Screwdriver Antenna

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There is no denying that are a lot of different types of antennas in the radio communication industry. Although they all have their fair share of pros, cons, and specific qualities, they all perform one function; transmitting and/or receiving radio signals for clear and smooth communication. In this article, we will be taking a more in-depth look at one of the many types of antennas; the screwdriver antenna. So, let’s jump right, shall we?

What is a Screwdriver Antenna?

A screwdriver antenna is a vertical antenna that has an adjustable center-loading coil that can be adjusted to cover any band between 10m and 75m, without compromising audio quality. You may be wondering why it’s called a screwdriver antenna. Well, the reason behind its name is because it uses a DC electric motor like that of an electric screwdriver. Because of its advantages, a screwdriver antenna is mainly used in vehicles.

Let’s now take a look at how this antenna operates, shall we? But before that, here’s an interesting fact about screwdriver antennas.Did you know that the original DK-3 screwdriver antenna design was created by Donald K Johnson W6AAQ, author of the book series “HF mobile ring”, which led to the first screwdriver antenna being invented in 1991? Well, now you know.

How does a Screwdriver Antenna work?

A screwdriver antenna mainly uses a loading coil with a whip antenna which is normally between 102” and 120” like those used for 11-meter CB radio installation. The only difference is that its loading coil can be adjusted to cover multiple High Frequency bands.

The antenna basically receives signals from the outside, and then works on them using the reversible DC motor inside. So, how does it work? When a signal is received, the DC motor, operated remotely by a DPDT switch, moves the whip and loading coil, so that part of the coil is inside the antenna’s base and electrically inactive. The other part of the coil is then used as a loading coil to be tuned for the selected band.

When changing frequencies, the loading coil is automatically extended or retracted to tune the antenna to the new band, so an external antenna is not needed.

So, what are the benefits of a screwdriver antenna?

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Benefits of a Screwdriver Antenna

  1. It is convenient

Unlike other types of antennas, you can tune a screwdriver antenna to your desired frequency just by pushing the DPDT switch at the comfort of your driver’s seat. So, you do not have to constantly stop your vehicle and climb on top to adjust the stingers or change the resonators, which is a daunting task and sometimes dangerous. The best thing about it is that you can comfortably tune it even when driving at a high speed.

  • It is reliable and durable

Since it is installed outside the vehicle, a screwdriver antenna has a robust structure, enabling it to withstand even the harshest weather conditions.

  • Exceptional performance

Apart from functioning perfectly even at highway speed, a mobile screwdriver antenna can cover multiple High Frequency bands, which significantly increases your transmit range. What’s more, it also provides a continuous coverage of frequency ranges, which enables you to have reliable communication. Of course, all this is possible if it is mounted on a secure surface and has great stability.

  • It is easy to install

A screwdriver antenna can easily be installed on top of any vehicle be it a car, a truck, you name it. This makes it one of the best antennas for newbies.

  • It is easy to build one

The truth is, most screwdriver antennas are quite expensive. Luckily there a lot of articles, video tutorials, and even books on how you can build your own hf screwdriver antenna, dk3 screwdriver antenna or ham radio screwdriver antenna to your preferred frequency and length. Isn’t that amazing?

  • Its parts are easily replaceable

Compared to other types of antennas, the parts of a screwdriver antenna like the DC motor are easily replaceable if any problems might occur. So, you do not have to worry about looking for a new component if any of them begins having some problems.

  • It tends to have  a low radiation angle

A screwdriver antenna, which is a type of a vertical antenna has a low radiation angle, which means that you can operate at a wider transmit range with the radiation patterns being uniform.

However, there are a few downsides. For starters, most ham radio operators have pointed out that screwdriver antennas tend to easily pick up a lot man-made noise, resulting to poor audio quality. Also, if not installed properly with the correct equipment, they can easily detach themselves, which cause it to either not perform perfectly, or fall down and get spoilt.

Like we mentioned earlier, screwdriver antennas are expensive. In fact, some of them cost over $500, which is why most radio operators opt to build their own antennas.

The durability of a screwdriver also depends on the environment. Since it is mounted outside, there are some environments that can negatively affect both its performance and durability. That is why it is important to pay attention to the overall structure of your antenna and the environment you will be operating your radio on.

Most ham radio operators, especially newbies have pointed out that it is quite difficult to build a screwdriver antenna. Luckily there are a lot of video tutorials and articles that have step-by-step guidelines on how to build one. However, if you are still not quite sure on how to build it, you can seek assistance from experienced operators in your ham radio community.

Frequently Asked Questions

1. What are the main parts of a screwdriver antenna?

The essential parts of a screwdriver antenna depend on a couple of factors, especially if you are building one on your own. However, there are some vital parts that have to be there for it to work perfectly. These parts include;

  • A whip antenna
  • Loading coil
  • A DPDT switch
  • A DC motor
  • A drive rod

2. Is a screwdriver antenna also called a whip antenna?

No. A whip antenna is a kind of an antenna that looks a whip or rod with a connector at its end. A screwdriver antenna actually needs it to be able to perfectly capture radio signals on the outside.

3. Once installed, can a screwdriver antenna be easily detached?

Yes, if you properly mounted the antenna then detaching it is pretty straightforward. So, always make sure that you have correctly installed the screwdriver antenna. If you’re not sure, it wouldn’t hurt to ask for help or better still you can go through the different step-by-step guidelines on how to install a screwdriver antenna on the internet.

4. Can a screwdriver antenna capture signals from all directions?

Yes, again if installed properly, a screwdriver antenna can capture signals from all directions within the selected frequency band.

Conclusion on Screwdriver Antenna

Since its invention, a screwdriver antenna has become one of the best type of antennas for mobile operation. Performing perfectly even when the vehicle is at a high speed, adjustable enough to cover a wide range of frequency bands without compromising the audio quality, and the ability to tune it at the comfort of your driver’s seat, this antenna is the real deal.

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