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Author Topic: Austin Suburban Antenna?  (Read 665 times)

KB1OHB

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Austin Suburban Antenna?
« on: December 26, 2020, 09:06:03 AM »

So, I live in a condo in a dense urban area. No antennas allowed. I am also worried about lightning. The condo is a townhouse, with a flat rubber roof. Did I also mention that it is on the water, so very high winds are also an issue? I have been looking for a stealth antenna to put on my roof, because I can’t hit my favorite club repeater.

BTW, are ventennas still made? The website is still up, but has anyone bought one recently? Putting something over my vent stack would be a great solution.

Anyway, also considering the Austin Suburban. Has anyone mounted this horizontally? Our roof has a decoration railing and I could easily hide it if I were able to mount it horizontally.

Please excuse my ignorance- getting back on the air after years off and can’t believe how much I have forgotten!
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KG4RUL

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Re: Austin Suburban Antenna?
« Reply #1 on: December 26, 2020, 10:00:28 AM »

Mounting the Austin or any other vertical antenna horizontally will result in about 20dB of signal loss - not what you are trying to achieve.  Have you considered making an antenna, on a window facing the repeater in question, out of copper foil tape?

- Get a roll of 1/2" wide, adhesive backed, copper foil tape available from Amazon for about $8.00.

- You will need 50 ohm RG-58 coax cable with a connector that will fit on your handheld and is long enough to reach from the radio to the antenna.

- Obtain some ferrite toroid "donuts" that can slide over the RG-58 cable. 10 FT50-43 Ferrite Toroid Cores from Amazon are $9.00. The toroids are used to "block" any reflected RF signal back down the outside of the coax and back to the radio. This is because the antenna in nominally 72 ohm and is not an exact match to the 50 ohm cable.

- Get a hold of some shrink tubing that will easily fit over the toroids on the RG-58

- Slide 3 - 4 toroid donuts over the coax along with the piece of shrink tubing and push far away from the loose end of the coax for some working room. Do not shrink the tubing yet.

- Strip about 1.5" of the center conductor and 1.5" of braid from one end, making sure both are separated and not grounding to each other. Tin both conductors with solder.

- Slide the toroid donuts back close to the stripped end of the coax, 1/8" away from the cut edge of the outside insulation. Shrink the tube over the toroids to lock in place.  Don't overheat the coax or you will melt it!

-  Cut two lengths of copper foil pole 22" in length.  When you start "tuning" the antenna, you will be shortening (cutting) each pole until you find the best match.

- Tin both both lengths of copper foil. at one end, then solder each tinned conductor  of the coaxial cable to each piece of copper foil.

- The legs of copper foil should be placed from 1" to 2" apart.  A convenient way to tune the antenna is to temporarily tape it onto a  a 5' long piece of wood or pvc pipe with blue painter's tape. This way you can find best length of each leg, to obtain the best SWR, before mounting on the window.

- Transfer the completed antenna, to the window taking care to route the coax at right angles for several feet.
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K1KIM

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Re: Austin Suburban Antenna?
« Reply #2 on: December 26, 2020, 02:31:10 PM »

Go to Ed Fong's webpage and order the roll-up that you put in PVC.

He has the 2M and the dual band.

I have mine in the house and on 1W hit the local repeater 20 miles away.

Good antenna and a portion of the sales go to the students at the university where he teaches.
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So Many Toys.......So Little Time!

W9IQ

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Re: Austin Suburban Antenna?
« Reply #3 on: December 26, 2020, 02:55:31 PM »

Obtain some ferrite toroid "donuts" that can slide over the RG-58 cable. 10 FT50-43 Ferrite Toroid Cores from Amazon are $9.00. The toroids are used to "block" any reflected RF signal back down the outside of the coax and back to the radio. This is because the antenna in nominally 72 ohm and is not an exact match to the 50 ohm cable.

The reason for common mode current has nothing to do with the 72 ohm to 50 ohm mismatch. It is because the outside shield of any coax acts like a third wire connected to the antenna. The degree of common mode current depends on the length of the coax, its routing and any grounding but there will always be some undesirable common mode current.

Using a few ferrite beads may choke off the current if it isn't too severe. On HF frequencies, type 31 material will be superior to type 43. Using one larger toroid with the correct number of turns will provide superior choking compared to a large number of beads. It will be more effective, cost less and weigh less.

If you are in an urban or suburban environment a second choke located just before the coax enters the shack will help keep RFI out of the receiver.

- Glenn W9IQ
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- Glenn W9IQ

God runs electromagnetics on Monday, Wednesday and Friday by the wave theory and the devil runs it on Tuesday, Thursday and Saturday by the Quantum theory.

KF5LJW

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Re: Austin Suburban Antenna?
« Reply #4 on: December 26, 2020, 04:00:02 PM »

Here you go. Just a SO-259 connector and 14 AWG scrap wire.

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W1BR

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Re: Austin Suburban Antenna?
« Reply #5 on: January 02, 2021, 12:27:28 PM »

Richard Austin is a silent key
.
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NA4IT

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Re: Austin Suburban Antenna?
« Reply #6 on: January 02, 2021, 01:04:52 PM »

Here you go. Just a SO-259 connector and 14 AWG scrap wire.



Since I designed the antenna mentioned, here is the full webpage with instructions.
https://www.qsl.net/na4it/dbgp.html
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WB6BYU

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Re: Austin Suburban Antenna?
« Reply #7 on: January 03, 2021, 01:02:07 PM »

Quote from: KB1OHB

Putting something over my vent stack would be a great solution.



What band do you need for the repeater?

What are your vent pipes made of?


Making a vent pipe antenna is fairly simple, especially if your vents
are black ABS pipe sticking out above the roof.  A quarter wave ground
plane for 2m is only 18 - 20 inches tall, and you can get a 2 foot piece
of ABS pipe and use it to extend your vent, then put whatever antenna
you want inside.

If you run your coax up the vent pipe, make sure you have some sort
of a trap at the house end so you don't get sewer gasses in the house.

You can also make a dummy vent pipe, using the flashing fittings that
seal to the roof (and perhaps a few extra shingles to hide the base)
and stick it anywhere on the roof you want - rarely does anybody
actually loop up at the roof, and black vent pipes don't attract attention.
If you want to get creative, you can get aluminum stove pipe
sections and make a fat vertical, even with a top piece on it.  Take
a stroll through the plumbing and roofing sections of your local
Home Improvement store and see what they carry.  Our roof has
sheet metal covers that fit on the roof, with a hole for the pipe
to come out, and that would make a convenient ground plane
(depending on the band you want to use).  If you have sewer
gasses venting up the pipe, then just tape a wire to the outside
of it rather than putting it inside.

There are designs for (mostly) horizontal antennas that are still
vertically polarized.  For example, a loop about 14.5 inches high
and 29 inches long, mounted in a vertical plane, will give vertical
polarization and a 50 ohm impedance when fed in the middle of
one side.  You can go even shorter (and wider) than that, but it
requires a bit more fussing to get a good match.

If your window faces towards the repeater, you can try just
hanging a ground plane on the inside of it with a suction cup
(often sold for stringing Christmas lights) and using just two
radials so it hangs flat against the glass, which can be behind
a curtain.  (This might not work as well with some types of
passivated glass designed to reduce heating from the sun.)

You'll also be surprised how invisible a black quarter wave
whip is when mounted on a balcony, especially when disguised
as part of a flower pot stand, umbrella, or other permitted item.

ONAIR

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Re: Austin Suburban Antenna?
« Reply #8 on: January 03, 2021, 04:05:29 PM »

Ever consider using a small beam indoors?  I use the ELK portable 2m/440 beam inside hotel rooms when I travel, with excellent results! ;)    www.ElkAntennas.com
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