|Posted on July 15, 2011 at 12:07 AM|
Take a tour of how and antenna becomes an OptiBeam
Generally a market need is established by customer feedback and requests.
A simple model is generated using the latest software modeling tools, some of these tools cost $50,000 for a license.
The model is further developed adding full tapering to the elements and closely modeling the other structures such as feed system, brackets, boom etc.
Once this model is tested for convergence and accuracy and adjusted for best performance the physical work starts. To build the prototype can involve lots of machining of parts and designing assemblies to absorb stress, weight, and high wind and ice conditions
OptiBeam Antenna technologies has put a lot of effort into numerous carefully designed special assemblies and parts. Extreme mechanical stability and an outstanding visual appearance are achieved. All screws, nuts, washers, U-bolts etc. are of stainless steel and each screw used at a dynamic part of the antenna is self securing. Truly a German engineered work of art is developed.
The following close up views of the most important antenna parts show their quality.
The picture shows the element platform of a driven element (with phase line end connection + phase line stub concerning modelOB9-5).
The elements are fixed on the platform insulated by means of special UV-resistant tube insulators which come from the machine industry. The platforms are pre-worked finished parts.
The driven elements are divided with specially machine worked insulators which are already inserted in the factory.
Boom to Mast Mounting
To emphasize the mechanical strength of the boom to mast clamps instead of the usual platforms OptiBeam uses special extremely robust frames. They consist of four right angle aluminum pieces which horizontally to vertically are mounted in the opposite way.
For the mast mounting 55mm, 65mm or 75mm U-bolts can be chosen.
The boom to mast clamp is a pre assembled finished part.
Coax Connector / Phase Line
Side and rear view of the specially configured coax socket SO239, mounted on the phase line. The driven elements, arranged in a specific order on the boom, are connected with a phase line which consists of two square aluminum tubes. Hereby the drivers are driven in phase.
This system results in a totally loss free and high efficient feed of the OptiBeam multi-band Yagis. Furthermore real 50 Ohms are achieved at the feed point for all frequencies of the multi-band Yagi.
The result is an outstanding bandwidth
Coupling of the element sections 25/20 - 20/16 - 16/12mm. By means of OptiBeams specially designed 'screw-head dive in technique' and the use of stainless steel screws plus self securing nuts electrically large surface transitions as well as mechanically extremely stable connections are achieved.
Phase Line Crossing OB9-5
Side and bottom view of the one time phase line crossing at driver 17 concerning model OB9-5 which results in a perfect SWR for all 5 bands
Center boom truss assembly
Demonstration of the center boom anchoring with two high quality stainless steel rope trees, necessary for the models OB16-3 and OB9-2WARC.
The two stainless steel ropes are pre cut in the factory for the necessary length and completely pre-assembled.
Outer boom truss assembly
Close up view of the outer fixing of the steel rope with the pre assembled stainless steel thimble
One of OptiBeam test platforms allows Antenna to be quickly mounted and raised to about 80 feet above ground. But testing is done at many elevations.
Note man cage on top arm use for adjustments
The receiving test antennas are mounted on a nearby mountain ridge. The test antenna is then turned and the pattern is recorded to be compared with the model develope in software.
This procedure has become so good that they know exactly what the antenna will do, having done hundereds of correleations against the software model. The models are so good, Even the ARRL allows Optibeam to publish their antenna gain figures as well as front to back and VSWR. The ARRL had verified the early models of Optibeam and agreed with their numbers without any change.
OptiBeam now has other test platform towers at their factory now Including a 70 foot tall crank up tower as shown in this picture. That's Tom on the top of the tower mounting this large antenna.
Parts are collected and staged for packaging.
Packaging is accomplished with each element tapped together so no errors can be made in assembley. Also the boom is marked as to how it fits together and element hangers positions are marked on the boom.
Elopement hangers are pre-assembled making the final assembly job very easy and fast.
Boxes are labeled and ready for transport to the customers.
Categories: HF ANTENNA