There are very many different discone antennas from which to choose. Selecting the right discone to buy is not always as easy as it seems.
Different discones have different shapes and sizes and some have an additional vertical element that sits above the main antenna. What is best and what should the selection criteria be to ensure the best discone is bought?
Discones are primarily made either for the scanner market, or for commercial or military monitoring. This means that the process can vary considerably.
Unfortunately discones are quite difficult to manufacture well from a mechanical viewpoint. The electrical side is relatively easy, but the mechanical is more difficult in view of the shape and the construction required.
Consider the requirements
Before looking at what discone antenna to buy, it is first best to consider what the requirements for its operation.
Factors like the frequencies it is required to cover, or its bandwidth, whether it is just to be used in conjunction with a scanner, or whether it might be required for transmitting, and also what antenna fixings and connectors are required.
Cost is also another important issue. This often has a major impact on the choice as the cost limitations are often one aspect that places a significant limitation on what can be bought.
A little thought about how and where it is to be used will help define what is really needed and help selecting the best discone to buy.
Discone antenna specifications
There are various specifications that need to be noted when looking for a discone antenna to buy.
- Bandwidth: One of the main advantages of the discone antenna is its bandwidth. Often a frequency span of 10:1 can be achieved. When looking at choosing a discone antenna to buy, it is necessary to ensure that it best meets the needs of any requirements.
Typically the discone is likely to be used with a scanner, so it is best to make sure the antenna covers the frequencies of interest. As the discone will have a lower frequency limit which is likely to be above that of the scanner, ensure it meets the needs of which bands are of interest.
- Quality / manufacturer: One of the major considerations when buying a discone antenna is the quality of its construction. A good indication of its quality can be gained from a knowledge of how the manufacturer is perceived.
Some manufacturers will produce good quality, whereas others might be manufactured to a cost. There is a cost / quality balance, so opt for a manufacturer who offers what you want. Also read any reviews that might be available as these will give an indication about the quality before committing one's hard earned cash towards one.
- Additional vertical element: Some discones have an additional vertical element that extends above the main discone section of the antenna. This is used to extend the low frequency performance of the overall antenna.
It is worth remembering that the additional vertical element does increase the windage for the antenna and increase its visual impact. A balance needs to be made when considering exactly what type of discone to buy.
- Power rating: Although discone antennas are not widely used for transmitting as they do not offer any directional properties, there is no reason why they should not be used. If transmitting is a consideration, then check the power handling capability, and ensure that it will be able to handle the power levels that will be transmitted. Often they will be able to handle 200 watts or so, so for most stations this should not be an issue. But always check what the maximum power rating is.
- Windage Windage can be a significant issue in some locations. If the winds on the geographical area where the antenna is to be mounted are likely to be significant, or of the mounting arrangement is not as robust as some, this can be a major consideration.
If the antenna falls it could cause damage of injury. Consider the windage specifications and the overall quality of construction when buying a discone for windy location.
Often the windage specification will be given in one of a variety of ways. One is the wind survival defined in terms of the speed of the wind. A typical figure for a good antenna will be 90 miles per hour.
This does not determine the force created by a given wind as this will affect the mounting or tower on which the antenna is mounted.
- Antenna connector: Although not a major consideration when buying a discone, the connector used at the base of the antenna is typically a “UHF” SO239 connector for those used for scanner applications.
These connectors are often not recommended for use above about 150 MHz, but in reality the high quality versions can easily work well up to 500 MHz or more. The key issue is to buy a good one and not one of the low cost and low quality connectors that abound on the market.
The other major issue is to make sure they are tightened correctly. This has a major impact on the performance.
Military grade discone antennas will typically use N-type connectors, but the cost of the military grade discones will be very much more.
Whatever the connector used, it can be advantageous to seal around the connector to prevent moisture ingress which can affect the coax cable performance as well as introducing corrosion on the actual connector. Self amalgamating take is ideal for this.
- Cost: Cost is a major issue for many antennas. There is a wide variation in the cost of discone antennas. Often you get what you pay for, so especially if the antenna is to be located externally, it is wise to pay a little more and buy a quality brand. It is better to pay a little more for the antenna, rather than have to replace a cheap one more frequently.
Discone antennas are very useful when very wideband usage is needed. Often proving a bandwidth of 10:1 they are an ideal solution for scanner reception and many other applications, both for hobbyists and for professional use That said they are seldom used for transmitting, although there is no reason why they should not be used in this way, but often better options are available.
When selecting the best discone antenna to buy it is worth spending a little time to determine what is needed, assess the market and then buy the best discone for your particular needs.
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