WiMo Yagis 144 MHz (2 m, VHF)

Technical description

Features of the WiMo Yagis

• Highest possible gain with high bandwidth and good side lobe and return loss. Thus the antennas are oriented to the requirements of serious VHF amateurs, who need a high performance antenna for long distance traffic and all modes of operation. The design principles of the Yagis were worked out with computer programs calibrated at NEC and verified by many test setups.

• Design current optimized
  Within a yagi structure, element currents should be uniform from the excitation center to the end of the antenna, not dropping too sharply. The yagis were designed for an optimal current profile. In older designs, there are jumps in the element current assignment, resulting in underutilized gain and poorer side lobe and return loss.

• Minimum number of elements
  Other Yagis of comparable length have 2-3 elements more and thus more losses. Note: Antenna gain depends first of all on the antenna length, not on the number of elements!

• Broadband elements
  Only good conducting aluminum tubes with 8 mm diameter are used for the elements. This represents the best compromise between minimum losses and the resulting wind load. Thin steel elements cause considerable additional ohmic losses and the skin effect, which is already very effective in VHF. Yagis with such elements give away more than 0.5 dB gain due to poor conductivity!

• Defined element mounting
  Long-term stable with UV-resistant polyamide clamps. This means that there is no change in the electrical data even after years.
  If the elements would be fixed directly on the boom by metallic clamps, the effective element lengths and thus the antenna data could change insidiously by oxidation in the course of time!

• Encapsulated dipole baluns
  The dipoles are real folded dipoles with Teflon baluns in the dipole box. So no forced matching with the known cladding wave problems! The connection is also made with the 2m antennas via an N-socket. The dipole boxes are absolutely weatherproof cold-welded and additionally foamed. The Teflonbalun is completely inside the dipole boxes. There is no balun loop that protrudes out of the junction boxes into the antenna and is then usually taped to the antenna more or less well! As a result, there are also no leakage problems at the twice pass of the balun loop through the dipole box.

• Robust construction
  Except for the mast clamp itself, only screws, nuts and washers made of stainless steel (V2A) are used to ensure a long service life of the antennas. The element holders are made of UV-resistant polyamide, for the cross yagis with round tube boom they are made of aluminum.

• German manual
  The manual contains all technical data and also information about sticking and interconnection of several identical antennas.

Application description

We offer the WY-Yagis in 4 different variants:

• WY-204: The small 4-element antenna is well suited for setups with limited space. Due to the small pack size and low weight, it is also good for vacation or SOTA activation. Pre-mast mounting, good for optional operation with horizontal or vertical polarization.

• WY-207: The 7-element Yagi is with only 3m length quite short and offers nevertheless good gain. Excellent for setting up a 2- or 4-element array.

• WY-208: The 8-element VHF Yagi has an improved forward/backward ratio and is therefore and due to the short design (max. length 380cm) still well suited for azimuth/elevation systems, e.g. for EME or meteorscatter.

• WY-209: The 9-element Yagi is the largest of the WiMo VHF Yagis, thus the model with the highest gain. The 5m long boom still fits on most row houses, for additional stabilization this antennas has a beam.