The most important part of a transmitter, besides the radio, is the antenna! Having a properly tuned antenna is not just a "nice to have", it is an absolute must. Operating your radio without an antenna or using an improper antenna can irreversibly damage your HamShield's final amplifier. This instructable will help you configure the antenna properly, depending on the frequency you wish to use. Thankfully, the Smiley Tri-Band Antenna works across all three major amateur radio bands: 144MHz, 220MHz, and 440MHz. In the 440MHz band, it can function as two different types of antennas depending on how many sections you collapse or raise.
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Step 1: Transmitting on 144MHz to 148MHz
This configuration lets you operate the antenna in 1/4 wave mode. If you want to operate in this frequency range, simply extend the antenna all of the way. Simple!
Step 2: Transmitting on 219-225 MHz
In order to operate on this band, after fully extending the antenna, collapse the 4 top sections as shown. This will make a suitable antenna for the "220" or 1.25 meter band.
Step 3: Transmitting on 420-450 MHz in 5/8 Wave Mode
If you wish to operate in the 440 band in 5/8 mode, simply collapse the two top sections. As you can see in the plot, a 5/8 wave antenna is a little bit flatter, but provides higher gain than a 1/4 wave antenna. This is useful it you want to get the most out of your antenna and your receiver is around the same elevation.
Step 4: 440 MHz in 1/4 Wave Mode
We can also use the antenna in 1/4 wave mode, which provides a much broader pattern, by collapsing all sections! This is useful if you wish to use the antenna to cover high and lower elevation areas. The gain, or total power output, is a little less, but sometimes it is useful. An additional plus is that this antenna is the smallest configuration -- fully collapsed.
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