I was just wondering, if I get a pizza pan (or any metal disk) and solder a lead to the center, would it act as an antenna for resonant wavelengths?
It occured to me this might be a way to receive signals over a 360 degree polarization range.
Is it a simple as that, or am I being simple?
Would it have any detracting features compared to a dipole, in terms of efficiency?
Mark Newman
What are you using as the earth plane? You need to consider the whole circuit, not just the 'hot' lead.
-- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
Ummm... you might have some problems soldering to an aluminum pan.
You could turn the pizza pan into the top part of a discone antenna: which is very broadband and omnidirectional.
Ummm... polarization is vertical, horizontal, circular, or eliptical. Any antenna will work with all of these, but if there is any cross polarization, there will be some losses.
You're being too simple mostly due to lack of any numbers. Kindly disclose:
Yes. The rule of thumb is that you can have: - large bandwidth - small physical size - high efficiency Pick any two. For example, you can have a fairly small wideband antenna, but it won't be very efficient. A dipole is physically large, is quite efficient, but doesn't work over a wide range of frequencies.
Here's we go. A pizza pan antenna: also known as a capacitive hat.
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Oops. Please change the "high efficiency" to "high gain".
2:30 AM. No brain.-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
Don't worry. I have bolts. Anyway, I would never use aluminum for cooking.
I have seen antennae designed specifically for OFDM that are mounted at a 45 degree angle off the mast. Surely, there is some relationship between the geometry and ability to pickup signals at various polarizations.
The idea of a pan was to have a 360 degree polarized dipole. Maybe even an ellipse for two resonant wavelengths.
Yes, I suppose I should just try it, over a metal roof for the ground plane. Or how about the disk with a peripheral wire all around its edge as the ground plane. Just thinking out load here. What do you think I might expect.
Still uses a resonant winding as far as I can tell.
Mark Newman
Soldering to aluminum is pretty easy once you know the trick. We've discussed it here before.
The problem is that aluminum oxidizes so quickly that the oxide blocks metal-to-solder contact. The trick is to scratch through the oxide through the hot solder, which gets the solder through to unoxidized aluminum. Once you've gotten under the oxide, you're home free.
Some people use a puddle of something (e.g. flux) to get the same result, but just scratching through a solder puddle works too, IIRC (it's been a while since I tried).
Home Depot sells Al solder with a flux that does the same, IIRC.
Cheers, James Arthur
On a sunny day (Sat, 03 May 2014 02:29:41 -0700) it happened Jeff Liebermann wrote in :
When it storms, a plastic pipe, how far could it fly? Would it be mistaken for a flying saucer?
I dunno about the weather there, but here after a storm I sometimes have to re-align my sat dish, and that is bolted to the wall with heavy iron.
Whole fence blew over this winter.. Wooden poles just broke.
I have a 27 MHz GPA, its down now, anti lighting measures, the second one, even that simple thing has seen storm damage.
Not very far. The lift to drag ratio of the pizza pan is terrible. It would do better rolling on the ground.
No. Flying saucers are apparently designed to travel between planets in a vacuum. They don't do as well in an atmosphere. Flying pizza pans might do better, but have very limited payload capacity.
In the distant past, I serviced radios on Santiago Pk in the Orange County CA area. The wind on the mountain tops can be really strong. I've send inverted camping tents, one dish antenna, corregated roofing material, and plywood sheets flying through the air at 1500 meters elevation. Sorry, but I haven't seen any pizza dishes or flying saucers. I believe the local record was a 3 meter dish that was conveniently found blocking the road about 10 km away from the peak.
Try an inflatable DBS dish design. Just let the air out when the wind blows, and re-inflate it when it's safe. If your dish is motorized or articulated, you might consider feathering it, which means point it straight up or down for minimum wind resistance.
Incidentally, radomes don't always help:
Welcome to the dark side. You cannot fight the force. I suggest you either build your fence to bend over in the wind using rubber or spring loaded fence posts, or build it from material that you can afford to have blown away. For example, a fence made from cardboard or urethane foam board and posts.
Antennas need to be designed to fight the force, even though in the long run, the force always wins. This is for yagi antennas, but the principles involved should work for your CB ground plane.
For Learn By Destroying(tm) inspiration, see:
-- Jeff Liebermann jeffl@cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
On a sunny day (Sun, 04 May 2014 08:29:08 -0700) it happened Jeff Liebermann wrote in :
Play ball..
Looks nice in the Christmas tree..
Yea, well I did read RSGB handbook when I was younger...
Nice picture of burning smilde tower, radio was out country wide for a while here.
Just ordered two of these eBay item number: 251360001937 150W DC-DC Boost Converter 10-32V to 12-35V 6A Step-Up Power Supply Module
5 dollar 28 cent a piece, free shipping of course, tried to design one cheaper, no way, the caps cost more, this will power laptop and monitor on a boat so I can receiver RF weatherfax (hamfax). I actually have that and opencpn (navigation) running on a Raspberry Pi, bit slow though, but nice low power.. The other interesting experiment I did was use a normal shortwave receiver at 4610.0 kHz and 8040.0 kHz and beat against it with the raspi PLL to get SSB weatherfax... works, but will use a real SSB receiver anywaysAll in all a good satellite phone with data is a lot simpler, maybe even cheaper (about 600 Euro Immarsat) in the short run. Now about storms...
James You mean to say you can solder to Auminum using tin-lead solder and 'scratching through?"
If so, that's a new one on me. Be curious to hear. (Harbor Fright sells an Al solder which gets good reviews.)
TIG welding uses an AC current to "clean" the aluminum as you weld under Argon. I have a DC TIG machine, about the size of a toaster, that goes to 150 amps.
I've always wondered if it could be retrofitted to put an AC signal with the DC one. Shouldn't that be easy to do? Would a blocking diode be necessary on the DC supply?
I've been thinking about that also, as I'm having such a welder too.
There are two possibilities in my view.
1 Parallel, which is undoable, as the AC welder's transformer would effectively short circuit the DC of the TIG welder. Only solution to that would be to put a _HUGE_ capacitor in series with the AC welder, which is impractical (nicely put).2 Series. Even with a series diode, the TIG welder would see huge variation in voltage on its terminals, and will be 'fighting' with the AC transformer's voltage to maintain its set current during the times the diode _would_ be blocking.
So, no, I don't think it's feasible. Buy a new TIG welder, if you want to convert to serious Alu welding. You _could_ try to use your DC-only welder, if you'd first very seriously clean up your workpiece.
How about ultrasonic breaking of the Alu-oxide?
I never had any luck with the scratch technique. Aluminum flux is all you need. I tried with a bunch of different Al alloys and different solders.\ Everything worked just fine, even Al foil.
George h.
La-co aluminum flux is all you need. I bought some "fancy" Al solder...Tin-Zinc from McMaster-C but the flux also worked Sn/Pb and the low melting point silver solders...silver and tin?
George H.
Yep. Dedicated flux might be easier, though.
==== ===== >> Ken Dunlop wrote: >>> What are the alternatives for applying an earth lead to a bare aluminum >>> chassis that do not require a mechanical fitting? > >I successfully soldered regular PbSn solder to aluminum by scraping >vigorously under a drop of engine oil and then quickly soldering in >the oil drop.
I have been using that technique for over 50 years without the oil. It takes a lot of heat because the Aluminum conducts the heat away fast. Rub a blob of solder vigorously with a hot iron until it bonds. Then solder whatever to the blob.
You can also flame weld Aluminum but it requires a talented craftsman.
John Ferrell W8CCW ==== =====
Can't miss with that.
That's a pretty hot toaster. It's not clear what you're hoping to do though, why or how, or what the base unit already does.
Cheers, James Arthur
I've used the "Alumiweld" rods someone else mentioned, Zn-Al-Mg, in various combinations IIRC. They're actually solder / brazing rods, but work very well. Stronger than the base material (much), low-temp. No flux.
Caveat: the various websites warn that certain of these rod alloys suffer wicked galvanic corrosion.
Cheers, James Arthur
Check out biconic antennas while you are at it.
?-)
'scratching
an Al
Yep. I did that something like 40 years ago to modify a clock by placing regular electronic components on the ends of shortened hands.
?-)
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.