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Simply copy a design as someone above suggested, unless you are really interested in understanding the how and the why, I wouldn't bother worth the ARRL antenna manual ;)

DB, here's an example taking it to an extreme, I use a Scorpion SA680 on my car, fully retracted it is around 1/4wl on 10m, however fully extended on 80m it is no where near 1/4 wl, so it is a shortened antenna on an inadequate ground, we are probably talking single percentage points efficiency...

Evening all, just to add my two penneth (2 cents) the whole discussion about a 1/4 wl antenna having 35 ohm impedance came about asa result of one respondent suggesting it was 70 ohm, so I chirped in with the 35 ohm response, little did I realise what would follow, however I'm currently...

The angle of the radials on a GP antenna affect the impedance, horizontal ground planes would produce an impedance around 35 ohm, radials at approximately 45 degrees down will have around 50 ohm and of course a vertical radial (as in a dipole) will have around 70 ohm impedance. Because a car...

I don't believe the statement to be incorrect, especially when he goes on to clarify: And, to repeat, if your HF antenna doesn't require matching to provide a low SWR (with the possible exception of 10 and 12 meters), then you need a better antenna, a better mounting position, or both...

I was very lucky to find one here in the UK, they work out around $1500 to buy here due to shipping and import charges, if I ever find myself in a financial pickle I'll sell an organ before I sell the Scorpion :blink: In answer to whether they can be painted, I don't see why not, Scorpion...

Ham fisted lump, the way he just lobbed the gear in the foot well, was it supposed to be a comedy sketch? Anyway, they were small HF mobile antenna, for a big antenna you need a big mount:

Rather than cover what others have said, I'll ask a question, what is it you are hoping to achieve?

Just thought I'd drop a line to say I haven't forgotten the project, time is not something I'm endowed with at the moment, currently working six 12 hour shifts a week means I'm certainly not going to do anything this month, however I've got a couple of weeks leave coming up at the beginning of...

Excessive common mode current will completely shut down an IC7000, when I said flicker if you can imagine what tvi looks like and then imagine what that would look like on the colour display of an IC7000, that's what I mean by flicker :ohmy:

I use toroid chokes on my portable 1/4WL 20m vertical, I used one on my 10m 4ele beam, and on my 3 element triband beam, I also used an air wound choke on my Hustler 5BTV, however that was before I realised it's limitations and suffered bad common mode on 40/80m. I don't use these antennas...

No myth or kidology, but a good source of tested data: Common-mode chokes

I use the SY27-4 here, no complaints working the pacific from NW England, beating many W6/W7 to a rare one too, North Cook Islands last Autumn, very happy with it ;)

A couple of pictures I should have added at the time: 20m 1/4WL attached to the tow hitch on my car, you can see the need for a shortened antenna. And a large capacitance hat in use on the 40m band. I must stress I'm not trying to convert anyone to amateur radio :whistle: I...

I would consider centre loading before base loading, see if you can get hold of a second hand hamstick, it doesn't matter which band because you'll be stripping it down anyway, but if you can find a 10m version then less wire to remove. Fabricate a large centre loading coil from copper brake...

The longer shaft everytime, not that I own a Predator, now here's the thing, the closer the coil is to the vehicle bodywork the less efficient the coil is, this is due to greater capacitive coupling of the coil to the vehicle body, however when you raise the coil away from the car body it's...

It's actually been really nice here today, perfect antenna testing weather, however I'm finishing the interior decorating today as my relatives from CA are arriving tomorrow morning, so that will be another couple of weeks without radio, maybe I can rope my cousin into testing the antenna with...

There was a slight wind when I carried out the tests and as the antenna was loaned to me there were no mast clamps supplied, so I used what I could find, any movement of the antenna was directly acting on the analyser plus there's every possibility the connection wasn't tight enough and created...

Some of the other tests I want to carry out are using a non conductive mast so that I can rule out any capacitive coupling between the antenna and mast, carrying tests out with an electrical 1/2WL feeder, this will prove if the feedline does indeed affect the results, the coax I used was just...

You're drawing me in like a moth to a flame, here are three plots that show the bandwidth, the vertical lines indicate 2:1 VSWR, and ignore the data points on the images with 18" coax and no coax: No coax attached 18" coax attached 24' coax attached Here are some of my findings...