"the flowerpot antenna"

[dime196604]

I was looking for antenna designs in the net last night and one that cough my attention was this one that they called the flowerpot antenna?? I found it on one website but when i clicked the link it was in Italian so i used my web browser to translate and it just told me the page did not exist... So i googled it later on because it was stuck in my head and i found it on DXzone but it just said a few words about it not any thing on how to make it. But what i have read about it was that it is small and performs well for the compacted size .. So i just wanted to know if any one here has heard about this "Flowerpot antenna" and if so you know a web page with a design of it or know how to build it? And could you please pass this info on to me. please

[Night Crawler]

Flower Pot Antenna [Please login or register to view this link]

The flower pot antenna is just another stealth antenna design if you want to make one for 11 meters get a 102 inch whip stick it in a flower pot and use a counterpoise (ground radials)

[dime196604]

Th e one that i found on DXZONE did not have any vertical antenna it was all woung around the pot it just does not say any thing about how to make it. That is the one that i was try to find some directions to, if you have every seen any thing like that? But i do like the one that you posted to me. It seems like a good project that would work good as well and is a very sneaky way of hiding it. i live in an apartment and can't have no good antennas up here. i have a home made wire dipole on my deck i just don't think the landlord know that it is yet. Know one has said a word about it so i should just let it be wile i have the chance

[The Bastage]

Ingenious!

Are you looking to get on all the bands or just 11m?

I designed / built a disguise TV (CB) antenna years ago for a friend who lived in a CC&R zone and was only allowed to have a TV antenna 12' above his roof.

We faked a TV antenna from plexiglass and fiberglass rod and non-metallic gray primer paint, (about $20) then stuck it atop a 9' piece of thick-wall PVC tubing with a 106" wire inside soldered to the center of the coax which was running up from a roof vent up inside the bottom 4' of a larger diameter thick-walled PVC which supported the upper piece which housed the 106" wire inside & above it. It was 13' total but no one was counting inches.

Next we pulled four 108" "guy wires" which were attached to the shield of the coax, from inside the top of the 4' lower piece of larger diameter PVC, out through holes drilled in it, and they went out and down to the roof (at about a 120°angle for a 50ohm impedance) to insulators which were hooked to dacron line from the insulators down to the roof.
The 4 upper section "guy wires", (just under the mock TV antenna) were all dacron line so they were invisible to RF, but we put insulators in so it appeared uniform and professionally installed.
In the end he had an invisible home-brew Starduster center-fed dipole which KILLED the performance of the Wilson 5000 he had been using on the roof, and it worked perfectly until he moved 4 years later, and no one ever figured it out.

He sure talked a lot of DX with it and his TS-940S & TL-922 amplifier.

He did wait two weeks after installing it before he began to TX with power so it wasn't obvious.

One person did accuse him of having a CB in the van that he must be using in the subdivision (which was against the rules) and which must be what was ruining his TV & Stereo reception, so he showed him there was no radio hooked to the antenna coax hanging under the dash of the van, (his Kenwood TS-50 was hidden under the seat) then he grabbed the 4' firestik' antenna & snapped it off the ball mount as handed it to the guy saying,
"It's no good to me, I don't have a radio, it just came with the van and I never bothered to remove it. *SNAP* - Here, want it?"
He said the guy just spouted 'No Thanks' and walked off.

He had already decided the Wilson 5000 magmount was a better antenna and he just popped it on the roof once clear of the neighborhood.

I believe Federal law allows anyone to install a TV antenna 12' above the roof.

[Night Crawler]

Th e one that i found on DXZONE did not have any vertical antenna it was all woung around the pot it just does not say any thing about how to make it.

I took a looked at that one it's a Helical Wound Antenna using an L/C Network if your interested in making it I can calculate the measurements.

I believe Federal law allows anyone to install a TV antenna 12' above the roof.

That's true I have a copy of that statue somewhere they way they get around that here is the All Mighty and Righteous HOA will pay for basic cable tv to prevent you from installing a tv antenna.

By the way I like the fake tv antenna setup very sneaky.

[Kobo]

Flower Pot Antenna [Please login or register to view this link]

The flower pot antenna is just another stealth antenna design if you want to make one for 11 meters get a 102 inch whip stick it in a flower pot and use a counterpoise (ground radials)

That is so cool; I love sneaky things like that

[dime196604]

Any one els out there have any other GOOD stealth ideas out there? I am open to any thing

[drdx]

Here's a link to my base antenna, it is tree based, same idea. It has been up and running for a quite a while now.


[Please login or register to view this link]

-drdx

[dime196604]

So how does using coax for the elements on a antenna make it shorter i know at the ends you cross the center and outer shield.. would that be the same as making a wire dipole and just folding each leg in half to fit in to tighter places??

[The Bastage]

Here's a link to my base antenna, it is tree based, same idea. It has been up and running for a quite a while now.


[Please login or register to view this link]

-drdx

If you could get away with a bird house you could do a folded ¼ wave above another, center-fed, one around the perimeter of the bird house roof and the other around the base, fed in the middle.

if the bird house were ~2' cubed you would have 8 feet around and a foot up/down to the center (feed point) making a center-fed folded dipole. I can't speak to the efficiency of the radiation pattern but you might see an improvement in reaching further locally if it were mounted well above the rooftop.

I can't wait for someone to grow a 100' redwood then cut off the top and add a fiberglass fake top to the tree with fake branches as radials!

If someone marketed a 40' tall fiberglass redwood / pine (sporting an internal invisible 5/8) which appeared real, those installing it would ever have an issue again!

[ external image ] Is it against the rules to erect a balloon on a 100' wire, uhm, oops, I mean "ROPE"? [ external image ]

[drdx]

Well, the possibilities are endless whether it is mine or someone elses, but remember that in antenna land, there is no such thing as a free ride. An antenna's performance is going to be related to coax quality, location, and overall length/design. Don't expect a 5 foot flower pot based fishing pole with a curled up radial to perform well. It may be a nice quaint listening post but that's about it. My deal is a full quarter wave with a real buried radial system and works ok at best, but I'd hesitate to call it a real performer. Sure, I talk around and it has talked to other states with the right conditions but I'd put its performance at about what an average mobile has. A real base antenna 10 foot off the ground would smoke it, but it is all I can do invisibly for now. Once I have a tree that is about 5/8 tall, believe me, it WILL become my antenna structure but for now I'm at about 11 feet at best, a few years off from that.

If you're in an apartment or townhouse with a good gutter system I'd try to load that using an antenna tuner before I'd try some small flower pot deal, you'd probably have better luck.

-drdx

[The Bastage]

...seems like it might not also work as yours is working to have 3 guy wires tying up a smaller Scotch Pine, such as one you can buy around here for $45 and starts at ~9'-12' in the pot, using the guys as elevated radials, and if more height is required, add a fake plastic top to it with small enough wire to be invisible.

The only problem there is the performance will offer a little lower TOA which possibly might do better locally but yours is an ideal DX antenna for the more or less sporadic E we've been mostly experiencing lately on 10m / 11m.

I am just starting to help a local operator to build a 2 element Yagi folded into two 36" squares of masonite which we will be cutting & painting to make it appear as a new 'Digital' TV antenna grid, with fake bow-ties all painted flat primer gray to appear as metal, and hopefully we will be able to get the match down to a usable low SWR / reactance.

- If it performs fairly well I'll offer the dimensions here for others to enjoy.

[dime196604]

hey DrDx how would you use a antenna tuner with a gutter system? what would act as the counter poise? ans i have a down spout from the gutter system running next to my porch and i thought about having a horizontal 102" whip and then using the downspout as a ground system.

[The Bastage]

Well, I'm not Dr.DX, but for 11m you'd want two lengths of wire, about 8 feet 9 inches each, laying in your plastic rain gutter - one opposing the other, lust like the driven element on a Yagi beam / center-fed dipole, and feed it in the middle, one to the shield one to the center of the coax.

It should provide you with around a 1.5:1 SWR and horizontal performance in two directions.

If you have rain gutters running both diagonal and perpendicularly to the first, you could switch them around for different directions. The most expensive part will be a good switchbox like an Alpha-Delta.

[drdx]

hey DrDx how would you use a antenna tuner with a gutter system? what would act as the counter poise? ans i have a down spout from the gutter system running next to my porch and i thought about having a horizontal 102" whip and then using the downspout as a ground system.

If you did the gutter deal, you'd treat the gutter like a long wire, and have a counterpoise hooked to your tuner maybe. Your 102 idea is doable bue jeep in mind that a horizontal antenna will not be very effective to local vertical stations. This isn't a cut and dry deal, it really depends on your setup.

I like Bastage's idea if you have a plastic gutter. A dipole is a proven simple design. You may have to fiddle with the length of a dipole that close to other objects and structures, so cut it a little long so you can fold it back onto itself for tuning if you go that route. Edited in: Wait, what would you do when it rained?

If you can, post a pic of your outside area and I'm sure many will have other ideas.

-drdx

[Tobin]

I once disguised a 9up 9 down home made antenna under the eve of a rental I was living in. I ran my coax in through the gable end vent. The two 9 foot wires ran along the eve from the peak down towards the bottom of the peak. the gable end and eve was white. I left the white on the copper house wire and it was barely detectable. I spray painted all other exposed parts including the coax white. It was invisible unless you were near the peak which was 16 feet up..... When I left I pulled it down.

It worked well but you got to get the lengths right. I think the wires were cut 9 foot 6 inches but, I am not sure.....

[The Bastage]

I once disguised a 9up 9 down home made antenna under the eve of a rental I was living in. I ran my coax in through the gable end vent. The two 9 foot wires ran along the eve from the peak down towards the bottom of the peak. the gable end and eve was white. I left the white on the copper house wire and it was barely detectable. I spray painted all other exposed parts including the coax white. It was invisible unless you were near the peak which was 16 feet up..... When I left I pulled it down.

It worked well but you got to get the lengths right. I think the wires were cut 9 foot 6 inches but, I am not sure.....

Nice little inverted Vee! If you can get close to 120° between wires you'll see real close to a perfect match one trimmed to the right length. 9' 6" sounds a bit long for 11m unless you hung around well below Ch.1.

It's also a good idea to wrap 5 ½ turns of your coax around about a 4" former diameter as a common-mode current choke in the coax just below the antenna.

[Tobin]

Yeah Bastage, you are right.. I remember now. I cut 9' 6" and allowed 3" each ened for twisting and soldering. I never knew about the choke where you connect to the antenna. Can you elaborate on the wires being kept at a certain distance. I'd like to find a good diagram/schematic as I found the antenna wroked reasonably well but it needed tweaking. I am sure it could be made very efficient... I figured the directions I had were not complete....

[The Bastage]

Well, when you feed two ¼ wave length wires in the center, you have a 180° ½ wave dipole and if tuned for the least reactance it should be about 72ohms or 1.4:1 SWR (72÷52) and if you have a perpendicular ¼ wave radial @ 90° from the driven ¼ wave you should have about 37ohms impedance so you'll also have about a 1.4:1 SWR, however, if you place the two ¼ wave wires at a ~120° angle from the other it should net real close to a perfect 1:1 SWR.

Aside from the ease of raising only the center of an inverted Vee for, say, 80m (~120' total) that's a big reason why the popularity of that antenna design came about, easy to feed, decent performance, and almost a perfect 1:1 SWR when center fed & 120° angle direct with coax.

It's still a good idea to use a voltage balun at the feed point to help eliminate imbalances, plus wrap a common-mode choke in the coax to help stop the shield from radiating.
- For 10m-11m about 5.5 turns on a 4" diameter former, (PVC? plastic Coke bottle? NEVER USE ABS, contains carbon!) all wrapped neatly to make a single-layer tunnel / choke for the RF not to come down the feedline.

[The Bastage]

Here's a pic I found of a common-mode current choke:
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[ external image ]

[drdx]

Great advice. That one looks good but you would want to make it as part of your coax run itself, not inserted, and if the run is over 50 feet you'd want to run something lower loss like LMR-400, and with a choke 50 feet comes in there pretty quick. The flex works well for chokes and will prevent the coax from radiating on certain applications where it is a concern. For cb range, you only need about 6 turns, that one is a little better in that it would take care of lower frequency use, well down into the lower hf region.

-drdx

[dime196604]

what is the difference between a balun and a coax choke? how do you make the balun? or are they the same thing?

[The Bastage]

what is the difference between a balun and a coax choke? how do you make the balun? or are they the same thing?

A voltage balun acts like a differential transformer, helping to balance the load current to both sides since there's almost always an imbalance between the two ¼ waves.

A Common-mode-current choke is just an inductor wrapped from/in your coax which blocks RF from getting through and radiating / traveling down your coax shield.

[dime196604]

how does one go about making a voltage balun?

[The Bastage]

how does one go about making a voltage balun?

Here's some light reading which may shed a little more light on bayluns, uh, balloons, oops, uhm, baluns

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