No space for radials?
A vertical antenna is the easiest of antennas to make and install. You only need one point above the ground from which to let it hang down, or one point on the ground from which to let it stick up in the air. Wire is used for the hanging vertical and self supporting aluminum tubing for the other. With any other antenna material between these two extremes, of flexible wire and hard tubing, I believe that you will be on your own. Of course, I am addressing the home brewer who is going to use 'junk yard' material to fabricate a vertical antenna that will rival the ready made product in performance. Price is not even considered here, because the cost of the shipping alone may exceed the cost of the locally found raw materials used.
In an earlier blog I mentioned that antenna grade aluminun tubing is usually unavailable on the island and nobocy is making any effort to import the tubing that they need. However at the end of the day the verticals are built from materials available locally, and most do not cost anything at all. It is all about resourcesfullness and creativity. Not that the V4 hams have more of that than anyone else. It could be that these hams are just more determined to get on the air quicker than most, and maybe it works to their advantage. It is a law that you would get help when you sought to help yourself. I guess it works in tandem with "seek and you will find".
Most hams may be brought up to think in terms of radials for vertical antennas, and at one time I was there too. Here is what some folks have to say about radials. To be honest I have not read this article word for word, but I guess they are not saying anything out of the usual. I agree that four ground plane radials can work great, especially when you can't get 120 ground radials in place. I have been there so I know. I live on a suburban city lot and even to get 4 elevated radials in place is a major problem, especially when you want them for 40 and 80 meters, and don't even think about 160 meters. Of course you could make them short, coil loaded and tuned, and then grin and bear the reduced gain, etc.
So that is as far as you can get with radials, but if you want to get away from radials, but enjoy the performance that comes with the full compliment of installed radials you only have to convert your antenna into a half wave vertical dipole. I do not have any antenna modeling tools and software to tell you how this will pan out, so I have to rely on the theory and reports from those who have done it before, and my own personal experience. The top and bottom loaded vertical dipole is the practical configuration. There are times when I used to wonder if those expensive software antenna analyser tools are very necessary, but I have developed an interest in the AIM 4170, and by 2010 I may have saved enough pennies from my pension to get one. I must be allergic to the 'tech'.
This morning when I was mountain biking on the hillside it came to me that a trap vertical antenna should be able to benefit from top and bottom loading as it would become a full halfwave in size, and therfore no longer depend on ground radials, or the lack of radials that some hams do not bother to install as per the manufacturer requirements. This loading could call for a bit of experimentation, but that should not be too difficult to achieve. It would be very much like converting to a ground plane first, if the space is available. Top loading may be necessary for 160 and 80 meter operations. I would assume that the smart hams are only using their trap verticals for 40, 80 and 160 meter operation.
The starting point for would be experimenters may be to insulate the antenna from the ground mount post with rubber tubing or whatever. Install a coule ground plane wires for the lowest band, tune and prune them for lowest swr. This is highly possible if a solenoid balun is used at the feedpoint, for without the solenoid balun you may have a hard time to find the self resonant point or see the swr dip. If the ground plane wire is too long for comfort the length can be divided between the bottom and the top of the vertical. This will now test your creativity. When this is working to your satisfaction move up to the next band and tune and prune to your hearts content.
If you find that it works out good for you tell the world about it as someone somewhere may be able to benefit from your experiment. The more hams we have using vetical dipoles, the better it is for our ham communities and DX between them. I have a piece of unknown trap vertical in the backyard. I will try to use that for the experiemntal base for a top and bottom loaded vertical dipiole and see how that compares with my standard. I forgot to mention that for hams with a 1/4 wave ground mounted vertical, they should see a benefit by just raising the vertical above ground, disconnecting the radials and adding the top and bottom loading wires, making it 1/2 wave long from tip to tip. I believe this configuration will turn out to be far quieter than the ground mounted 1/4 wave vertical previously used.
The name of the game is experimenting, and antennas, especially vertical antennas seem to take the cake. I am still looking for a simple cost effective and uncomplicated vertical antenna configuration that can outperform my top and bottom loaded vertical dipole antenna on 40-meters and 80-meters. Maybe in 2010 someboby may invent one.
In an earlier blog I mentioned that antenna grade aluminun tubing is usually unavailable on the island and nobocy is making any effort to import the tubing that they need. However at the end of the day the verticals are built from materials available locally, and most do not cost anything at all. It is all about resourcesfullness and creativity. Not that the V4 hams have more of that than anyone else. It could be that these hams are just more determined to get on the air quicker than most, and maybe it works to their advantage. It is a law that you would get help when you sought to help yourself. I guess it works in tandem with "seek and you will find".
Most hams may be brought up to think in terms of radials for vertical antennas, and at one time I was there too. Here is what some folks have to say about radials. To be honest I have not read this article word for word, but I guess they are not saying anything out of the usual. I agree that four ground plane radials can work great, especially when you can't get 120 ground radials in place. I have been there so I know. I live on a suburban city lot and even to get 4 elevated radials in place is a major problem, especially when you want them for 40 and 80 meters, and don't even think about 160 meters. Of course you could make them short, coil loaded and tuned, and then grin and bear the reduced gain, etc.
So that is as far as you can get with radials, but if you want to get away from radials, but enjoy the performance that comes with the full compliment of installed radials you only have to convert your antenna into a half wave vertical dipole. I do not have any antenna modeling tools and software to tell you how this will pan out, so I have to rely on the theory and reports from those who have done it before, and my own personal experience. The top and bottom loaded vertical dipole is the practical configuration. There are times when I used to wonder if those expensive software antenna analyser tools are very necessary, but I have developed an interest in the AIM 4170, and by 2010 I may have saved enough pennies from my pension to get one. I must be allergic to the 'tech'.
This morning when I was mountain biking on the hillside it came to me that a trap vertical antenna should be able to benefit from top and bottom loading as it would become a full halfwave in size, and therfore no longer depend on ground radials, or the lack of radials that some hams do not bother to install as per the manufacturer requirements. This loading could call for a bit of experimentation, but that should not be too difficult to achieve. It would be very much like converting to a ground plane first, if the space is available. Top loading may be necessary for 160 and 80 meter operations. I would assume that the smart hams are only using their trap verticals for 40, 80 and 160 meter operation.
The starting point for would be experimenters may be to insulate the antenna from the ground mount post with rubber tubing or whatever. Install a coule ground plane wires for the lowest band, tune and prune them for lowest swr. This is highly possible if a solenoid balun is used at the feedpoint, for without the solenoid balun you may have a hard time to find the self resonant point or see the swr dip. If the ground plane wire is too long for comfort the length can be divided between the bottom and the top of the vertical. This will now test your creativity. When this is working to your satisfaction move up to the next band and tune and prune to your hearts content.
If you find that it works out good for you tell the world about it as someone somewhere may be able to benefit from your experiment. The more hams we have using vetical dipoles, the better it is for our ham communities and DX between them. I have a piece of unknown trap vertical in the backyard. I will try to use that for the experiemntal base for a top and bottom loaded vertical dipiole and see how that compares with my standard. I forgot to mention that for hams with a 1/4 wave ground mounted vertical, they should see a benefit by just raising the vertical above ground, disconnecting the radials and adding the top and bottom loading wires, making it 1/2 wave long from tip to tip. I believe this configuration will turn out to be far quieter than the ground mounted 1/4 wave vertical previously used.
The name of the game is experimenting, and antennas, especially vertical antennas seem to take the cake. I am still looking for a simple cost effective and uncomplicated vertical antenna configuration that can outperform my top and bottom loaded vertical dipole antenna on 40-meters and 80-meters. Maybe in 2010 someboby may invent one.
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