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Rigorous testing of the loop Yagi–Uda (quad) antenna show the following advantages over a dipole-based Yagi–Uda antenna made from dipoles: [10] Polarization It is easy to change polarization from vertical to horizontal, by changing the feed point. Multiband antenna It is easier to design a multiband quad antenna than a multiband Yagi antenna.
A Yagi–Uda antenna, or simply Yagi antenna, is a directional antenna consisting of two or more parallel resonant antenna elements in an end-fire array; [1] these elements are most often metal rods (or discs) acting as half-wave dipoles. [2]
A quad antenna is a self-resonant loop in a square shape; this one also includes a parasitic element.. Loop antennas may be in the shape of a circle, a square, or any other closed geometric shape that allows the total perimeter to be slightly more than one wavelength.
VK3IL - Multiband end-fed 80-10m antenna - NEC2 model file of a "MyAntennas EFHW-8010" multi-band antenna. Other retail books (such as The ARRL Antenna Book, Marcel De Canck's Advanced Antenna Modeling, and others) also include antenna model files. Most free or retail NEC software packages include an 'example' folder containing antenna model files.
Moxon antenna for the 20-meter band.The antenna is the faint rectangle of wires held in tension by the bent X-shaped support frame. Moxon antenna for the 2-meter band. The Moxon antenna or Moxon rectangle is a simple and mechanically rugged two-element parasitic array, single-frequency antenna. [1]
Radio amateurs can build the Hexbeam as a multi-band antenna to cover different frequency ranges. Popular combinations cover 20m, 15m and 10m (3 band) and 20m, 17m, 15m, 12m and 10m (5-band) ham radio bands. Hexbeams can also be built for the 40m and 30m bands. The antenna elements for the lowest frequency band are located at the exterior of ...
However, a Yagi with the same number of elements as a log-periodic would have far higher gain, as all of those elements are improving the gain of a single driven element. In its use as a television antenna, it was common to combine a log-periodic design for VHF with a Yagi for UHF, with both halves being roughly equal in size.
A Yagi–Uda antenna's maximum directivity is 8.77 dB d = 10.92 dB i. Its gain necessarily must be less than this by the factor η, which must be negative in units of dB. Neither ERP nor EIRP can be calculated without knowledge of the power accepted by the antenna, i.e., it is not correct to use units of dB d or dB i with ERP and EIRP.