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Plated antenna elements

Jan 28th 2016, 21:44

WA1DF

Joined: Dec 9th 2012, 20:14
Total Topics: 0
Total Posts: 0
I am looking for any documentation concerning antenna elements that have been plated with a different metal. For instance: Aluminum radials that are plated with copper or silver. This could be on radials for directional antennas, or even on simple dipole wire antennas.
I am certain that skin effects will change as well as resistivity/impedence also resonate lengths.

Any references to this kind of data is appreciated.
Jan 29th 2016, 00:17

KC6VVT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Tinning is a form of plating that I used to use with some success on new aluminum clad steel antenna wires (8/10 AWG Solid) that were captured bya grooved 2x2" aluminum plate at the top crossarm of a special HF antenna element. The wire product name was Alumoweld® (like Copperweld®) and had to be replaced periodically in overhaul due to salt air corrosion destroying the aluminum coating. We used Penetrox brand aluminum/copper joint compound inside the joint and on the tinned wire, and sealed the edges of the 2x2 plate with RTV Silicone rubber, as this was an important joint. Using the same type of aluminum solder with flux, the top of the wire was formed to the cleaned to bright aluminum channel crossarm and soldered for electrical bond. The commercial solder and flux was called 509, and cannot remember where we bought it, but a good electrical supply house that sells aluminum or alumoweld wire should be able to get it and penetrox for you. 73 de Pat KC6VVT
Feb 1st 2016, 15:59

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
While EZNEC won't handle plated materials, you can use the demo version to calculate the resonant length for different materials

https://www.eznec.com/demoinfo.htm

Zack Lau W1VT
ARRL Senior Lab Engineer
.
Feb 2nd 2016, 02:54

WA1DF

Joined: Dec 9th 2012, 20:14
Total Topics: 0
Total Posts: 0
Thanks Pat & Zack, I thought it would be interesting to do some experiments with different plating techniques. For instance, could the bandwidth (broader) of a radial of copper coated aluminum look like a huge cross section of a solid copper rod? Also, would the angle of radiation change if the top and bottom of the radial were aluminum and the side were copper plated, perhaps yielding a lower angle of radiation?
I don''t think existing simulation programs could simulate these conditions.

Feb 2nd 2016, 14:06

AA6E

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
If you want to estimate the effect of plating on RF characteristics, you need to know the skin depth (the depth to which RF currents penetrate in a conductor) and compare that with the plating thickness. The formula for this should be found in the Handbook or online. It depends on frequency and on conductivity of the material. If your plating is more than a few skin depths thick, you can ignore the base material, so far as RF is concerned.

I think the main reason to consider plating is for corrosion properties, however. Building an antenna out of gold or silver plated components may look jazzy, but at best you reduce your losses by a small amount. (It's more significant at UHF / microwave frequencies.) It will not increase your gain or change your radiation pattern much at all. If it keeps the elements from decomposing in the weather, though, it could be a good deal. Gold is great for this, but it's not the cheapest solution!

73 Martin AA6E
Feb 2nd 2016, 17:50

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0

http://www.ansys.com/Products/Electronics/ANSYS-HFSS
An Introduction to HFSS: Fundamental Principles, Concepts ...
ANSYS makes no warranty of any kind with regard to this material, including, but ... Initially used to model waveguide transitions, HFSS was quickly utilized for ..... the solution space are covered, or coated, by a perfect electric conductor bound-.

There are 3D finite element analysis programs that can model plated or multilayer conductors.

Zack Lau W1VT
ARRL Senior Lab Engineer
Feb 7th 2016, 04:53

WA1DF

Joined: Dec 9th 2012, 20:14
Total Topics: 0
Total Posts: 0
Thanks Martin and Zack, I have downloaded the EZNEC software and I will do some experimenting. The HFSS looks to be beyond my understanding but I will look into this too.
Gold plating might be a bit too expensive and ostentatious but silver can be inexpensive especially if you use old antique silverware as your anodes for plating. hi hi..
I enjoy thinking outside of the box on antenna designs so you just never know what you might trip over in the process.
73's WA1DF Don

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