Biquad

Biquad antenna is also known as Double Quad Beam or some call it Bowtie Beam antenna (Bowtie Beam is also the name for the subtype of the Biconical antenna). It is widely used because of its properties:

  • Compact and thus can be portable,
  • Easy to make,
  • Cheap,
  • Only one radiating element and reflector,
  • 11dBi gain,
  • SWR as low as 1.05 if made ideally,
  • 50Ω impedance,
  • Equal radiation pattern in horizontal and vertical planes,
  • Good bandwidth, better than Yagi.

Dimensions of the reflector are not crucial. By Trevor Marshal, it should be .9 x .9 of the wavelength, but it was discovered that 1.2 x 1.6 wavelengths gives the largest gain. In the table we will list both values (the larger reflector will give us less than 1dBi gain over the smaller one). Distance of radiating element from reflector is from the center of the wire.

  • w – Reflector width,
  • h – Reflector height,
  • x – Outer Side Length,
  • y – Inner Side Length.
  • All measurements are in mm.

01 biquad

18

02 radiation pattern 03 radiation pattern
04 radiation pattern

Radiation pattern in Vertical and Horizontal plane. Image below: in 3D

Orientation and polarization are not intuitive as with Yagi antenna. See the image for proper orientation.

05 biquad orientation


Share This