Desktop Discone position...metal or not?

[TrackMyTrunk]

Hi everyone.

I've recently purchased a Skyscan desktop discone to be used in the bedroom. It's impossible for me to gain access to the loft OR to get a discone up on the roof due to the building layout..so it's desktop or bust i'm afraid! But can somebody please tell me out there, would it be best placed on metal? And if so, roughly what size in diameter or depth, is bigger the better or doesn't it really matter. Would I defo get an improved signal on metal??

Please reply if you can answer.

Thanks.

 

[DPD1]

Nope... It doesn't need a ground plane. Just find the spot it works best.

 

[KI6ABZ]

Discones are funky because of the way they're designed. The angled radials reflect the signal up in to the horizontal radiators. The slant allows the signal to find its natural resonant wavelength, which is what gives discones their incredible bandwidth.

But because of that, I think the gain is going to be concentrated in a relatively flat circle around the antenna; unlike a vertical mast, you shouldn't see a lot of effect from something underneath it. You may see some effects from something above it, though, since metal above the antenna could reflect a signal down on to the radiators. (Remember that the horizontal elements on this antenna pick up the signal, unlike most vertically polarized antennas, where the vertical element picks it up.)

Keeping all that in mind, you can certainly play with locations; it may be that putting it on or above a desk at an even fraction of a wavelength helps the signal, but since the reflectors are already longer than 1/4 wave for the lowest frequency you're looking for, I don't think you'll see any real improvement.

However, the proof is in the pudding, as they say: experiment. Try different places. You can even try opening a window and hanging the antenna outside. You'd be surprised how much better my RH77 performs outside the window on a simple bracket...

 

[TrackMyTrunk]

Many thanks KI6ABZ for ALL your well expained info..EVERYTHING taken on board. And there's me munchin' through all the biscuits like there's no tomorrow thinking i'll need a decent sized tin!!! (sorry that should read cookies shouldn't it from your part of the world!)

Thanks again for taking the time.

 

[TrackMyTrunk]

Ok thanks DPD1..appreciated.

 

[KI6ABZ]

Biscuits, cookies, it's all the same.

Actually, I don't know as much as I pretend, but I can parrot stuff I read elsewhere very well. I read up on discones back when I got in to amateur radio; I did the research to find out why I would use a Discone instead of a vertical, and I was very curious about how they could possibly have that kind of bandwidth. If it turns out later that I'm full of manure, I blame Wikipedia!!

Discone antenna - Wikipedia, the free encyclopedia

or, put another way: I don't know crud, but I Google VERY well!

 

[kb2vxa]

Rule of thumb: Mobile antennas use the vehicle body as the ground counterpoise so when used as a base antenna one needs "ground replacement" such as setting it on a baking sheet, filing cabinet, refrigerator, etc. Base antennas have built in counterpoise and must be kept clear of large metal objects to avoid (pickup) pattern distortion.