Have You Heard About a Quagi Antenna?

 Well, I heard of a Quagi Antenna only yesterday, from VU2YE, a veteran LEO satellite operator in this region. He used to do even Moon Bounce with a long Quagi Antenna. Most of you would have heard of Yagi antennas or Yagi-Uda antennas and some of you would have heard of Quad or Cubical Quad antennas. Quagi antenna is one which combines the best aspects of both Quad and Yagi antennas. Typically a Quagi antenna has Quad driven element and reflector and Yagi director elements. Quad driven element is meant to take away the inherent disadvantages of a dipole. Gamma match can become less effective at VHF and UHF frequencies and I have found making and tuning a Gamma match for my VHF and UHF antennas quite cumbersome. Quagi is directly fed with 50 Ohms coaxial cable like RG-8/U as the impedance is around 60 Ohms at resonance.


Quad loops can give a little extra gain than dipole driven elements as well. A two element quad may have 1.5 dB extra gain, but this does not increase much as the number of elements are increased. That is where a Quagi design comes in, with driven element and reflector of quad design and director elements of Yagi design! An important advantage cited for a Quagi is that it has more gain for a given length of boom compared to a Yagi. Quagi is not considered much at frequencies below 144 MHz because of the higher weight and wind loading. Boom of wood or fibre glass are preferred for Quagi antennas. Feed line has to be kept at right angles to the antenna orientation. Arrays of up to 16 Quagis have been made using phasing lines. In case you wish to try building a Quagi for VHF or UHF operations, a good article is available at Amateur Radio Wiki.

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