WiMo Yagis 1296 MHz (23 cm, SHF)

Technical description

The SHF Yagis

The 23 and 13 cm bands belong to the UHF bands with the highest frequencies and offer very unique and fascinating propagation conditions. Here, antennas with high gain are essential to achieve good results in contests or DX. Due to the relatively short wavelength, the demands on precision in antenna construction are significantly higher than, for example, on 2m. Here, an error of a few millimetres has a very significant effect and can lead to poor matching or non-optimal gain.

The WiMo SHF Yagis for 23 and 13 cm are based on the proven design of DL6WU. The square boom tubes are drilled in one piece on an automatic production machine to keep the tolerances as low as possible. In the same way, the aluminium elements are automatically sawn with a maximum length tolerance of 0.1mm. These elements are then inserted and fixed into the boom with precise centring. The dipole uses a balun made of semi-rigid coaxial cable, making it very robust and accurate to manufacture. In addition, the connections of the balun are covered with protective lacquer and the connection box is sprayed waterproof. Of course, the dipoles for the WiMo Yagis have an N-connector. For 'hanging' systems, the baluns are also offered with 180° phase reversal, which simplifies the laying of coaxial cables for stacked antenna systems considerably. The dipoles are also offered individually as spare parts.

To keep the noise caused by side lobes low, a reflector with 8 elements is used. This ensures a good gain/temperature ratio, which is particularly important for EME and satellite operation. Here, the antennas are also adjusted in elevation so that the end points to the ground. And a lot of 'man-made noise' comes from the ground. The WiMo SHF antennas are delivered pre-assembled, only the boom parts have to be mounted. The shortest designs of the Yagis are designed for foremast mounting, the longer models have a downstand and have to be installed on the end of the rotating tube or a boom.

Application description

The SHF-2328 Yagi (28 elements)

The SHF-2328 Yagi is the smallest of the 23cm Yagis produced by WiMo. Nevertheless it offers a high gain of 17 dBi. With a length of only 160cm it fits into any antenna system (foremast mounting) and offers a good entry into the world of 23cm. If you drill cross holes in the boom, you can also mount this antenna vertically, e.g. for relay operation. The dipole with N-connector can handle up to 500W.

The SHF-2344 Yagi (44 elements)

With its 3m length and 20 dBi gain, the SHF-2344 Yagi is perfectly suited to be operated individually or as a group. The bandwidth of the antenna covers the whole 23cm band without any losses, even in rain it does not detune. The dipole (N-socket) is loadable up to 500W. This antenna can only be mounted at one end of the tube (boom, mast top) because of the downtube.

The SHF-2367 antenna (67 elements)

To our knowledge, the longest industrially manufactured 23cm antenna. With 22 λ length and almost 20 dBD gain it is a top product of the antenna industry. All mounting parts and screws are made of stainless steel. Due to the 8-fold reflector, the antenna has a very high front-to-back ratio. With 19.9 dBD gain, corresponding to 22 dB above the omnidirectional antenna, and a side lobe suppression of 17 dB, it follows exactly the physical laws for gain-optimised antennas. E- and H-opening angles are almost the same and facilitate the interconnection of several Yagis to maximum gain groups. The antenna covers the entire 23cm band and does not tune itself out of the band even in rain. The beam is designed in such a way that the antenna sags very little. A dipole is of course included. The maximum transmit power is 500W. This antenna can only be mounted at one end of the tube (boom, mast top) because of the downstand beam.

Choice of dipoles

The 23cm SHF Yagis are offered with either a 'standard' or a special dipole (180°). This facilitates the construction of a group of antennas (1x2, 2x2 etc.).

Antennas with a normal dipole have the cable exit downwards (for normal mounting), antennas with a 180° dipole have the cable exit upwards (for normal mounting). This makes it much easier to couple 2 or 4 antennas with cables of exactly the same length to a 3dB divider (splitter) positioned in the middle.

Both dipoles are also available individually as spare parts.