Contesting with Verticals & VDAs

10m 0.64 WL monoband gain vertical at PJ7/VA3RA

January 2015 Copyright 2015

Contesting with Verticals & VDAs

10m 0.64 WL monoband gain vertical at FJ/VA3RA

January 2015 Copyright 2015

Contesting with Verticals & VDAs

Year 1: Results using a 10m monoband 0.64 lambda gain vertical:

2011 – TOP CQ WW DX CW SOSB/10 LP

• 9J3A...........1,403,506 (S53A)

• HP1WW......1,166,400 (OH0XX)

• J28RO............800,382 (F5IRO)

• C4Z.............. 702,150 (5B4AIZ)

• 5C5W.............642,432

• VP2EAT.........508,599 (VE3IKV)

….notice all the 3-pointers!

January 2015 Copyright 2015

Contesting with Verticals & VDAs

2012 – TOP CQ WW DX CW SOSB/10 LP

• C4Z.................600,134 (5B4AIZ)

• UK9AA............481,664

• VK9/OG1M......376,263 (OH1VR)

• HQ2N..............373,524 (JA6WFM)

• PJ7/VA3RA....369,930 (VE3IKV)

• VK6AA............355,840 (VK2IA)

….notice all the 3-pointers!

Year 2: Results using a 10m monoband 0.64 lambda gain vertical:

January 2015 Copyright 2015

Contesting with Verticals & VDAs

Year 3: Results using a 10m monoband 0.64 lambda gain vertical:

2013 – TOP CQ WW DX CW SOSB/10 LP

• NP3A...........1,060,352

• FJ/VA3RA......625,664 (VE3IKV)

• N8II.................434,000

• C6AZZ............430,000 (KQ8Z)

• OK1FDR.........408,519

• WB4TDH.........344,998

……still all with only a keyer & a paper log!

January 2015 Copyright 2015

Contesting with Verticals & VDAs

Vertical Directive Arrays (VDAs)

• Used by recent DXpeditions TX6G, T32C, VP6DX,

FT4TA, etc. rather than low horizontal yagis (10-20m)

• The VDA is a 2-element ½ wave yagi in the vertical

plane, with a wire dipole driven element and a wire

reflector behind it

• Broad 139o beamwidth in the horizontal plane

• Low 7o elevation angle in the vertical plane

• 8dB gain relative to a low horizontal beam reported

when used over sea-water wetted sand, or when used

elevated over normal ground

• 30dB null at the rear (!)

January 2015 Copyright 2015

Contesting with Verticals & VDAs

The 2-el wire VDA

Forward direction

January 2015 Copyright 2015

Contesting with Verticals & VDAs

BAND MAST BOOM LB HB LF D/2 R/2 DS RS d1 d2

20m 12.5m 4m 1.78m 6.24m 6.0m 4.77m 5.07m 0.46m 0.42m 1.62m 1.51m

17m 10m 3m 1.39m 4.87m 4.6m 3.69m 3.97m 0.37m 0.33m 1.30m 1.19m

15m 10m 3m 1.19m 4.45m 4.2m 3.18m 3.40m 0.31m 0.28m 1.09m 1.01m

12m 8m 3m 1.01m 3.91m 3.7m 2.70m 2.88m 0.26m 0.24m 0.91m 0.87m

10m 8m 3m 0.89m 3.66m 3.4m 2.39m 2.55m 0.23m 0.19m 0.81m 0.67m

2-el VDA dimensions for each HF band - 20m to 10m*

* Courtesy G3WGN & G3SVL

January 2015 Copyright 2015

Contesting with Verticals & VDAs

The 2-el wire VDA has approx 30dB F/B ratio!

January 2015 Copyright 2015

Contesting with Verticals & VDAs

2-el wire VDA cardioid pattern in the horizontal plane

January 2015 Copyright 2015

Contesting with Verticals & VDAs

VSWR plot for 12m version of VDA

January 2015 Copyright 2015

Contesting with Verticals & VDAs

• If you don’t have a conductive salt-water ground, elevate the antenna as high as possible in order to get a clear path to the horizon, otherwise you will get reduced performance

• For use at the beach, the following are the min. recommended heights of the boom above ground:

20m – 6.24m; 15m – 4.45m; 10m – 3.66m

• Away from the beach, raise the boom as high as you can

• Boom and support mast must be composite non-conducting material

• Coax feedline should exit the boom at the center, at a 90o angle for at least 1 wavelength before dropping to the ground. Ferrite common-mode chokes may be necessary on the feedline.

January 2015 Copyright 2015

Contesting with Verticals & VDAs

20 meter elevated ground-plane vertical at CY0X - 2008

January 2015 Copyright 2015

Contesting with Verticals & VDAs

Thanks – any questions?