WRYZ926

You definitely have to check the resonance of different tin cans.

Having some type of battery backup is always a good idea. And there are different ways to set it up. I do agree that inverters going from 12V DC to 120V AC and back to 12V DC is inefficient but sometimes that is the best setup for people. I normally run my radios from a 120V power supply but also have a 50 AH LIPO4 battery for when the power goes out. Now I can't run very long on that single battery without a way to charge it. But it works for running my dual band radio during power outages. And that allows me to check on people and participate in the local Sky Warn nets. I just won't do a lot of rag chewing while using the battery. And I am still researching the best option for my house for solar panels to keep my LIPO4 batteries charged. And you can turn the power down on your radio if you do not need to run full power. That will help make a battery last longer.

Here is a good video from KM4ACK and his thoughts on why Hams need GMRS. And I have to agree that it is always good to have as many modes of communications as possible. Why Hams Need GMRS

I would say that is true for most, but not all vehicles. I know it's not true on my 2023 Ford Escape. The shark fin only has the GPS and Sirius antennas in it. The AM/FM antennas are actually built into the rear window I forget which thread these mounts were discussed in on the forum. They are a viable option for those that only run one antenna or don't mind swapping antennas out regularly. This is correct. But the gentle slope of most SUV/CUV roofs won't make a big difference. I have to run short antennas on my Escape and have the GMRS antenna towards the back. I still have at least 12 inches of metal all the way around the base for my ground plane. I do notice a very small difference between my antenna in the middle of the roof versus towards the back. But it is not enough to worry about. I was more concerned about keeping the antennas spaced to minimize any interaction between them.

Well you do want to put the antenna on a flat spot when ever possible and on the top of the vehicle. Sometimes that is not an option though. For the OP, anywhere on the roof that will not interfere with his sunroof and has at least 6 inches of metal all around the mount will work fine.

I'm sure that birds dancing around on the wire will change the SWR. Now if a person dances on the wire you will probably need new wire.

As long as you have at least 6 inches of metal all the way around the antenna mount then you should be good to go. A 6 inch radius is the recommended minimum for a good ground plane. And even "no ground plane" antennas benefit from having a good ground plane.

I would first figure out exactly how far back the sun roof goes inside the roof. You don't want the NMO mount and/or coax interfering with your sun roof. While as center as possible is ideal, you really don't need that much metal around the base for a good ground plane with UHF

I bet that will depend on if they are wet or dry on how much attenuation they cause.

I went with the 1 5/8" fence post for that reason. Plus it's easier to transport 8 foot sections versus longer sections. For those interested, here are the 1 5/8" fence post couplers I use. 4 Pieces 1-5/8" X 6" Chain Link Fence Top Rail Sleeve

Not handy. I used zip screws at each joint. I put a total of 16 zip screws into each coupler. I have 8 zip screws going through the coupler into the j-mount and 8 more into the 1 5/8" fence post Here is a photo showing a coupler on one pipe that I have ready to go for my weather station. I will repeat with 8 more zip screws when I add another pipe to the coupler.

Fence post can be used safely. You have to be smart about it and make sure each joint is mechanically attached using screws/bolts. And you also need to use proper wall anchors along with guying the mast. There are plenty of old VHF/UHF TV antennas that were installed using fence posts/top rails 30-40 years ago (if not longer) that are still standing. And VHF/UHF TV antennas are heavier and have a higher wind load than any vertical antenna. Again, proper installation is important. And not everyone can afford a tower nor is a satellite j-mount always tall enough. Be smart with your installation and your ill be just fine. PS: You can extend the height of satellite j-mounts using 1 5/8" fence posts and couplers. You will want to use guy ropes/wires when doing so. Here is my 6 band 6m - 20m cobweb antenna on a j-mount that was extended up with a 8 foot 1 /58" fence post. The coupler is properly attached to the j-mount and fence post along with everything being guyed. The cobweb has a lot more wind load than a vertical and it has withstood 50-60 mph winds just fine.

I use several zip screws at each joint. I use 1 5/8' fence post couplers. I went overboard and have three wall brackets along with the guy ring at the top. While fence posts and fence top rails aren't ideal, they do work. Just make sure to properly secure them to your structure and at each joint along with some guy ropes/wires. And keep the weight and wind load down with the antennas. I normally only put 1 antenna on each fence post mast.

I suggest using something like this EZ 43-A Adjustable 3 Way Down Guy Ring for up to 2-1/4" Mast - Heavy Duty placed right below the antenna. You can use some good Dakron rope such as 1/8 inch Black Dacron Polyester Cord for your guy rope. I like using Nite Ize CamJam Cord Tightener - Tie Down Rope Tightener with Carabiner Clip to tension the guy ropes. I use 1 5/8" fence posts for my antenna masts along with satellite dish j-mounts and guy each one with all of the above going to eye bolts or other tie off points. The biggest antenna is a 6 HF cobweb antenna that is a 8 foot square antenna. The antennas will still sway in high winds but I haven't had any issues even with 50-60 mph winds.

Let me get my tinfoil and popcorn for this one.