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eHam Forums => Antenna Restrictions => Topic started by: AD0AE on May 24, 2012, 07:52:38 PM



Title: Thin wire/ "Invisible Antennas"
Post by: AD0AE on May 24, 2012, 07:52:38 PM
Hi All-

A few nights ago I discovered a whole bunch of 22 gauge wire I must have forgotten about.  I thought about possibly using this wire as an a so called "invisible antenna."  I also saw a slick picture in the June issue of QST where a ham took some golf balls, thin wire and was able to hang a wire in a tree.  This seems like a pretty good "easy-up/easy-down" antenna idea. 

With respect to thin gauge wire, what would be a nominal power range to use on a transceiver?  What are some common antenna designs that could work with thin wire?  Is it possible to make a dipole or is an end-fed antenna more common?

Thank you all and 73s,
Steve
AD0AE


Title: RE: Thin wire/ "Invisible Antennas"
Post by: KF7CG on May 25, 2012, 04:12:52 AM
Thin wire antenna for HF generally work well in any configuration where you can maintain the continuity of the wire. Power levels are governed by the same rules as thicker wire antennas.

Because of the better colling of a thin wire antenna as compared a thin wire connecting in a enclosed space, one can generally greatly exceed the nominal power handling of the wire.  Watch out for fire hazards and running too much power where it is hard to physically replace the wire and then go for it.

KF7CG


Title: RE: Thin wire/ "Invisible Antennas"
Post by: K5LXP on May 25, 2012, 04:57:37 PM
what would be a nominal power range to use on a transceiver?

Any wire gauge capable of supporting its own weight as an antenna is more than capable of handling amateur power levels (1500W).


Quote
What are some common antenna designs that could work with thin wire?  Is it possible to make a dipole or is an end-fed antenna more common?

Any kind you want.  If it doesn't break, it will work fine.


Mark K5LXP
Albuquerque, NM


Title: RE: Thin wire/ "Invisible Antennas"
Post by: N4JTE on May 26, 2012, 05:02:45 PM
Making the feed line invisable becomes the real challenge, any size antenna wire will work.
Bob


Title: RE: Thin wire/ "Invisible Antennas"
Post by: WB6BYU on May 26, 2012, 08:18:31 PM
I often use #22 stranded, insulated wire for antennas.  No problems at 100W, and likely will go
much higher.  Magnet wire (solid copper) requires more care as you have to make sure it doesn't
kink, which greatly reduces the strength.  But I've used an 80m dipole made from #26 magnet
wire for 6+ months (including winter winds, but no snow loading) and it still held up.  Don't
try to put a lot of tension on it, however.

A practical lower limit is around #32 or so, because the birds don't notice it in time to avoid it,
so you have a lot more breaks to mend.


What sort of antenna you use depends a lot on your individual circumstances.  For example,
if you can run the coax along the building to a corner, then run wires out from there, the
antenna doesn't have to support the weight of the coax.  Sometimes an end-fed wire is
the best you can do, sometimes you can arrange a loop antenna, or any number of other
options.


Title: RE: Thin wire/ "Invisible Antennas"
Post by: KB8ZF on May 28, 2012, 05:48:45 AM
I am using the #26 gauge insulated wire from the Wireman, I put up a 20 meter dipole on my balcony here where we live in an apartment on the second floor (top floor). The antenna is configured in an upside down U with the end of the legs about 8 feet off the ground, they are hidden in the J channel of the siding going down the building and fed with RG-8X mini coax. I have made contacts to Europe, the Caribbean, all over the US on 20 and have tuned it with a Palstar AT-2K tuner for 40 meters and do well on 40 also Europe and local also. I thought my ham radio days were over here in the apartment but I am shocked at what I have been able to do with the "make-shift" antenna and a hundred watts.


Title: RE: Thin wire/ "Invisible Antennas"
Post by: KH6AQ on May 28, 2012, 08:26:06 AM
The #26 wire from The Wireman is great wire. I've also used #32 wire from Radio ShackTMand it makes an almost invisible antenna. At least until frost sticks to the antenna. It is delicate and you can expect to replace it several times a year.


Title: RE: Thin wire/ "Invisible Antennas"
Post by: WB0U on June 07, 2012, 11:24:40 AM
I put up a cheap and dirty 20 meter dipole using #32 magnet wire and fishing line.

The center is supported by 10 feet of 1 1/2 inch PVC that is tie wrapped to my deck railing.  The open line feed line is inside the PVC tube for a better appearance.   

I expected this antenna wouldn't survive a single winter but it has been up since 2008.

73, Lynn


Title: RE: Thin wire/ "Invisible Antennas"
Post by: WB2WIK on June 07, 2012, 03:15:39 PM
I put up a cheap and dirty 20 meter dipole using #32 magnet wire and fishing line.

The center is supported by 10 feet of 1 1/2 inch PVC that is tie wrapped to my deck railing.  The open line feed line is inside the PVC tube for a better appearance.   

I expected this antenna wouldn't survive a single winter but it has been up since 2008.

73, Lynn

That's pretty cool.

Now, if you expected it to last forever, it would have broken the first day. :P


Title: RE: Thin wire/ "Invisible Antennas"
Post by: VK2WF on June 13, 2012, 02:06:00 AM

To prevent the icing problem - run a bit of DC though it to warm it up.


Title: RE: Thin wire/ "Invisible Antennas"
Post by: W7MJM on June 20, 2012, 12:29:19 AM
I've had good luck with Davis RF "Poly-Stealth" 26 gauge 19 strand insulated copperweld steel wire which I bought at HRO. They sell it in 100 foot rolls. I used about 140 feet to make a full wave 40 meter delta loop. It's flexible, strong enough and doesn't stretch like copper stranded wire of similar gauge. 


Title: RE: Thin wire/ "Invisible Antennas"
Post by: WB6BYU on June 20, 2012, 11:28:31 AM
Quote from: VK2WF

To prevent the icing problem - run a bit of DC though it to warm it up.



That works for a folded dipole or a loop, but it gets a bit tricky with a standard single-wire dipole.
(You'd need to use two wires for each element, fed in parallel for RF and in series for DC.)


Title: RE: Thin wire/ "Invisible Antennas"
Post by: K3AN on July 02, 2012, 08:07:59 AM
The 26 ga. "stealth" wire sold by The Wireman and others is remarkably invisible to non-hams. I ran such a wire across the common parking lot of the townhouse we rented years ago. It was in the open, no more than 25 feet off the ground. No one saw it for almost a year, until a neighbor had a visitor who was a ham. He spotted it immediately but the neighbor never complained. I think most people are tolerant of low-profile "exceptions" to HOA and zoning regulations, but you better not interfere with their home electronic systems! I ran 5 Watts. No problem.

Regardless of what kind of antenna you plan to install, get on very good terms with your neighbors before you put it up. It's hard to turn in a neighbor who's a good friend or golf buddy or one whose wife socializes with your wife, whereas it's easy to turn in the reclusive crank next door.


Title: RE: Thin wire/ "Invisible Antennas"
Post by: HFCRUSR on July 15, 2012, 07:58:46 PM
FWIW I run a fat #12 100' wire that has a jade green coating that blends into blue sky very well making it pretty much disappear in the daytime. It shows on overcast days and at dusk but still not as much because of low contrast..hey-as long as it's clear and daytime, it can be an unobtrusive wire most of the time.


Title: RE: Thin wire/ "Invisible Antennas"
Post by: K0YQ on July 24, 2012, 03:09:24 PM
I used some of the 26 gauge poly-stealth wire as a base fed 70 foot inverted L, about 30 feet vertical and rest horizontal.  Had a bunch of radials buried and used an AH-4 tuner to feed at the base.  Greatly exceeded my expectations and couldn't be seen unless you were right in the yard.  It sure beat having nothin' by a mile!


Title: RE: Thin wire/ "Invisible Antennas"
Post by: AJ3O on July 25, 2012, 02:23:57 PM
I was told by an old ham that the BEST color for wire, guy rope, etc. is a slightly darker shade of purple. Anyone ever try this? Worth a shot with some 18-22 gauge wire, it may be just about invisible...


Title: RE: Thin wire/ "Invisible Antennas"
Post by: KJ6ETL on August 11, 2012, 05:46:41 AM
I have had a 100mtr long dipole made out off thin welding wire running 60ft high over a public green zone. It was impossible to see and worked great :-)


Title: RE: Thin wire/ "Invisible Antennas"
Post by: KD4SBY on October 01, 2012, 07:32:33 AM
I know a Ham who lives in a HOA controlled community, and he uses two end-fed antennas made from Radio Shack 20AWG wire. He uses a buried coax cable that runs to a small tree in the yard, a small bucket underneath by the tree trunk with a balun, and wires running up into the tree to a yard fence no more than 30 feet in the back of his property. That together with a linear + antenna tuner, enables him to push 500 Watts on four bands with excellent results and good receiving capabilities. He claims that he never had the need of spending more than $20 on his antennas to get on the air and make contacts all over the world.(using CW)


Title: RE: Thin wire/ "Invisible Antennas"
Post by: KB2FCV on October 01, 2012, 10:30:18 AM
I had a long wire up with magnet wire and fishing line for a while when I lived in my apartment. It came down once, and when I put it back up I didn't have any magnet wire available and it was hours before CQWW. I put it up with some heavier wire/rope for a weekend but got "discovered" by the apartment people before the weekend was out.. no more antennas allowed. That fishing line/magnet wire antenna was up for quite a while though!


Title: RE: Thin wire/ "Invisible Antennas"
Post by: N0HC on October 13, 2012, 03:21:45 PM
I used magnetic wire for years - I supported it with fishing line through pulley and tensioned by springs..

I ran into an interesting problem - birds could not see it either and ran into it, one morning I woke up to a lot of noise and opened my curtains to see an owl had pulled the whole thing down and was stomping on it on my deck! He did not look happy. I ran a thicker wire after that..

N0HC


Title: RE: Thin wire/ "Invisible Antennas"
Post by: AD0AE on November 04, 2012, 12:57:39 PM
Hi All-

I just wanted to come back to this forum.  First off, thank you all for the many posts I got back about this topic!  As it turned out I have been experimenting with some thin wire antennas from my apartment.  I have at least made a few JT-65 contacts, so that has been successful! 

What has been bothering me a lot is that I have the wire antenna(dipoles or end feds) hugging the side of the building.  I can even attach the wire to a fence across the parking alley.  In both cases, I am getting a TON of noise above 10 MHz.  It mainly sounds like hum.  It is S-9 or so on anything above 10 MHz.  I am also seeing a  dominant 'line' (in the JT65 waterfall) at about 14.077 MHz.  I am wondering what that might be from. 

This result surprised me because I thought getting the antenna outside might modestly reduce the amount of noise I am hearing with indoor antennas, not increase it.  So I am really perplexed why it seems to have gotten worse, not better.

I plan to post onto the RFI forum, because I did notice I have a utility transformer about 25 feet from my operating location and the antenna - could that be hosing me?

Thank you all and 73s
Steve
AD0AE


Title: RE: Thin wire/ "Invisible Antennas"
Post by: TANAKASAN on December 23, 2012, 02:05:08 AM
I also operate invisible antennas due to the neighbor acceptance factor. I'm not sure of the gauge but to make it invisible (and I mean REALLY invisible) I used white insulated wire and painted it at random intervals with gray and sky blue auto paint. The human eye expects to see a continuous line and the change of color against a gray, blue or white sky breaks this up.

The wire has been up for seven or eight years now and I've never received a complaint.

Tanakasan


Title: RE: Thin wire/ "Invisible Antennas"
Post by: N3LCW on December 23, 2012, 11:40:09 AM
Steve,

Give us more of a description of the antenna installation.

Consider using something like the Timewave ANC-4 Noise Phase cancellation filter or the MFJ-1026 equivalent.  They do work against local noise if you use a real noise sense antenna and not the short whip (unless the noise you are trying to filter is in the same room as the rig is).  I've used this filter successfully when I used an attic wire antenna and picked up all sorts of noise from the house.

Andy
N3LCW




Hi All-

I just wanted to come back to this forum.  First off, thank you all for the many posts I got back about this topic!  As it turned out I have been experimenting with some thin wire antennas from my apartment.  I have at least made a few JT-65 contacts, so that has been successful! 

What has been bothering me a lot is that I have the wire antenna(dipoles or end feds) hugging the side of the building.  I can even attach the wire to a fence across the parking alley.  In both cases, I am getting a TON of noise above 10 MHz.  It mainly sounds like hum.  It is S-9 or so on anything above 10 MHz.  I am also seeing a  dominant 'line' (in the JT65 waterfall) at about 14.077 MHz.  I am wondering what that might be from. 

This result surprised me because I thought getting the antenna outside might modestly reduce the amount of noise I am hearing with indoor antennas, not increase it.  So I am really perplexed why it seems to have gotten worse, not better.

I plan to post onto the RFI forum, because I did notice I have a utility transformer about 25 feet from my operating location and the antenna - could that be hosing me?

Thank you all and 73s
Steve
AD0AE


Title: RE: Thin wire/ "Invisible Antennas"
Post by: K0JEG on December 25, 2012, 08:56:33 AM
Steve,

Give us more of a description of the antenna installation.

Consider using something like the Timewave ANC-4 Noise Phase cancellation filter or the MFJ-1026 equivalent.  They do work against local noise if you use a real noise sense antenna and not the short whip (unless the noise you are trying to filter is in the same room as the rig is).  I've used this filter successfully when I used an attic wire antenna and picked up all sorts of noise from the house.

Andy
N3LCW

From the specs of the ANC-4

"Signal Loss, Main Ant. to Radio: 6 dB"

That seems like a lot of loss to me. Have you used one? I have a serious noise problem on 80 Meters and I'd like to see if it would help.


Title: RE: Thin wire/ "Invisible Antennas"
Post by: K9SRV on December 25, 2012, 11:40:33 AM
Ignored this thread first time around, but then purchased a Johnson Matchbox
with a post for a long wire. Sat,, for a camping trip or vacation, do you guys hace and tips as to height, lenghts to avoid, flat vs. sloping etc? I would like to test it here at home where I can put up about 220 feet straight. Also, since its going to the matchbox single wire terminal, I assume I do not have to drive an 8 foot ground ros just for this, although, I "Could" be wrong.  ::)

Any help, input appreciated.
John


Title: RE: Thin wire/ "Invisible Antennas"
Post by: N3LCW on December 25, 2012, 11:42:41 AM
Yes, I use the ANC-4 very successfully.  The 6db figure will vary, but not by more.  It will absolutely pull a signal out buried in local noise.  If you really want to exploit this filter to its fullest you can use it for diversity reception using 2 separate antennas; one dedicated for receive, on all bands.  For example if you are listening to a signal on a frequency with no interference, you can adjust the phase and gain of the two antennas and increase the amplitude of the desired signal.

You really need to read the manual and play with the controls to fully take advantage of what this filter can do.

Timewave recommends a technique of listening on the main antenna and noting the noise level, then switch to the noise sense antenna ( I use my antenna tuner's antenna switch to REMOVE the main antenna from the filter) set the NOISE PHASE fully CCW, and adjust the NOISE GAIN control to match the noise noted on the main antenna.  Switch the main antenna back into the filter (again, using either your antenna tuner or actual antenna switch) and now adjust the NOISE PHASE pot and alternately play with the PHASE RANGE and FREQ RANGE switches until the noise either disappears or is attenuated.  I get better than 35-40db noise nulls, and the signals buried beneath come alive.  

This may sound tedious but if you're stuck in a bad noise situation this works.  I still use it to eliminate the S9 birdies from my cable modem on 30M.  It wipes them out completely.

I hope this helps.

Andy
N3LCW


Steve,

Give us more of a description of the antenna installation.

Consider using something like the Timewave ANC-4 Noise Phase cancellation filter or the MFJ-1026 equivalent.  They do work against local noise if you use a real noise sense antenna and not the short whip (unless the noise you are trying to filter is in the same room as the rig is).  I've used this filter successfully when I used an attic wire antenna and picked up all sorts of noise from the house.

Andy
N3LCW

From the specs of the ANC-4

"Signal Loss, Main Ant. to Radio: 6 dB"

That seems like a lot of loss to me. Have you used one? I have a serious noise problem on 80 Meters and I'd like to see if it would help.


Title: RE: Thin wire/ "Invisible Antennas"
Post by: K0JEG on December 26, 2012, 05:43:43 AM
Yes, I use the ANC-4 very successfully.  The 6db figure will vary, but not by more.  It will absolutely pull a signal out buried in local noise.  If you really want to exploit this filter to its fullest you can use it for diversity reception using 2 separate antennas; one dedicated for receive, on all bands.  For example if you are listening to a signal on a frequency with no interference, you can adjust the phase and gain of the two antennas and increase the amplitude of the desired signal.

You really need to read the manual and play with the controls to fully take advantage of what this filter can do.

Timewave recommends a technique of listening on the main antenna and noting the noise level, then switch to the noise sense antenna ( I use my antenna tuner's antenna switch to REMOVE the main antenna from the filter) set the NOISE PHASE fully CCW, and adjust the NOISE GAIN control to match the noise noted on the main antenna.  Switch the main antenna back into the filter (again, using either your antenna tuner or actual antenna switch) and now adjust the NOISE PHASE pot and alternately play with the PHASE RANGE and FREQ RANGE switches until the noise either disappears or is attenuated.  I get better than 35-40db noise nulls, and the signals buried beneath come alive.  

This may sound tedious but if you're stuck in a bad noise situation this works.  I still use it to eliminate the S9 birdies from my cable modem on 30M.  It wipes them out completely.

I hope this helps.

Andy
N3LCW

Thanks. After reading this thread I checked out reviews of this and other units. I think I might have to give it a try. Most of what I get is broadband hash from overhead power lines, not a single birdie, but it might help a little.


Title: RE: Thin wire/ "Invisible Antennas"
Post by: WB6BYU on December 26, 2012, 11:50:16 AM
Quote from: K9SRV
Ignored this thread first time around, but then purchased a Johnson Matchbox
with a post for a long wire. Sat,, for a camping trip or vacation, do you guys hace and tips as to height, lenghts to avoid, flat vs. sloping etc? I would like to test it here at home where I can put up about 220 feet straight. Also, since its going to the matchbox single wire terminal, I assume I do not have to drive an 8 foot ground ros just for this, although, I "Could" be wrong.  ::)


There are many factors to consider, depending on what bands you want to work, your
available supports, etc.  But here are some general points that I've found from my
experience using long wires, especially for portable operation:

1)  The same RF current flows into both your antenna wire and your ground system.  If you
don't provide an intentional ground system then the outside of your coax, the chassis of
your rig and tuner, and any wiring for headphones, mic, battery cables, etc. will be your
ground system.  That isn't always desirable.  But an 8' ground rod is actually a pretty poor
RF ground (besides being inconvenient for transient operation) so isn't a good approach
anyway.

I've operated without an intentional ground system on several occasions, and sometimes
I've gotten by with it, especially at QRP.  Other times I've had problems with RF feedback
causing quirky symptoms (keyer running amok, panel lights blinking, garbled audio, etc.)

Usually a quarter wave radial wire for each problem band attached to the back of the
tuner will solve such problems by giving the RF somewhere to go.


2)  Using an antenna wire that is a multiple of a half wave makes a high impedance, so the
currents at the feedpoint aren't as large for the same output power.  This makes ground
losses less of a problem.  (The simple radials used in step 1 are not usually sufficient for
this purpose.)  Personally I've had good results with wires around 130' - 135' for 80m
through 10m (at least the pre-WARC bands), though some people don't like using a high
impedance feedpoint.

3)  At a minimum try for 3/8 wavelength of wire on your lowest band.  More is better. 
But I haven't been impressed the times I've used a really long wire, as the pattern tends
to get more directional on the higher bands, and this can be counterproductive.  We tried
a 600' long wire one year on Field Day and it wasn't any better than a dipole (and often
worse.)  Also the MatchBox will do better with higher impedance loads, and may not be
able to match a wire if it is too short.

4)  Height is important for DX on the higher bands.  But if you are mainly interested in
relatively local coverage (within 500 - 1000 miles) on 40m and 80m, then low height
isn't as much of a problem.  In order to get as much of your wire as high as possible, I'd
suggest an inverted-"L" arrangement, where most of the wire is strung horizontally between
two supports, with the remainder serving as a lead-in dropping down to the rig.  But
to a large extent the wire configuration will depend on what supports are available to
you.  A long vertical wire (over about 5/8 wavelength) may not be as effective as a shorter
one, though you can use up to 1 wavelength or so with adequate results.

5) Make sure your MatchBox has been modified to jumper around the receive relay: 
they date from before transceivers were common, and are designed for a 600 ohm output
to a separate receiver when the relay isn't energerized.

6)  The Matchbox does not provide a DC path to ground from the antenna terminal.  I had
one situation where there was enough static charge picked up on the antenna wire that
the capacitors in my tuner were arcing over.  A 100K 10W wirewound resistor from the
antenna to ground (I used a BBQ skewer - it doesn't need a low resistance) will help to
dissipate the charge.  On the other hand, if the high static level is due to nearby
thunderstorm activity, quit operating and disconnect everything.  You aren't going to
be able to create a ground system capable of handling a direct lightning hit in a temporary
portable station.


Probably the best performance I ever got from a long wire was on Field Day from southeast
Alaska with my old Ten-Tec Argonaut.  I had a sloping long wire running from a tall tree
on the shore out over the tide flats to a post I had put up at low tide.  When the tide came
in the sloping wire over salt water gave me an effective low-angle radiator (though I still only
made about 40 contacts.)  Among other things, that requires the right combination of slope
angle and wire length in wavelengths.



Title: RE: Thin wire/ "Invisible Antennas"
Post by: K5TED on December 26, 2012, 12:48:19 PM
I just picked up another SGC auto-coupler and "Stealth Kit". They are truly the Antenna Restricted Ham's friend. The MFJ Noise Canceller is also a good investment. The SG-237 and Stealth Kit can be used to make a nice, compact, 4 or 5 turn wire loop on about a 50" square frame or just suspended wire loop.

To the OP, the SG-237 or other SGC auto-coupler would work well in conjunction with your wire strung around the entire perimeter of your eaves. Put the SGC right at the loop feedpoint.

Keep in mind, though, the radiation pattern of a horizontal wire loop of this sort. Not great for DX, but good out to several hundred miles as it is quite a high angle pattern.

The advantage of the SGC, and it may well be the same with the Icom AH tuners, is that there is no button pushing to tune or clear memories, and no control cable needed. Fully automatic operation. Some other remote tuners will require manual intervention from time to time.

I have an SG-230 mounted outside in a sheltered spot under the eave, driving a 40' horizontal wire. It's powered with a small wall wart transformer plugged into an inexpensive outdoor rated remote control power switch. If I need to reset the SGC to clear memories, I just power cycle it with the remote switch. It does well on 40m - 10m, somewhat useable on 75m and I've actually made a few phone contacts on 160m with it.

As for the MFJ Noise Canceller, I've had mixed luck with it. Certainly, the noise sense antenna needs to be able to see the same signals as does the main antenna or it simply doesn't work. There are also some spacing considerations between sense and main for optimal performance. Be sure to use the hard PTT port, not rely on the RF sensing.


Title: RE: Thin wire/ "Invisible Antennas"
Post by: KH6AQ on December 27, 2012, 12:20:36 PM
Hi All-

I just wanted to come back to this forum.  First off, thank you all for the many posts I got back about this topic!  As it turned out I have been experimenting with some thin wire antennas from my apartment.  I have at least made a few JT-65 contacts, so that has been successful! 

What has been bothering me a lot is that I have the wire antenna(dipoles or end feds) hugging the side of the building.  I can even attach the wire to a fence across the parking alley.  In both cases, I am getting a TON of noise above 10 MHz.  It mainly sounds like hum.  It is S-9 or so on anything above 10 MHz.  I am also seeing a  dominant 'line' (in the JT65 waterfall) at about 14.077 MHz.  I am wondering what that might be from. 

This result surprised me because I thought getting the antenna outside might modestly reduce the amount of noise I am hearing with indoor antennas, not increase it.  So I am really perplexed why it seems to have gotten worse, not better.

I plan to post onto the RFI forum, because I did notice I have a utility transformer about 25 feet from my operating location and the antenna - could that be hosing me?

Thank you all and 73s
Steve
AD0AE

The end fed antenna another half and that half is the AC wiring in the apartment building. Half of your antenna is inside and half is outside.

How about the dipole? If decoupled with a common-mode choke (1:1 current balun) the entire antenna is outside.

How are you feeding the dipole?


Title: RE: Thin wire/ "Invisible Antennas"
Post by: AD0AE on January 01, 2013, 06:40:23 PM
Hi All-

Thank you for the response.  Just to address a few points...

1.  The configuration I was using a few months ago were thin wires that formed an off center dipole.  The wire was #24 (or #22) from radio shack (solid core) that I felt through the screen of my window.  I made effectively an off centered inverted V type dipole.  This was fed through a manual tuner and I tuned it to the usual SWR 1:1 match condition.   This dipole was just on the outside of my building, effectively running along the length of the building.  I tied off the ends by either using some string and tying to a gutter or actually wrapping the wire around the gutter (I know this is probably a horrible idea - but it was meant to be put away rapidly). 

This configuration, while not ideal, still suffered from having a lot of noise.  Some of it I think could be from the apartment.  We have also have a power transformer for the building not more than 50 feet from my operating station.  We may also just be in a noisy environment as well because there are a lot of power poles close by as well.

2. For now, I have had more success using a mag loop antenna indoors.  That has gotten me some modest QSOs, mainly on digital modes.  With it being winter, I am not keen on feeding an antenna outside at the moment.  I am also probably going to be moving fairly soon, so the indoor loops might be "good enough" for now.

3. I have seen some of you guys talk about the mfj 1025,1026, and Timewave ANC-4.  I read a little bit about their operation and it sounds like a pretty neat idea - if you can get it to work.  Would people generally recommend them?  Is there a particular type of noise they are especially well suited for?  I am thinking it might be worth a shot at least.  Given that my antenna for receive and transmit are going to be in the same room, I could see it working potentially.

4. This whole thing raises a new question that I have been wondering about.  Has anyone tried to develop software that could digitally filter out noise?  I am not so much talking about the DSP that is the radio hardware, but more of a software program that would do that?  Kind of like you would feed the audio in and then it would get filtered somehow to clean up the audio?

I only ask because at work I have used Butterworth filter to low pass some of the data that I have been analyzing.  We had high frequency "harmonics" that we wanted to eliminate from our data.  I was just wondering if something similar has been done or could be done?  I'd imagine there are some limitations or issues with these methods.


Title: RE: Thin wire/ "Invisible Antennas"
Post by: VE3FMC on January 04, 2013, 04:05:49 PM
I was in the local Canadian Tire store today and walked past a rack that had MIG welding wire in it. There was aluminum and copper wire. I thought to myself "wow that would make great antenna wire" (The copper) as it is pretty thin. Not sure how strong it would be. Has anyone used that wire for antennas?

It was $10 for two pounds and there has to be a lot of wire on that 2 pound spool.