Antennas - Take your pick
Now it's time to decide what antennas you're going to use and for what
band. In time many of us have had the chance to play with different
types of aerials from dipoles to large monobanders. Things change and
computers have made life a lot easier for the antenna experimenter.
You can now design your own antennas and put the right specs at the right place. All of my antennas are purposely designed for rtty contesting, they work on the hole band of course but I have tailored the specs to my personal taste exactly where I wanted.
Let's take a look at a few aerials:
Wires:
Wire antennas are practical, inexpensive and effective. I personally find the best material to build wire antennas is #16ga Teflon insulated (black). This will last forever, very strong, small diameter offering less wind resistance, potentially less subject to ice accumulation, capable of withstanding legal limit (key down), very light for those long 80M inverted Vees, a bit expensive but worth every penny.
We find in this category: dipoles, inverted Vees, inverted L, Carolina windom and others.
I use wires where I can't use beams. Before installing the 2 element, for 40M I got as high as I could and that's 72 feet and installed 2 inverted vees with a 90 degree offset. At this height even a Vee has got some (reasonable) punch on 40M. Having 2 crossed sets helped me deal with qrm, in fact I could hear better with the north/south antenna than the east/west one although the latter had bigger gain for W and EU stations.
Verticals:
Vertical antennas are effective for dx work, their radiation angle over the horizon is fairly low. Verticals will work best depending on the quality of ground at your location the best being saltwater. The reason why this happens is because 1/4 wave verticals are only one half antennas the other half being the ground. What you want is a maximum reflection off the ground and back into the vertical radiator. For this reason all verticals need a radial system at their base. The more radials the better. If the vertical is to be elevated from the ground, 2 radials cut to resonance will perform very well as counterpoise system. I use a vertical for my 80M work. Unfortunately they're also noisy antennas and consistently copying dx signals is very challenging. It's therefore wise to have a receiving antenna for this band.
2 elements beams:
2 element beams are surprisingly good antennas if well designed. For the rttyer the good news is that the maximum gain of such array happens in the lower part of the band. I would limit my choice to 3 types:
The yagi will offer a lower front/back ratio and a bit more gain. It's extremely easy to build.
The moxon is in my view the best of the 3 since it will give 0.5 db less gain than the yagi but a higher front/back (up to 35db in the phone section of the band). The moxon can be multibanded but in my view it shines as a monobander and that's the way I use them. Its construction is also fairly easy. Moxons are only 70% the size of yagis.
The hexbeam is a good antenna and its stronger point is that it can be nested for multiband purpose. The construction of the hexbeam antenna requires a bit more work. This is also the smaller of the 3.
You can achieve additional gain from a 2 element yagi by building it 'driven/director' but this will cost you bandwidth. If you're planning to use this antenna exclusively for cw and rtty work then it may be worth the effort.
3 element beams:
When moving from 2 to 3 elements, I would stick to yagis. You can build 3 element moxons but the construction of such array is a bit awkward.
Three element yagis are probably amongst the best performers, a real all around antenna. Not too big, not too heavy, good gain, good front/back, good bandwidth, fairly easy to build, can be designed to 50ohm match. What more do we need? Here's the question: if I had room for them, would I build and install all 3 L monoband yagis for all bands? Answer: I don't know... but I'll definitely settle for that on 40 and 80M :-)
Is there enough difference between a moxon and a 3L yagi on 10-15-20M ? If I had room I would probably add more elements like 5 for 10 and 4 for 15 and 20M.
You know, sometimes we are misled by antenna performance. I've heard and read comments about all kinds of antennas, how this one is a killer, that one is useless and so on. Unless you have them all lined up at the same location and at the same time it's very difficult to judge. In 2001 I was working ZL, JA, VK from my mobile using 100w and my home-brewed vertical on top of the truck (the gain (loss) of such antenna is probably something like -10db at least!!) . Signals with JA were often in the 9+ class. In 2009 I don't recall having worked any JA's from va2up with a 9+ signal and that's for quite sometime. So the killer antenna of yesterday may turn out to be tomorrow's big looser! I bet you in 4 or 5 years as the cycle changes, we'll all have terrific aerials on our towers! When giving out free antenna performance estimations, keep in mind two things: conditions and location (including the height of the antenna).
4 element yagis:
These are serious antennas. You can expect superior gain and performance from such an array. I will talk here about a model in particular the OWA yagi. The Optimized Wideband Antenna as so called by its founder Jim Breakall WA3FET, uses a parasitic element (1st director for yagis) placed very close to the driven element (£ .05l ) to raise the impedance to 50 ohms throughout the band and dramatically increase bandwidth. To the cost of - 0.5 db gain, the several advantages of such design are absolutely terrific. If you haven't had any experience with this antenna, I suggest you try building a small model for 10M. Note that the gauge of the aluminum tubing used for this projects is not meant for extreme conditions. Larger gauge starting at 1 inch and tapered down should be used for long term installations. Aluminum used is 65 thousands of an inch wall, since this is what's available in VE2.
Here's an interesting project for you builders:
You can now design your own antennas and put the right specs at the right place. All of my antennas are purposely designed for rtty contesting, they work on the hole band of course but I have tailored the specs to my personal taste exactly where I wanted.
Let's take a look at a few aerials:
Wires:
Wire antennas are practical, inexpensive and effective. I personally find the best material to build wire antennas is #16ga Teflon insulated (black). This will last forever, very strong, small diameter offering less wind resistance, potentially less subject to ice accumulation, capable of withstanding legal limit (key down), very light for those long 80M inverted Vees, a bit expensive but worth every penny.
We find in this category: dipoles, inverted Vees, inverted L, Carolina windom and others.
I use wires where I can't use beams. Before installing the 2 element, for 40M I got as high as I could and that's 72 feet and installed 2 inverted vees with a 90 degree offset. At this height even a Vee has got some (reasonable) punch on 40M. Having 2 crossed sets helped me deal with qrm, in fact I could hear better with the north/south antenna than the east/west one although the latter had bigger gain for W and EU stations.
Verticals:
Vertical antennas are effective for dx work, their radiation angle over the horizon is fairly low. Verticals will work best depending on the quality of ground at your location the best being saltwater. The reason why this happens is because 1/4 wave verticals are only one half antennas the other half being the ground. What you want is a maximum reflection off the ground and back into the vertical radiator. For this reason all verticals need a radial system at their base. The more radials the better. If the vertical is to be elevated from the ground, 2 radials cut to resonance will perform very well as counterpoise system. I use a vertical for my 80M work. Unfortunately they're also noisy antennas and consistently copying dx signals is very challenging. It's therefore wise to have a receiving antenna for this band.
2 elements beams:
2 element beams are surprisingly good antennas if well designed. For the rttyer the good news is that the maximum gain of such array happens in the lower part of the band. I would limit my choice to 3 types:
- yagi
- moxon
- hexbeam
The yagi will offer a lower front/back ratio and a bit more gain. It's extremely easy to build.
The moxon is in my view the best of the 3 since it will give 0.5 db less gain than the yagi but a higher front/back (up to 35db in the phone section of the band). The moxon can be multibanded but in my view it shines as a monobander and that's the way I use them. Its construction is also fairly easy. Moxons are only 70% the size of yagis.
The hexbeam is a good antenna and its stronger point is that it can be nested for multiband purpose. The construction of the hexbeam antenna requires a bit more work. This is also the smaller of the 3.
You can achieve additional gain from a 2 element yagi by building it 'driven/director' but this will cost you bandwidth. If you're planning to use this antenna exclusively for cw and rtty work then it may be worth the effort.
3 element beams:
When moving from 2 to 3 elements, I would stick to yagis. You can build 3 element moxons but the construction of such array is a bit awkward.
Three element yagis are probably amongst the best performers, a real all around antenna. Not too big, not too heavy, good gain, good front/back, good bandwidth, fairly easy to build, can be designed to 50ohm match. What more do we need? Here's the question: if I had room for them, would I build and install all 3 L monoband yagis for all bands? Answer: I don't know... but I'll definitely settle for that on 40 and 80M :-)
Is there enough difference between a moxon and a 3L yagi on 10-15-20M ? If I had room I would probably add more elements like 5 for 10 and 4 for 15 and 20M.
You know, sometimes we are misled by antenna performance. I've heard and read comments about all kinds of antennas, how this one is a killer, that one is useless and so on. Unless you have them all lined up at the same location and at the same time it's very difficult to judge. In 2001 I was working ZL, JA, VK from my mobile using 100w and my home-brewed vertical on top of the truck (the gain (loss) of such antenna is probably something like -10db at least!!) . Signals with JA were often in the 9+ class. In 2009 I don't recall having worked any JA's from va2up with a 9+ signal and that's for quite sometime. So the killer antenna of yesterday may turn out to be tomorrow's big looser! I bet you in 4 or 5 years as the cycle changes, we'll all have terrific aerials on our towers! When giving out free antenna performance estimations, keep in mind two things: conditions and location (including the height of the antenna).
4 element yagis:
These are serious antennas. You can expect superior gain and performance from such an array. I will talk here about a model in particular the OWA yagi. The Optimized Wideband Antenna as so called by its founder Jim Breakall WA3FET, uses a parasitic element (1st director for yagis) placed very close to the driven element (£ .05l ) to raise the impedance to 50 ohms throughout the band and dramatically increase bandwidth. To the cost of - 0.5 db gain, the several advantages of such design are absolutely terrific. If you haven't had any experience with this antenna, I suggest you try building a small model for 10M. Note that the gauge of the aluminum tubing used for this projects is not meant for extreme conditions. Larger gauge starting at 1 inch and tapered down should be used for long term installations. Aluminum used is 65 thousands of an inch wall, since this is what's available in VE2.
Here's an interesting project for you builders:
|
|
|
|
|
I'm sure you'll love this antenna. This design has elements isolated from the boom of course. If you are not familiar with antenna software and need more info about this project you're welcome to drop me an e-mail. |
This concludes the chapter on antennas although so much more could be said. I have purposely omitted quads since for our climate in VE2 they may present some mechanical problems especially during ice storms, I'm therefore not too comfortable using them although quads are extremely good antennas.