I worked for Kyocera Wireless over 20 years ago. I worked on the firmware. We often had to test with Faraday cages. This was CDMA 2000 days, aka 3G. They were very fine meshed cages. They were on a platform you and to walk into them. There was a test bench and instruments on a bench inside of the cage. Before that I worked for another company called Wireless Knowledge and we worked on Blackberries. We also had a cage at that place. Well before we got the cage we would use a microwave oven - :P. We were testing how our firmware behaved when no signal was detected. We later got an actual cage, but we pulled some cowboy stuff early on LOL
To include with your topic of faraday cages, I follow a popular CZcams channel for overlanding, and a couple of years ago he put out a video regarding a device he had purchased and installed on his truck to protect him from EMPs... It can be very difficult explaining why they wasted their money if they have ZERO knowledge of electronics...
I 100% agree with your points about the "faraday cage" thing -- it's an explanation that I think people started using to try to explain things they didn't fully understand and then it was picked up and repeated and became misinformation. That said, I have to disagree with the implication (or statement?) that there is no difference using an antenna inside vs outside the vehicle; putting it outside will absolutely help *a lot* vs keeping it inside any time when range is important. That has nothing to do with apertures in the vehicle not passing RF or anything silly like that -- it's a combination of other things. The simplest thing is just that when you put it outside the vehicle you generally end up with a much better antenna. I recently-ish (~18 months ago?) started selling (and testing) BNC magnetic mounts that people use to put an HT antenna outside the car and it's absolutely amazing how much more stable the SWR is; SWR is not the same as antenna performance, of course (doesn't matter how efficiently your non-resonant dummy load transfers energy) but it does help and HT antennas are so unreliable with SWR that most will give you 10 different SWR readings from 10 different measurement tools -- that's because so much of the antenna is coming from things *around* the antenna, including the HT and your arm, and anything you add to measure SWR will *change* the SWR. If you put it on a mag mount on the vehicle it becomes stable and will perform better. I would guess that *most* people who use an antenna outside the vehicle use something better than that, making the point even stronger. Additionally you usually end up with the antenna being higher in the air. It's been my experience that often when on foot or in a vehicle getting an antenna 2 feet higher off the ground can make as much difference to your signal as putting on an antenna with an extra 3dB of gain. (those numbers are arbitrary and not the result of measurement =]) Also you're more likely when holding it to end up holding it slantwise or sideway (particularly on a longer antenna like my signal sticks) which changes the polarization of the signal and can have negative impact on your signal unless the receiving station does the same. Finally, even if it isn't a faraday cage or anything there could still be interactions between the antenna and any nearby metal, either simply from being too close to it (many antennas don't work as well if too close to other metal, I suspect due to capacitive coupling but that's a guess) or else because of reflections from various metal things inside the vehicle. At the end of the day the #1 rule for "what should I use" is -- use what works. For many many things you'll find a rubber duck is really all you need. I build antennas for a living and have literally hundreds of good quality ones that I could grab at any time, but if I'm in a place where I don't need a long antenna I'll use something short like a rubber duck -- it is just easier to use! From inside a car my signal sticks are painful to use -- but putting one on the outside of the vehicle it suddenly becomes much much better. ... and now I'm rambling too much, but hopefully that was helpful to someone =] Thanks for the video, it's good to debunk common myths. (I'd like to see someone do one on how likely you actually are to damage a radio due to poor SWR, for example :-P)
I get wicked picket fencing when I transmit from inside my car. If i open the sunroof and stick the antenna out of it, it sounds better. Cars are not faraday cages, but it is most definitely not ideal to rely on an antenna inside a vehicle. Also NMO mag mounted antennas can be had for fairly cheap.
The problem with transmitting inside a car with 2 meter and 70cm radios is that the transmissions are limited as opposed to standing outside the car. Some of these people test distance of new radios while one is seated in a car. This is a bad practice and is not an accurate assessment of a pair of handi talkies. Additionally the car is emitting all kinds of radio interference with the cars ignition computer, WiFi, am-fm radio, wireless back up camera, back seat video, and even you own cell phone make all kinds of electronic noise.
I worked for Kyocera Wireless over 20 years ago. I worked on the firmware. We often had to test with Faraday cages. This was CDMA 2000 days, aka 3G. They were very fine meshed cages. They were on a platform you and to walk into them. There was a test bench and instruments on a bench inside of the cage. Before that I worked for another company called Wireless Knowledge and we worked on Blackberries. We also had a cage at that place. Well before we got the cage we would use a microwave oven - :P. We were testing how our firmware behaved when no signal was detected. We later got an actual cage, but we pulled some cowboy stuff early on LOL
Thank you.
To include with your topic of faraday cages, I follow a popular CZcams channel for overlanding, and a couple of years ago he put out a video regarding a device he had purchased and installed on his truck to protect him from EMPs... It can be very difficult explaining why they wasted their money if they have ZERO knowledge of electronics...
I 100% agree with your points about the "faraday cage" thing -- it's an explanation that I think people started using to try to explain things they didn't fully understand and then it was picked up and repeated and became misinformation.
That said, I have to disagree with the implication (or statement?) that there is no difference using an antenna inside vs outside the vehicle; putting it outside will absolutely help *a lot* vs keeping it inside any time when range is important. That has nothing to do with apertures in the vehicle not passing RF or anything silly like that -- it's a combination of other things. The simplest thing is just that when you put it outside the vehicle you generally end up with a much better antenna.
I recently-ish (~18 months ago?) started selling (and testing) BNC magnetic mounts that people use to put an HT antenna outside the car and it's absolutely amazing how much more stable the SWR is; SWR is not the same as antenna performance, of course (doesn't matter how efficiently your non-resonant dummy load transfers energy) but it does help and HT antennas are so unreliable with SWR that most will give you 10 different SWR readings from 10 different measurement tools -- that's because so much of the antenna is coming from things *around* the antenna, including the HT and your arm, and anything you add to measure SWR will *change* the SWR. If you put it on a mag mount on the vehicle it becomes stable and will perform better. I would guess that *most* people who use an antenna outside the vehicle use something better than that, making the point even stronger.
Additionally you usually end up with the antenna being higher in the air. It's been my experience that often when on foot or in a vehicle getting an antenna 2 feet higher off the ground can make as much difference to your signal as putting on an antenna with an extra 3dB of gain. (those numbers are arbitrary and not the result of measurement =]) Also you're more likely when holding it to end up holding it slantwise or sideway (particularly on a longer antenna like my signal sticks) which changes the polarization of the signal and can have negative impact on your signal unless the receiving station does the same.
Finally, even if it isn't a faraday cage or anything there could still be interactions between the antenna and any nearby metal, either simply from being too close to it (many antennas don't work as well if too close to other metal, I suspect due to capacitive coupling but that's a guess) or else because of reflections from various metal things inside the vehicle.
At the end of the day the #1 rule for "what should I use" is -- use what works. For many many things you'll find a rubber duck is really all you need. I build antennas for a living and have literally hundreds of good quality ones that I could grab at any time, but if I'm in a place where I don't need a long antenna I'll use something short like a rubber duck -- it is just easier to use! From inside a car my signal sticks are painful to use -- but putting one on the outside of the vehicle it suddenly becomes much much better.
... and now I'm rambling too much, but hopefully that was helpful to someone =] Thanks for the video, it's good to debunk common myths. (I'd like to see someone do one on how likely you actually are to damage a radio due to poor SWR, for example :-P)
Everyone needs to see this video. I get an argument whenever I ask the same questions about protection from emi.
Well done. I could nit pick some details (lightning has significant energy content up to about 1 MHz, not just 30kHz).
Thank you for clearly explaining the correct answer of this VERY Common, often repeated false assertion.
I get wicked picket fencing when I transmit from inside my car. If i open the sunroof and stick the antenna out of it, it sounds better. Cars are not faraday cages, but it is most definitely not ideal to rely on an antenna inside a vehicle. Also NMO mag mounted antennas can be had for fairly cheap.
If cars are faraday cages, how is it everyone is talking on their phone while driving ROFL
The problem with transmitting inside a car with 2 meter and 70cm radios is that the transmissions are limited as opposed to standing outside the car. Some of these people test distance of new radios while one is seated in a car. This is a bad practice and is not an accurate assessment of a pair of handi talkies. Additionally the car is emitting all kinds of radio interference with the cars ignition computer, WiFi, am-fm radio, wireless back up camera, back seat video, and even you own cell phone make all kinds of electronic noise.