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Author Topic: Balcony Apartment Stealth Antenna  (Read 5618 times)
VA3API
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Posts: 66




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« on: November 15, 2000, 10:24:10 PM »

I live in an apartment condo am having trouble getting a match using Comet Whip mounted to the balcony.  Poor match an poor signal reports.  Anyone have any ideas here??

Kevin VA3 API http://www.corpa.com
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KF4BOT
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Posts: 34


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« Reply #1 on: November 17, 2000, 06:44:14 PM »

My antennas are on my balcony. I use 2 homebrew loaded vertical dipoles. One for 10 & 12m, and the other for 15, 17 & 20m. I use an antenna matcher. In most cases I get a flat SWR. The worst I get is 1.5:1 on the WARC's. The matcher that I use is a Kenwood AT-180 that I picked up used at a hamfest. I didn't do too bad with a homebrew matcher either. As for your whip, you need something to ground it to. You can connect the coax shield to the balcony railing if it is metal. If not, use a 1/4 wave counterpoise and connect that to the shield. Fact is, even if the balcony railing is metal, the counterpoise wouldn't hurt, and it may help.
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AC0X
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Posts: 24




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« Reply #2 on: November 22, 2000, 04:35:46 PM »

If you're going to use a short vertical as a stealth antenna, there are some things you HAVE to do to get a decent signal out:

1)GET A GOOD GROUND. Your antenna needs somehow to be a two-legged animal. If it's a dipole, each dipole element is a leg. On a vertical, your ground is a second leg. If your ground isn't good, your antenna won't perform.

2) MINIMIZE LOSSES. Even if you can get your tuner to get a 1:1 match, if the match at your antenna is too high, you're still potentially losing a lot of signal. Remedy this by getting your feedpoint SWR as low as possible, use as short as a coax run as possible, and use LOW LOSS coax. Since you probably don't run a lot of power you may think you can use a lesser quality coax, but remember lesser quality coax has a higher loss with high SWR conditions.

3) GET THE VERTICAL IN THE CLEAR AS MUCH AS POSSIBLE. I know this is probably tough since if it's in the clear, it isn't very stealthy. But look around at your situation, and see if you can move it. At least get it away from any metal that may act as a "shield".

Good luck.
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N4ZYV
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Posts: 90




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« Reply #3 on: November 26, 2000, 02:27:29 PM »

I once used a magnet mount antenna on a second floor balcony using window screen for the ground plane. I got the metal variety (fiberglass is very common but won't conduct). Layed it on the balcony floor, layed some outdoor carpet over it. Cut a hole for the antenna base to contact it directly and it worked fine (well, there is only so much you can expect from such a setup). I only used it on 10 meters on HF.
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K4IA
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Posts: 66




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« Reply #4 on: December 02, 2000, 05:05:56 PM »

The MFJ 934 is designed for this problem.  Combo antenna tuner and artificial ground.
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WB6BYU
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Posts: 13038




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« Reply #5 on: December 11, 2000, 01:05:39 PM »

I've used a mobile whip mounted horizontally, with an aluminum
window frame as the ground.  Fortunately, the window frames
throughout the building were connected together, and it worked
quite well.
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KA3VVV
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Posts: 0




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« Reply #6 on: December 24, 2000, 10:56:07 PM »

You can use a DK3 screwdriver ant un your apt for 10 thru 80 woke good for a apt ant. don't need a trunner. The ant only cost $160.us.It a mobil ant  but it work.
here is his phone number 530-787-3905 Don Johnson w6aaq. gie a call talk to him he will help.
 I had one up @ one time I now have a dipole up useing thin wire have one up for 80,40,10 use ant truner for other .
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N6AJR
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Posts: 9891




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« Reply #7 on: April 27, 2001, 06:57:47 AM »

My strongest reccommendation is to make up and use a counterpoise for the frequencies you are using.  You can do this real easy by using a length of antenna rotor cable.  

If you buy a 50 foot long piece of 5 wire, you can connect the left end  wires number 1,3,4, and 5 to a common ground. Join the right end of wire 1 and 2 together. now measure in about 16 feet 5 Inches from the right end ( making a total of 66.5 feet ..50 + 16.5) and cut a little window out of wire # 2 to break it there. Wire #3 is cut  out at 33 feet and a inch or two, wire #4 is cut at 16.5 feet and wire # 5 is cut at 8.5 feet. You can just leave the "unused " pieces of wire where they are , or figure a way to strip them out.  These are all cut a little long so you can trim each wire to resonance on your particular frequency of desired use. This whole piece of rotor cable can then be run around the room or under the carpet, or hung out the window  and the other end ( left end) with wires 1,3,4,5 tied together is hooked to the ground on your antenna tuner or back of radio.

If ya hook it there, it is a counterpoise. If ya hook a second one just like it to the bottom of the antenna ( outside or ground side of the connector) it becomes a set of radials.  If ya hook two of them together and hang them in the attic feeding one side with the center conductor and one side with the outer conductor of a piece of 50 ohm coax you have a pretty good low power ( say up to around 100 watts) dipole antenna, with the 80 meter portion being a partial folded dipole. Tape up any where there is exposed conductor at the end away from the radio as there can be some awesome voltages present.. a couple of wraps of #33 electrical tape will work.

So now you know the secret to the best use of rotor wire, although some one told me it works ok for running antenna rotors too...

If you use the 8 conductor wire and cut a couple of them side by side for your favorite bands , one a little short, one a little long, the radio sees it as a wire with a really big diameter...

This is not my idea, It has been around a long time but that is because it works.. good luck

tom
N6AJR

P. s. If you are left handed then reverse the ends ..Hi HI




1  ------------------------------------------------------------------------|
2      ---------------------------------------------------  ***  ---------------|
3  ------------------------------------------  ***  ------------------------
4  -----------------------------  ***  -------------------------------------
5  -----------------   *** -------------------------------------------------


<- join this end of 1,3,4,5

                   ...................   join this end of 1 & 2 ->

remove a little window of wire where the ***'s  are.

<-- this is the end you attach to radio ground  etc.
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KF6RDN
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Posts: 39




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« Reply #8 on: June 01, 2001, 12:12:30 PM »

As one guy mentioned, I'm using the don johnson DK3 with a 102" CB whip ala radio shack.

Picture one of those long fishing gaffes(sp?) made from 2 5 foot mast sections (again RS special) The "hook" is setup on one end, with the DK3 extending from that.
Slap th 2 masts together hook the thing on the rain gutter , the hook digs into the metal rain gutter becomes conterpoise, the rest of the mast becomes a counterbalance (to keep it from physically toppling)

It's not as stealthy but it is definatly temporary which also satisfies most cc&rs. Most make mention of permantant fixtures.
One thing is I need more weight for the counterbalance should it get windey.

I've heard mention of people filling pots for plants with cement with a piece of PVC pipe for a sleeve to slip the mast into.
Suppose you could get creative and put some plastic plants in the pot.

This works as I am on the 2nd floor, with a rain gutter etc, if you dont have that, the potted plant thing would work, using a long wire for counterpoise.
The main part though is the tunable antenna so you don't have the tuner loss.

Hmmm, wonder how 2 of these would work with one of those hamstick dipole converters....
Nahhh.. too expensive...
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W0FM
Member

Posts: 2052




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« Reply #9 on: June 04, 2001, 06:07:15 PM »

Speaking of back-to-back screwdrivers.  Some years back I wrote to Don Johnson and (now SK) Lew McCoy about an idea I had to put two of Don's screwdriver antennas back-to-back (bottom-to-bottom) as a tunable, rotatable dipole.  Lew and Don both sent me some sketches on counter-rotating gears that would simultaneously move both screwdrivers in and out in even steps, thus keeping both "tuned" legs of the rotatable dipole even.  Their diagrams were too complicated for my mechanical engineering skills, but, I'll bet if someone who knew a worm gear from hiking gear put their mind to it, they could come up with a multi-band, tunable, rotatable dipole for stealth balcony and attic installations.  If anyone has had any luck with this approach, please let me know (I know a good patent attorney...HI!)
73,
Terry, WØFM
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