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1-10 of 13 messages
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Best Homebrew Multiband Antenna?
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by N1RGL on June 3, 2009
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Fellow hams, I just picked up a Yaesu FT-450 radio and a LDG AT-100Pro tuner. Now it's time to build the antenna and I don't want to screw it up. :-)
1. Just wondering what your opinion is on the best homebrew multiband HF antenna. I like the multiband fan dipole described here: http://www.hamuniverse.com/multidipole.html.
2. Is it your opinion that it is better to use coax or feedline?
3. Do I need a balun? If so, should I buy one or make the one described here: http://www.hamuniverse.com/balun.html
4. Also, your thoughts on materials, pricing, and suppliers would be appreciated.
I've only just recently gotten back into ham radio after 20 years. There are some things I remember and a lot I have forgotten. Therefore, your opinions and specific reasons for them are appreciated. If you would like to contact me off-forum, you can do so at hippie dot hideaway at gmail dot com. Thank you in advance for your help.
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RE: Best Homebrew Multiband Antenna?
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by N1RGL on June 3, 2009
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For point #2, I meant to write "...coax or ladderline?
I would like to add:
5. What are some hints/tricks/tips that you have found helpful in your antenna building experience?
Thank you.
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RE: Best Homebrew Multiband Antenna?
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by WA7NCL on June 3, 2009
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Decide what bands to use
Build a dipole that is 1/2 wave on the lowest band. Feed it with Window Line (not TV twin lead). Add a 1:1 balun to output of the AT-100. You are good to go. You might have to adjust the length of the window line if there are some bands you can't tune easily. You can run a short length of low loss coax to the balun if you don't want to run ladder line thru walls or windows.
Personally I just run the ladder line in my vertical slider window (its vinyl) and close the window on it. There is enough slop in the window that I can close and lock it. The window line is made of copper weld so it is very tough. The plastic window is insulating.
If you want more plug and play, get a commercial trap dipole and feed the ant with low loss coax.
Stay away from G5RVs and OCF windoms etc. You will just be posting again looking for solutions to "RF in the Shack" or "how do I ground my rig". Just don't go there. They are not the magic "all band" solution.
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RE: Best Homebrew Multiband Antenna?
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by AA4PB on June 3, 2009
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There wouldn't be any reason to use ladder line to feed a fan dipole because it presents a pretty good match to 50 ohm coax on all bands.
Ladder line is used for a "doublet" antenna because the single antenna wire presents a wide range of impedances, depending on the band. Coax would have too much mismatch loss on some bands.
Provided you have a tuner and can manage to route the ladder line into the house, the doublet (minimum of 1/2 wavelength on the lowest operating frequency) is the easiest to get working properly.
The fan dipole has the advantage that it can be fed directly with coax and doesn't require a tuner. The trade-off is that its a lot more trouble to get to to resonate on each of the bands.
Another option that many people seem to forget these days is the trapped dipole. It has resonant traps (like a tri-band yagi) that divides the element into the proper length for each band. It also can be fed with coax and doesn't require a tuner.
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RE: Best Homebrew Multiband Antenna?
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by WD4HXG on June 3, 2009
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1. Just wondering what your opinion is on the best homebrew multiband HF antenna. I like the multiband fan dipole described here: http://www.hamuniverse.com/multidipole.html.
This type of antenna is pretty straight forward for three bands. The 4th band was problematic for me but then I was in a bit of a hurry and not thrilled about the up and down for cut and try.
2. Is it your opinion that it is better to use coax or feedline?
If the antenna exhibits less than a 2.5:1 VSWR at the frequencies you will use then coax is fine. If the VSWR climbs above 5:1 I insist on using ladder line or open wire feeders.
Open wire feeders shine in antenna systems were the antenna feedpoint impedance is way off 50 or 75 ohms incurring high losses in coax feeds. Open wire feeders will beat the coax hands down due to loss being much lower than coax.
3. Do I need a balun?
Yes and no. You are not likely to notice any difference in the performance in QSO's with or without a balun. The thought on baluns is that if the dipole is not symmetrical either physically or due to a nearby metallic object then the imbalance can create oddball currents on the coax shield. My first dipoles did not use baluns and they provided many hours of pleasure. If you have more of the purist leanings then you may want to use one as when placed at the antenna feedpoint-feedline junction you minimize any stray currents running along the coax.
If so, should I buy one or make the one described here: http://www.hamuniverse.com/balun.html
It depends. If you have not built anything before then it may be best to go with a commercial unit. Once you have a known good working antenna and want to try building a project then the balun is a good place to have some fun.
I personally steer away from ferrite core baluns unless I know the point they operate in the antenna system will not see a VSWR above 2.5:1 and there is no chance of exceeding the rated power spec. Ferrite core baluns will heat up rapidly when operated into a high VSWR at even 100 watts. For a good read on baluns chase down a copy of Jerry Sevick's book on Baluns titled "Understanding, Building, and Using Baluns and Ununs".
4. Also, your thoughts on materials, pricing, and suppliers would be appreciated.
I've only just recently gotten back into ham radio after 20 years. There are some things I remember and a lot I have forgotten. Therefore, your opinions and specific reasons for them are appreciated. If you would like to contact me off-forum, you can do so at hippie dot hideaway at gmail dot com. Thank you in advance for your help.
Vendor prices are always high. After all they are mostly in business to earn a profit. It is fairly straight forward to chase down pricing on coax, open wire feeders, baluns, antennae, aluminum tubing etc on the internet.
The antenna I use now is a dipole cut to resonance on 80 meters, fed directly with ladder line, connected to a Johnson Matchbox antenna tuner. I have no balun and signal reports are more often then not excellent on any domestic QSO I can hear. The Johnson Matchbox allows tuning the antenna on 40, 20, 15 and 10 meters. 40 and 20 work well but my schedule prevents me from hitting 15 and 10 during optimum times so I can't provide a personal perspective on the performance there. Also realize I HAVE NOT conducted field strength measurements to evaluate the antenna efficiency or pattern. The current setup meets my expectations and since I do not possess the test gear and am not inclined to invest in it while the antenna provides me usable performance I will plod along and enjoy my ignornace. :-)
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RE: Best Homebrew Multiband Antenna?
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by W4HV on June 4, 2009
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The best homebrew antenna will always depend on several factors.
1. Budget
2. Xyl factor (Can I get by with this)
3. What are my operating habits?
4. What is my availible space for this antenna?
5. Do I have restrictions that limit me?
6. Can I do it safely?
7. How good is this thing going to perform?
I placed them in basic order of importance because all are real considerations. All that being said a multiband dipole (sometimes called a fan) is an easy and inexpensive soultion. Just a tip here, don't use regular wire. Try using ladderline!..It can be cut to provide 2 wires at a consistent spacing and can be made to operate more than 3 bands very well! (The old NOW YOUR TALKING manual put out for novice and technician class featured this type of antenna!) One can add a second piece of ladder line to add two more bands and have the 5 major bands covered. If you use a tuner on this it will also work the warc bands. Its just a suggestion for a new ham and its cheap and easy to build. Wrap a choke balun around some 1 1/2 inch pvc (use about 22 feet)with rg-8x coax and put this at the feed point. It works great to stop feed line radiation and again its cheap and easy to make. If you are creative you can even use it as your center insulator! One of the things that is magic in ham radio is making your own and seeing it work. If we shoot for the best the firsttime we set ourself up for disappointments in each project we build after that because we already have the best. The main point is to have fun! NOW THAT IS BEST ANTENNA! ONE I MADE AND HAD FUN WITH! Even though I run an antenna company and have good antennae, the weekend often finds me with wire, cutters, solder, pipe, and such in hand having fun!
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RE: Best Homebrew Multiband Antenna?
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by WB6BYU on June 4, 2009
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Any time someone asks, "What is the best [antenna / rig /
etc.]" that should be a warning sign, because there usually
is NO one "best" item. Everything is a matter of trade-offs
and preferences, and without examining what is important
to you, and what your limitations are, it is difficult for
us to make good recommendations.
For example, one could say that the best homebrew multiband
antenna is a huge log-periodic array covering 3 to 30 MHz
on a 200' rotating tower. Yes, that probably would be a
good antenna, and could be built by someone with the
required skills and resources (financial and otherwise).
But it would be impractical for most hams. Similarly an
adjustable mobile whip may not be very efficient, but it
may be the best you can manage if you are operating from
a seagoing kayak. (And it may give spectacular results
in that specific situation.)
I've used a number of simple multi-band antennas: long
wires, loops, multiple dipoles with a common feedpoint,
vee beams, etc. They all work. Some may be more suited
to your specific available supports than others. In fact,
the actual performance differences among them aren't
that significant (other than differences in the radiation
patterns that may favor some directions over others.)
I happen to be fond of horizontal loops when they fit the
available space, fed either with balanced line or with
coax to a 4 : 1 balun (if the length is adjusted to
resonance.) A doublet gives you simple multi-band
capability with a single antenna, as long as you are
willing to readjust the tuner when you change bands.
Multiple dipoles on a common feedpoint require more
adjustment initially, but then bandchanging is much
easier. Which is more important for your operating style?
Multiple dipoles on a common feedpoint don't have to be
difficult to tune: I have a set of dipoles that I've
used for portable operation for the past 30 years without
any adjustments or using a tuner in spite of the many
different supports and configurations I've tried. (Tying
each wire off to a different anchor point minimizes the
tuning interaction between wires.)
Or try a TRUE fan dipole: 5 wires each 40' long on each
side of a 4 : 1 balun and spread into a fan will cover
40 - 10m continuous with a reasonably low SWR (well
within the matching range of a built-in autotuner, or
even the output network of most tube rigs.)
If you want a directional multiband wire antenna then a
long wire array such as a rhombic or vee beam might be
a good choice, or a fixed wire log periodic antenna.
Again, this all depends on what is most important to you
based on your operating preferences.
But probably the best suggestion is simply to pick a
reasonably good antenna design and install it using
halyards and pulleys so you can easily take it down and
try something else. (Even better if you can put up more
than one antenna at a time and compare them.) That
allows you to try out different types of antennas to see
which ones you like best.
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RE: Best Homebrew Multiband Antenna?
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by W7ETA on June 4, 2009
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Well, its summer time.
Maybe a simple inverted Vee for 20 meters with 17 meters at the same feed point?
My first antenna was a trap 40/80 meter inverted Vee that also loaded on 15 meters. I used a CB antenna for 10 meters. I wasn't allowed on 20 meters.
I had a lot of FUN.
I made a 40 meter ground plane using wire and an SO239 that I pulled into a pine tree--had a lot of FUN with that in the winter.
When I was allowed onto 20 meters, I made a ground plane with wire and an SO239 (again) pulled into an old oak tree. I added a 15 meter vertical section, drilled 4 more holes into the SO239 and added 15 meter radials--had even more FUN.
The problem with home made antennas is that once you start having FUN with one, you wanna make MORE of them for more FUN.
73
Bob
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RE: Best Homebrew Multiband Antenna?
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by TANAKASAN on June 6, 2009
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A dipole with 21 feet on each leg. Either feed with ladder line to an ATU in the shack or (better) wire the dipole directly to a remote ATU and run 50 ohm coax to your rig.
For better results on 80 metres and below use 42 feet on each leg if you have the space.
Tanakasan
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RE: Best Homebrew Multiband Antenna?
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by K5YF on June 8, 2009
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All good suggestions and advice.
There have been few, and I mean count them on one hand, advances in antenna technology in the past 20 years. So you haven't missed anything there.
I am partial to home-brew wire antennas myself so these suggestions are all of that type.
If at all possible (lots of emphasis) make at least 2 antennas and 3 would be better.
Make at least one halfwave something. The fan dipole certainly is good and mine work well at 35ft. I can cover the U.S. most days and easily into Europe with it firing East-West from here in VA. Feed it with whatever you like... with a voltage balun or a current balun... its going to perform about the same... which is to say it performs well.... (I have more than one, they are directional after all) but feeding it with ladder line "can" (qualifier there) help it to operate more efficiently and thus be better on receive.
Make a vertical. You can ground mount it, put 2 or more nice long radials under it (more is better up to a point -- ask if you want more info here or search the forums) and feed it directly with the tuner. Get it 100ft or more from the house and its even better. (just lay the radials in the grass, staple them down, and let nature hide them for you). This one is omni-directional, has low-angle radiation for some sweet dx. Elevate it to 12ft or higher, with the radials elevated too of course, and it will really perform nice. DX heaven and multibanded too... with a tuner. Lots of good info here on the forums and all over the net to help with this... and recently pictures in the article section.
Last but not least... something to throw RF straight up. I prefer a loop for this duty, 10ft to 12ft is plenty high off the ground, circle a half acre lot or more, feed it with ladder line, and your smoking the locals with 50w if they have an NVIS too. (NVIS is how the U.S. military does local HF comms) If you happen to have a chain-link or cyclone fence surrounding your property put it above that on some 2x2's and you are golden.
One fixed antenna really can't do it all. I have 4 antennas at my qth and will have 2 more when the tower goes up :)
Be safe, be well, be happy!
73,
-Brandon
-K5YF
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