Very believable because it is so reflective of the everyday world we're all a part of anymore. Actually there are many communications technicians that don't have a full appreciation and understanding of antennas. Amateurs used to be the backbone of commercial radio because their motivation to learn went well beyond the limits of earning a living. Using "modern" testing methods, rote memorization can now earn an Extra class license, thus the loss of prestige that it once carried.
The proper antenna certainly would have been properly kitted at the time of sale. Point being, however, that if a service call was made (after point-of-sale) that other similar looking, compatible-fitting, but actually WRONG antennas might have been pulled from the truck’s inventory, and installed on site. It sounds like that was the situation.
Unfortunately upgrading an amateur radio license to extra is not enough. I have met at least one individual who passedd the test simply by going through the sample examinations a couple hundred times and memorizing all of the correct answers.
But understanding about feed line losses and antenna matching is "a very big deal" in the area of making a radio communication system work correctly. My guess is that the installers of the poor performance systems did not have the correct instruments, or did not use them, or perhaps did not understand the results. That does happen. And there are even some extra-class amateurs who claim that reflected power does not matter. So even that level of license is not a guarrantree of excellence.
It's always a good idea, but it's essential when you have a niche area, such as 900MHz trunked radio, that you clearly specify your technical requirements to your vendors. Otherwise, you can be taken for a ride (by accident or not) by suppliers who don't understand what you need. At JEM Engineering, we test test every single serialized antenna that we produce. We have near-field and far-field chambers, plus several analyzer types, to cover testing antennas from 30 MHZ to over 40 GHz. We even offer testing services to our competitors.
I’m laughing with a wry smile – I spent over 20 years of my career in Motorola product development and have seen your experience played out more than once. The caliber of the typical “third-party” installation guys was hard to guarantee, but as you experienced; occasionally at the level of fresh-hires direct from the Dominoes Pizza delivery routes. Lacking a thorough understanding of a radiating system, to say the least. In Engineering, product design and antenna design always went hand-in-hand, and the antenna performance was always engineered to the Nth degree in the anechoic chambers.But “fool-proofing” the antenna connection was not always done, and too often, the only guarantee that the proper antenna P/N was used would be the fine-print in the Field Service manual. So many looked alike, it could have been easily overlooked; either accidentally, or intentionally, as you suggested.But more likely, it was “accidentally” due to the limited technical skills of the installers.
What should be the perception of a product’s real-world performance with regard to the published spec sheet? While it is easy to assume that the product will operate according to spec, what variables should be considered, and is that a designer obligation or a customer responsibility? Or both?
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