Browse over 10,000 Electronics Projects using the Page Numbering provided at the bottom of each Page.

Biquad Antenna Construction

Biquad Antenna Construction

The biquad antenna is easy to build, and provides a reliable 11dBi gain, with a fairly wide beamwidth. Some very rough initial testing using the biquad as a feed on a 24dBi Conifer dish looks very promising. I also managed to get a marginal link to a 180 degree waveguide on an access point 10km away, using only the biquad by itself, connected to a 30mW RoamAbout wireless card.
When using a biquad to establish a link to another wireless device, you should ensure the polarisation of the biquad is the same as the antenna you are connecting to. Similarily, if establishing a link with two biquads, ensure they are both oriented for the same polarisation. Failing to match the polarisation will result in significant signal loss.

Changing the polarisation is just a matter of rotating the entire biquad antenna by 90 degrees.

The biquad antenna is not particularly directional, but has a fairly wide beamwidth. The 3dB beamwidth for a biquad (without side lips) is typically about 40-50 degrees, thus making it ideal for any applications where you want fairly wide coverage.

The relatively wide beamwidth also makes a biquad very suitable for war-driving and stumbling, allowing you to pick up signals without having to align the antenna directly with the signal source.

While a directional antenna, such as a Conifer dish (3dB beamwidth of a 24dBi Conifer dish is approx 7 degrees), is better suited for point-to-point links, the narrow beamwidth of a Conifer dish requires more precision when aligning the antennas (the narrower the beamwidth, the less susceptible it will be to interferance from other sources). An antenna with a wider beamwidth, such as a biquad, doesn’t require the same precision for alignment, thus making it easier to get a link working.

Visit Here for more.