An Antenna's Build Quality is as Important as the Antenna Design Itself
The electromagnetic design of an antenna is one thing but translating that design into a built antenna which provides the performance characteristics in the real world that were predicted within software is completely another. There are so many aspects which can alter and change an antennas performance. Some such changes can take months to develop while others are there immediately and are a result of the antenna being built the 'wrong way' and with the wrong materials.
Most of these issues can be covered up by matching devices used upon antennas today. Hairpin, 'T' and Gama matches all have a wide impedance matching capability and can be altered to show a good SWR on any antenna, despite the fact the antennas best performance may in reality be way above or below its intended frequency of use.
So what exactly is it that causes these issues and how can these 'pitfalls' be avoided? At InnovAntennas we have the ability to model not just free-space 'wires', we can model with extreme accuracy, all aspects of the antenna. This includes the boom, insulators, mounts and even the matching devices themselves. Some seasoned radio hams would be quick to point out that some very old DOS based programs model matching devices too, this is not the case.
These programs did not have the electromagnetic design power or capability to conduct such modelling accurately. All these programs were able to do was model the effects upon impedance the use of such a matching device would have, not model the impact the placement of the matching device within the antenna would have, and it is here where some very big errors occur leading to an inaccurate antenna being built. This said, these errors can remain unseen as they are 'masked' by the antenna's matching device. Within our tests in both software model and practical experimentation, up to 10dB F/B (front to back) and 0.5dB gain were lost through matching device insertion. Not something any manufacturer that needs to use matching devices upon its antennas would want to admit (and perhaps don't even know about it)!
At InnovAntennas we believe if an antenna is designed in the right way, no matching devices are needed and thus any negative impacts need not be considered. Furthermore, everything associated with the antenna should be modelled and tested, not added to the antenna at the time of sale and shipped! We believe the majority of antenna design and manufacture is done this (wrong) way and this is why the hundreds of hams that have installed any of the G0KSC designed antennas consider them to be 'head and shoulders' above what they have used before. We follow the G0KSC guidelines completely and model the antenna as a complete unit, as it would be when built and therefore, there is nothing being added during manufacture that could effect or alter performance.
Another large problem area is that of materials used to build the antenna and the way the antenna is constructed. One key piece of evidence to support the above claims is the widespread use of Polyamide for antenna element insulators. In most cases, Polyamide is not suitable for RF applications and can have a marked impact upon the antennas bandwidth (The Antennas Q) and general performance. Without the sophisticated software we have at our disposal and our stringent testing and high accuracy expectations, we would have not been able to establish or prove these facts. We have also established the materials that should be used (for element insulation). We understand what is the 'right' way to build antennas and regardless of cost, we build them for best performance every time, not highest profit margins!
Antenna bandwidth is another aspect of antenna design which is extremely important and so very rarely developed within commercial antennas. Typically, a wide-band antenna has a constant, near 50 Ohm impedance. This is important for many reasons but one such reason is to prevent coax radiation which can badly impact the performance of a Yagi. If you have to use a tuner within your shack to establish near 50 Ohm impedance, what is the impedance between the back of the tuner and the antenna? For optimal performance the 50 Ohm coax cable feeding the antenna should 'see' a near 50 Ohm when connected to the antenna. This will ensure your Yagi performs like a Yagi without a vertical radiating element (the coax) below it!
A tight narrow 'V' shaped SWR curve again is a common sight on highly-tuned Yagi antennas. However, this is also a sign of a very steep impedance curve which can result in antenna instability. Does your current array move out-of-band in rain, snow or ice? Now you know your problem. Install an antenna that is designed correctly and you can reduce massively any such issues allowing you to use your system whenever you wish, not when weather conditions allow.
In addition to the comprehensive set of considerations we have at the antenna electromagnetic design stage, InnovAntennas also build to the highest standards. 6063T6 aluminium, A2 and A4 stainless steel fixtures and fittings and high-quality commercially produced RF neutral insulators. You WILL NOT find electrically connected parasitic elements (to the boom) on our antennas. You will hear all kinds of stories as to why this is done as a part of antenna manufacture with others. The only benefit we have established from manufacturing this way is cost; it is much cheaper to manufacture this way. The down side is building a correct antenna from a software model is much harder to achieve and a different level of correction is required for each and every element on the antenna. furthermore, as corrosion occurs at the electrical joints (particularly on low impedance antennas where current levels are high) resistance occurs resulting in a de-tuned antenna. If your antenna has insulated elements from design to build, which can change over time, they were built insulated and remain insulated regardless of how long they have been installed!
In a nutshell Build Quality does not come down simply to the fact that we use the highest quality components, Marine grade stainless steel fittings* and RF Neutral insulators, but it does help. Rest assured if you purchase an InnovAntennas antenna, you are buying the latest in design technology and do not need to worry about whether or not the antenna will perform. This is our definition of Build Quality, the whole package being right from electromagnetic to mechanical design, through to the physical build of the antenna. 'A Bad Antenna Built Good' is common in our industry but you will not find such an antenna with InnovAntennas!
Call us, Email us or ask us. We want you to make the right decision and appreciate you need to ask the right questions before joining our family of customers.
We look forward to hearing from you soon and remember, we aim to be the best of the best, for you.
The InnovAntennas Team