My First Serious Antenna Construction

I had done constructing antennas albeit in a makeshift way and the results were never satisfying. I was never serious about it until recently. I had an access point which was some fifty metres away at another house and I was getting weak signals. That was the turning point, I decided to build a good high gain antenna.

It goes without saying that the first step was to do a research. After all the searchings and readings, I set my mind on the biquad antenna. It was simple, easily construct and did not have many parts plus I had the parts readily available. Suffice to say that the construction was not exactly according to the specifications given that parts were practically from scraps.

The main radiator element came from the field coil winding of a car alternator. Aluminium plate encasing a pc floppy drive was flattened and used as reflector, and an RF(?) panel connector to connect them together.

After spending some times cutting, filing, drilling and bending, the result was as in picture #1. On the downside, I had to connect a RF to BNC female connector at the back of the antenna. Another potential loss, this was not good. I improved it further by constructing another design. This time the antenna was directly connected to the RG58 cable at one end and a female BNC at the other end while being encased inside a tube. I knew that the BNC was not up to par but it’s almost there and cheaper. Furthermore my situation was not that very critical that every improvement matters. I ended up making two antennas this way with slight variations.

There was improvement in signals but still there was interference. The transmitting and receiving angles of the biquad were quite broad. I wanted to narrow it down. In the end I ended up with a narrow, almost line of sight, high gain 21 elements yagi at both ends, the access point and my client.

In retrospect, signals are best amplified immediately after the antenna and not after the loss incurred by the cable. This means that I need to spend away with a usb dongle that can be attached to the client antenna almost immediately. Then, instead of RG58, I just need a longer usb cable. I will not be doing this on the access point side because of the cost involved and the hassle of putting up the access point router and POE device to power it plus the need to protect it from the weather.

Anyway, here are the pics.