Production of 2m wave 4-unit box radio for amateur radio

Amateur radio is a tool used by amateur radio enthusiasts to study radio communication technology and conduct technical exchanges, training and competitions. This article introduces the cubICal quad antenna used for 2m wave communication. Combined with an antenna rotator and azimuth controller, it can effectively communicate with amateur radio enthusiasts.

The square frame antenna has the advantages of strong directivity, high gain, easy matching and easy production. Now we will take 145MHz as an example to introduce the production of a 4-unit square antenna. As shown in Figure 1, the square frame antenna is composed of a guiding oscillator, an active oscillator and a reflecting oscillator. The length and spacing dimensions of the vibrator are marked on the figure, in mm. Considering the wind resistance and ease of production, the author uses commercially available aluminum alloy strips as the vibrator. The folding method of the oscillator is shown in Figure 2. Open one end of the square frame and drill a few small holes to adjust the circumference of the entire frame. Support it with epoxy strips in the middle, and a guide vibrator is ready. In the same way, another directing oscillator and a reflecting oscillator can be made. The method of making an active oscillator is shown in Figure 3. The middle opening on one side of the box is opened, and both ends are fixed on the epoxy strips and used as feed points to connect the feed lines.

The antenna crossbar is a commercially available aluminum alloy square tube of 25mmX25mm, and the crossbar is about 1.2m long. The connection between each vibrator and the crossbar can be done by first fixing the epoxy strip on a short section of square tube, and then fixing the square tube on the crossbar. The feed point of the antenna's active vibrator can be directly connected to the 50-ohm RF cable without any matching device. During installation, attention must be paid to the placement of the feed side of the active vibrator (Figure 4). Radio amateurs use the orientation shown in Figure 4(b) for the 2m band. After the wireless installation is completed, it can be adjusted. You only need to install the transmitter and standing wave ratio meter, increase or decrease the active oscillator and the length of each oscillator to make SWR=1.