Planning a Long Wire

[AK4BM]

I am planning on a longwire for my base antenna, but am not sure what length to use.

I can run about 120 feet in an L shape. I was planning on using 14 gauge stranded, insulated wire.

Any thoughts? I'm new to HF, so any advice would be great.

Thanks!!

Robbie
KJ4JFT

[AK4BM]

I am planning on running an MFJ949D to tune the radio. In addition, I'm going to run a dedicated ground rod to help with the counterpoise.

Robbie

[WA7OET]

I am planning on a longwire for my base antenna, but am not sure what length to use.


A long wire is by definition a minimum of one wavelength long. You can feed it in the center with open wire line and a tuner which will allow you to use it on all bands or feed it one quarter wave from one end with coax, which will make it a single band affair. Or, you could feed it at one end with open wire line for all bands. Or you could feed it at one quarter wave from the end with open wire line for all band use.

The patterns will change depending on where you feed it.

Dont confuse a long wire with a random wire.

Good luck.

[W6PU]

I am planning on a longwire for my base antenna, but am not sure what length to use.

I can run about 120 feet in an L shape. I was planning on using 14 gauge stranded, insulated wire.

Any thoughts? I'm new to HF, so any advice would be great.

Thanks!!

Robbie
KJ4JFT


120Ft. is OK, but I would make it a total of 135 feet long,and use as a single wire end fed along with a good antenna tuner of the appropriate power handling capability. This antenna will be 1/2 W. long on 3.5Mhz, and 1/4 wave on 160 where you will work it against a radial/s or even a cold water pipe ground.

One draw back if you intend to run much more than 100W input, is that you might get some RF (bite) in the shack, but try it first, as there are effective ways to deal with the latter( which we can address here on QRZ) if it should be a problem!

73
Bob W6PU

[AK4BM]

I am thinking more of a random wire with the tuner.

In doing some research, I have found that about 74 feet should work pretty well. I only have access to 80-10 meter, those are the limits of my radio.

I could also run more than one length wire with a swtich....I hadn't really thought about that side of it.

Robbie

[W4CBJ]

Here we go again ! Simply put up a wire, strong enough (actual wire size is irrelevant). insulated or not, solid or stranded, Copper or steel (galvanized for corrosive atmospheres), end-fed with tuner, with adequate (RF) ground and TRY it. In almost any configuration, the thing will work fine. Multi-band non-harmonically related configurations CAN be tricky...at certain frequencies. Quit trying to 'DESIGN' a simple wire antenna and put one up. You MAY be surprised how well it will work. You don't need coax or balanced lines or baluns. I have done this many times and in each case...it worked OK. If it DOESN'T (rarely) try something else. from the "best advice department" ....
73 Joe W4CBJ

[M0DSZ]

Here we go again ! Simply put up a wire, strong enough (actual wire size is irrelevant). insulated or not, solid or stranded, Copper or steel (galvanized for corrosive atmospheres), end-fed with tuner, with adequate (RF) ground and TRY it. In almost any configuration, the thing will work fine. Multi-band non-harmonically related configurations CAN be tricky...at certain frequencies. Quit trying to 'DESIGN' a simple wire antenna and put one up. You MAY be surprised how well it will work. You don't need coax or balanced lines or baluns. I have done this many times and in each case...it worked OK. If it DOESN'T (rarely) try something else. from the "best advice department" ....
73 Joe W4CBJ
Absolutely! I put up a 200' wire over 5 years ago, made an L-match (50ohms input) and it tunes up on any amateur frequency. Beware though, it has already been mentioned that under certain conditions you may have a high voltage at the tuner. This is when my L-match becomes a SERIES-match.

[AI3V]

Robbie,

The random wire fed against a ground will work.

HOWEVER

You will need a LOT of buried wire to equal the performance of a simple, 1/2 wave (at the lowest frequency you are interested in), ladder line fed, doublet .

In theory, you will need 120 x 1/4 wave radials for the ground system. :eek:With perhaps 16 needed for "Good" results.

In your situation, I would install the wire you have as a doublet. WAY more "Bang for the buck"

Don't worry about baluns, special length lines, etc. Just run the ladder line straight from the tuner to the antenna.

And don't worry about radiation patterns, It will not be anything approaching the theory books.:D

Rege

Edit: The problem with a random wire, using the house wiring/water pipes as a counterpoise, is that you have brought 1/2 of the antenna (and the associated RFI issues) into your house.

[N8CPA]

I am planning on running an MFJ949D to tune the radio. In addition, I'm going to run a dedicated ground rod to help with the counterpoise.

Robbie

Tuners don't tune anything. They only match a XCVR to a feedline. All parasitic conditions along the feedline are unchanged between the tuner and the antenna. So make sure your tuner and XCVR are well grounded, also--lest you feel the bite.

[W7LPN]

The aluminum electric fence wire is of much higher quality today than it was years ago. It actually works very well. I have one up above my home, and keep a roll in my camping supplies with an old fishing pole & 1 oz fishing weight to get it up in the trees. It was a lot cheaper than copper as well. As far as length, I put as long a length as possible, then trimmed until it would tune on all the bands I wanted. I believe it's about 60ft upward to the bend in the "L", then about 16ft downtilt.

[W7LPN]

Robbie,

The random wire fed against a ground will work.

HOWEVER

You will need a LOT of buried wire to equal the performance of a simple, 1/2 wave (at the lowest frequency you are interested in), ladder line fed, doublet .

In theory, you will need 120 x 1/4 wave radials for the ground system. :eek:With perhaps 16 needed for "Good" results.
:D

Rege

Edit: The problem with a random wire, using the house wiring/water pipes as a counterpoise, is that you have brought 1/2 of the antenna (and the associated RFI issues) into your house.

In reality, slightly longer than 1/4 wave wire mounted to a mechanically grounded (1/2" copper ground rod) antenna coupler performs very well, even w/o radials, because of the superior matching ability of a coupler vs a tuner.
Yes, I understand math doesn't lie, but the proof is in the results. :cool:

[W4CBJ]

Used to have two (2) boats. First was a 34 foot house boat, second was a 27 foot Catalina Diesel motorsailer. Used amateur radio onboard with fantastic results. Secret was the SALTWATER ground. Good RF ground makes the difference.
M0DSZ/Hugh.....thanks for your comments. 73 Joe W4CBJ

[AI3V]

In reality, slightly longer than 1/4 wave wire mounted to a mechanically grounded (1/2" copper ground rod) antenna coupler performs very well, even w/o radials, because of the superior matching ability of a coupler vs a tuner.
Yes, I understand math doesn't lie, but the proof is in the results. :cool:


Incredibly bad advice.

We should try and HELP the guy, not have him build a dummyload/rfi generator for a antenna.

Rege

[N8CPA]

Incredibly bad advice.

We should try and HELP the guy, not have him build a dummyload/rfi generator for a antenna.

Rege

Not necessarily bad, if 'coupler' means an LC network at the feedpoint of the antenna, the remote end of the feedline; as opposed to a tuner, an LC network sitting on a desk, merely matching the XCVR to the feedline.

[W7LPN]

Incredibly bad advice.

We should try and HELP the guy, not have him build a dummyload/rfi generator for a antenna.

Rege

Opinions vary. As I Said, If it works well, it works well. Some things work well even if the engineers don't like it. :eek:

[W7LPN]

Not necessarily bad, if 'coupler' means an LC network at the feedpoint of the antenna, the remote end of the feedline; as opposed to a tuner, an LC network sitting on a desk, merely matching the XCVR to the feedline.

A feed point coupler is far superior than a tuner, in my personal experience. I didn't just read that, I proved it. :rolleyes:

http://www.hamuniverse.com/fourdollarspecialw1gfh.html

another good design

[K4SAV]

If you take a 40 meter vertical and add a good radial system (say about 30 quarter wavelength radials) the gain should be about -1 dBi. If you take that vertical and only use a single ground rod plus a very good choke on the feedline (which you will need) the gain should go to about -4.7 dBi. That's a 3.7 dB difference. That's only a little over half an S unit on a calibrated S meter, so yes you should be able to make some contacts on it. It's also true that in this example the antenna without radials only radiates about 34% as much as the one with radials. One antenna isn't going to "kill" the other, but the one with radials will work a lot of weak stations which the radial-less one will not.

The worst part of any single-ended antenna is trying to get rid of the common mode currents on the feedline (if you have a feedline). These cause RFI to everything in the shack. It also works in two directions. All the electronics and motors in the house create a lot of ground noise. These travel up the feedline (if you have one) as common mode currents and into the antenna. You will hear them. If you don't have a feedline and just have a single wire attached to a tuner, then your antenna is connected directly to the noise source (house AC ground) which is a worst case situation.

Another bad thing about a single ended wire connected to a tuner in the shack is that it puts YOU holding onto one leg of the antenna. The same amount of current that goes into the antenna also goes into the ground wire. It's very difficult to get a good RF ground inside a shack. Even if you could, it puts YOU at the highest field intensity point of the antenna (for a quarter wavelength or less antenna). If you do the RF safety survey (which we are required to do) then you probably won't pass.

Jerry, K4SAV