WiMo-Yagis design by DK7ZB - uncompromising electrical and mechanical technology
Our yagi antennas are "Made in Germany" at our own production facilities. Your benefits:
• available from stock
• No spare parts worries
• Support directly from the manufacturer
• Special designs possible
Highest possible gain with high bandwidth and good sidelobe and rear attenuation. The antennas are thus geared to the requirements of serious VHF amateurs who need a high-performance antenna for long-range traffic and all operating modes. The design principles of the yagis were developed using computer programs like NEC and verified by many experimental setups.
• Current-optimized design:
Within a yagi structure, the aim is to achieve uniform, not too strongly diminuishing current in the elements from the excitation centre to the end of the antenna. The yagis were designed to achieve an optimal current profile. With older designs, there are sudden jumps in the current distribution of the elements, the result is not fully utilized gain and poorer sidelobe and back attenuation.
• Minimum number of elements
Other yagis of comparable length have 2-3 elements more and therefore more losses. Note: Antenna gain depends on the antenna length, not on the number of elements!
• Broadband elements
Only highly conductive aluminium tubes with a diameter of 8 mm are used for the elements. This represents the best compromise between minimal losses and the wind load that arises. With thin steel elements there are considerable additional losses of an ohmic nature and due to the skin effect, which is already very effective with VHF. Yagis with such elements lose more than 0.5 dB gain due to poor conductivity!
• Precision fixing
Long-term stability with UV-resistant polyamide clamps. This means that there is no change in electrical data even after years. If the elements were fixed directly to the boom by means of metallic clamps, the effective element lengths and thus the antenna data could slowly change over time due to oxidation!
• G/T optimized, see G/T lists of VE7BQH
The dipoles are real folded dipoles with Teflon balun in the dipole box. So no tricky adjustment with the known mantle wave problems! We use N connectors on all models, even 2m yagis. The dipole boxes are absolutely weatherproof cold welded and additionally foamed. The Teflon balun is completely inside the dipole boxes. There is no balun loop, which protrudes from the dipole boxes into the antenna and is then usually more or less well tapped with adhesive tape on the antenna! Therefore there are no sealing problems with the double balun loop through the dipole box.
We use elements with 8 mm diameter. This gives higher bandwidth compared to thin elements with the same gain! The resulting slightly higher wind load of the antenna is normally insignificant in today's rotors. Material of the elements:The single elements of our antennas consist of a highly conductive aluminium alloy to avoid skin effect losses. DK7ZB has calculated on the basis of K6STI's documents that due to losses caused by the skin effect, stainless steel elements in the 2m band have an additional attenuation of up to 0.8 dB! In the 70cm band the losses are of course even higher.
Firm is firm - we are not happy with steel clamp connections. In our yagis the elements are bolted to the boom with stainless steel screws to ensure perfect contact and unchanging function even after years of use. For each element we provide a 3mm hole in the boom and a stainless steel screw and assure you that none of our boom tubes are broken because of this hole!
Except for the mast clamp itself, only screws, nuts and washers 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 aluminium.
Crossed Yagis without support strut!
The boom of the cross yagis (exception: 2m 2x4-element) consists of round tube. Due to the versatile mast clamp the antennas can be mounted horizontally/vertically ('+'-form) as well as diagonally ('X'-form) on the mast. No deformation of the radiation pattern by an additional strut.
Any position of the mast clamp
All long yagis with split boom are delivered with a separate boom tube connector (except WY-214), so that the mast clamp can be fixed exactly in the center of gravity of the antenna, independent of the joint of the boom tubes.