One of the most important parts of the antenna is the radiating element.While different shapes will change the way the antenna works, its signal strength, and its efficiency, it is not super critical if you do not get it bang on. The radiating element can be of three shapes (see Figure 3-9):

While the cone shape is the most efficient, it is also the hardest one to make. So, we will only go into detail for the round element and wedge element. The round element is very simple to make since it is simply the core copper conductor from an LMR-400 coaxial cable (used extensively in Chapter 1). The round element also has the most narrow frequency band. If you create an antenna using the round element, effective power will drop considerably across all of the channels.

The wedge element is a bit more complex to make, but it has great coverage of the Wi-Fi channels. It’s a little less efficient than the cone, but not significantly. The wedge is worth the extra time and effort, and it’s what we use when playing with the can antenna toy.

Making the round radiating element is extremely simple because it is the core copper conductor from a coaxial cable.To make the round radiating element, follow these steps:

Once you know the length of the radiating element, you will need to make sure you have the correct length. Having said that, make sure that you don’t trim the coaxial cable to the exact length of the element. Instead, cut extra. Starting with a piece of coaxial cable that is twice the final length is a good starting point, as shown in Figure 3-11.

Using a single-sided razor blade, strip the outer jacket, inner shield, and dielectric core as described in Chapter 1. As Figure 3-12 illustrates, you will be left with just the core copper

 

conductor. Make sure that you add a little bit to the length of the connector with respect to the length determined in Table 3-2, to make sure that the radiating element can be inserted and soldered into the N-Connector.

Now that you have the core conductor to work with, start by trimming one side as square with the edge as possible. Then measure the desired distance from that trimmed edge and cut the final length. Ensure that you take into account the portion of the conductor that will fit into the N-Connector body. If you are not sure about the length, wait until after you solder the conductor into the body before making any final length adjustments.

Making a wedge radiating element is not a complex process but it does take some talent to solder it to the connector. To cover the Wi-Fi spectrum, the wedge radiating element needs to be 1 mm wide at the base (where it connects to the N-Connector) and 6 mm at the tip. Figure 3-13 shows the wedge.

One way to make this wedge is to start with a copper embossing sheet (this is available in most arts and crafts stores). Simply trace out the desired wedge shape of the radiating element and cut to size with either a knife or strong scissors.We created the wedge in Figure 3-14 using the one foot-square copper embossing sheet.

A second way to make this wedge shape is to use a hammer to hammer out the shape. As you can imagine, this process is more work-intensive, but requires less precision on your part. The object in Figure 3-15 is a cross between the wedge and round element. The forgiving nature of this antenna design allows for a good bit of fudging.

This process produces a semi-wedge-shaped element that is not as efficient as the “true” wedge radiating element, but is better than the round radiating element.