Thinking about building a small ground plane for temp. use at other locations.

[Onelasttime]

So when I go up to my mother inlaws place a convient ground plane I can just chuck ont he ground for 10-11 meter use.


It will be built from stuff on hand. So probably 108" whip, some Francis 2 or 3 foot fiberglass wound antenna's as radials, some angle brackets, maybe some aluminium on a piece of plywood etc.... I amnot going to hual an antenna tuner with me and the radios I will be using will not have built in tuner.

I have not built an antenna tuning network into a home brew antenna before. When matching the homebrew antenna does the network always have to have capacitor and inductor?

To be honest and upfront I have not looked inside my ARRL HANDBOOK and I do not own their antenna book. I just thought I would toss this out. This way I can be in the wood heated garage and toss my coax through the dog and cat door and be toasty warm when visiting instead of in my wifes vechile with a magnet mount on top.

I amnot buying anything at all. I thought about magnetic loop but trying to run one that I could build with what I have on hand would be at the 100w input level would be diffacult and tunning would be a chore trying to cover 10m-11m. Plus constructing it in such a manner that it is compact and easy to take downa nd put up would be an issue.

Oh I live in Michigan and once snow flys anything that you need to anchor to the ground or drive into the ground is a no-go. The ability to just set it on the ground and go is a huge factor. On top of that it would also allow it to be tossed into an attic, onto a balcony, onto the beach, in front of your sofa or bed almost anyplace that a 108" SS whip wont hit when placed upon the floor.

Down the road I want to build a magnetic loop just to do it. I have built plenty of Dipoles but those are a pain for stealth use when traveling. I know my homebrew should be able to outperform that dreadful FireStik indoor base antenna but that is kind of the idea though. Obviously the 108" SS whip could be replaced with a teloscopic antenna for the best portability.

What I have kicking about:

2x 108" MFJ SS Whip Antenna
4x Francis 11m fiber glass whip antenna
3'x3' aluminum sheet 1/8 inch
lots of solid copper Romex house wire to use to make inductor
lots of jelly bean electronic parts but would happily purchase specific capacitors if need be
lots of hardware and scrap lumber and plywood

My bigest concern is that the built in matching network be able to live outside with the antenna in all weather from 98°F Summers to -28°F Winter and all manner of percipitation!

If someone has already tackled this a ready plan to follow would be great with known proven outcome but it is the matching network that I am really in an area I have not played with before.

P.S. I do intend to dust of my ancient 1999 ARRL HANDBOOK and see if the info I need is inside of it.


P.P.S. Thanks in advance!

 

[AudioShockwav]

One option is use two whips and make a dipole, get it up in the air.
Eliminates the ground problem.

73
Jeff
image shamelessly ripped off the web

 

[brandon7861]

If you get the impedance at the antenna feed pint (not at the coax input, but at the antenna itself) into this green region, you can to it without a capacitor.

However, unless that impedance is on this line, it will also require the vertical element be on an insulator.

For an impedance in the green area, there will be an inductor from the coax center to ground, and also from there, to the vertical element (hence the insulator). This is usually a single coil from ground to the vertical element with the center conductor at a suitable tap point. Knowing the feed point impedance will allow you to calculate the coil dimensions and the tap point.

In the second image, the coax center is connected directly to the vertical element (no tall insulator) and the inductor will go between that and ground.

All other situations involve either an inductor and capacitor, or only capacitors., The green is what you want to aim for but the insulator might be tough to find. You may have to MacGyver one.

The insulator doesn't need to be tall. Technically, the part the whip screws in will work since it is already insulated from ground, its just a lot nicer when the coil is wrapped around the insulator itself and not the whip.

 

[BJ radionut]

 

[Onelasttime]

View attachment 70810One option is use two whips and make a dipole, get it up in the air.
Eliminates the ground problem.

73
Jeff
image shamelessly ripped off the web

I considered doing dipole out of dual whips. Why? Because It is not wire I have to hang, slope, invert, etc..... I do have two large Saturn Aura rims with light lip damage. I could mount a plate to that and slip a pole in and bolt antenna to. It would be heavy and take up some trunk space but would be portable and easy to set up and take down.

 

[Onelasttime]

So I am on the right track. I figured I was not too far off but that was assumption on my part. I use a tuner in my house but it is the size of a boot box not what I want to lug around. I figured same parts of fixed value would need to be in the circuit but nice to know it is not impossible to maybe get there with out absolutely having to wind inductors. Sure that withthe help of you guys I can figure it out.

I have not had time to look into things any deeper. With Winter and snow not to far off I am trying to get car's for me, wife and twins still in college up to date on maintenance and winterized, garden and yard under control, and all the other must do stuff down like fixing my snow blower etc....

Radio is my hobby as is home audio so those projects always come last! LOL

 

[AudioShockwav]

I built this in about 20 min, two Francis 96" whips, a piece of flat stock, two mobile whip mounts, just for grins this morning.
First key got me West Virginia with 100 watts on ten meters SSB mounted vertically.
With my little LDG autotuner it easy covers 10-15 meters.
Direct connection with no tuner shown on my old MFJ.
It works, simple and fast.

73
Jeff