ah, just learned something (I might have know had I read already some good books on the topic), and that is that a mag mount antenna does indeed somehow "establish" an equivalent ground of sort though the base. I didn't quite understand the technical explanation, though.
And talking to a guy who should know this stuff, he seemed skeptical that putting a 1/4 wave on the vertical rear hatch would be close to optimal, I imagine cuz of ground plane issues.
And talking to a guy who should know this stuff, he seemed skeptical that putting a 1/4 wave on the vertical rear hatch would be close to optimal, I imagine cuz of ground plane issues.[/QUOTE]
It isn't optimal. It's a compromise to avoid damage by obstructions. Usually when transmitting short distances. Carrying a longer antenna inside that can be swapped for the short one when needed is a good idea.
Any thoughts on mounting the antena to the rear spoiler. It wouldn't hurt me to drill some holes and mount to that. Just wondering if that would be a good surface or not?
Any thoughts on mounting the antena to the rear spoiler. It wouldn't hurt me to drill some holes and mount to that. Just wondering if that would be a good surface or not?
E-With as much difficulty as you have making decisions, and your reluctance to spend any money, I have a solution. Build your own antenna. This is a time honored Ham tradition, and the antennas can be made from everything from antenna wire to cubic zirconium. Once you read the book, you will realize I am not kidding.
This discussion is going the way of your various winch threads. At some point, just buy something, stop posting and start talking on the radio. This is not hard. Like many mods to the Land Cruiser, the first thing you do is not necessarily the last-you learn from experience what you like and don't like. There is no perfect solution, just a series of compromises based on your needs and utility.
If you are that worried, just buy a hand held radio (HT) and you'll be surprised how much you can do with 5 watts just the crappy antenna that comes with it.
You seem primarily to want to argue with the advice being given to you by Alvaro and others, based not on your own experience, but on the advice of "a guy who should know his stuff". I am not posting to any more of your radio threads until you post your call sign. Otherwise I'm not sure you are serious about this.
Andy, while trying to figure the best antenna to get, relating the fact that an expert expressed concern about asymmetries in transmission -read limitations in range- due to the vertical sheet metal when in the hatch position hardly seems to be arguing nonsensically when looking at the possibilities. If that is an incorrect assessment, I would like to know. And yes, I seem to recall you favoring this location. And no, talking about its possible limitations is not an attack on your manhood... Your input will be missed. Thanks.
Eric,
It has been posted many times by Andy and others that the optimum location for any 2-way radio antenna on a vehicle is a permanent mount in the center of the roof. This is not new information.
For many reasons, most of us don't choose to place the antenna in this "optimum" location; roof racks, garages, and reluctance to drill a hole in the roof and drop the headliner to run the coax. We then start looking for alternative locations and the hatch lip mount for the 80-series quickly pops to the top of the available options. That's where Andy mounted his as did Alvaro, Ron, Ken, me, and dozens of others. My mount and trail antenna is identical to the one posted above by Alvaro other than mine is mounted a little higher (~8") on the tailgate. On 2 different occasions I was making excellent contact with another mobile unit at distances well over 20 miles; once on I-25 and once on a state highway through the mountains. I can pick up the Mt Taylor (>10,000') repeater perfectly from my driveway. It is 85+ miles away and line-of-sight from my house (6,000'). If this is not optimal then that's OK; I can live with that kind of range and when I need more I will put on the longer antenna.
If you find a better place to mount a 2-way antenna that can be demonstrated with empirical data, then please let us know. I have no doubt that you'll do some type of testing to validate your findings.
As many have mentioned, antenna placement is important, but subjective to physical restraints. As I mentioned before, u can throw a coat hanger out the window and hit a repeater 50 mi. away.
U will notice in this picture the ultimate of UHF/VHF grounding system:
I'm using 1-1/4 inch tinned copper braid. This provides a VERY low impedance to 144 and 440 Mhz frequency signals. The transmitter will see this as a resonant antenna with a very acceptable counter-poise (ground). The whole roof (and body) of the FJ80 acts like the earth ground and the electrical other side of the antenna (the whole vehicle becomes the antenna). U do not need to do this kind of thing. What others have done will work quite well. Only weirdo's like me do this kind of stuff [I've been doing this for 40 years]. If u were in Denver, I'd guide u thru the basics.
One of the things that most people miss on mobile systems (with respect to this forum) is the noise problem. The FJ80 series is one of the most quite ( very low RFI) platforms for a vehicle (the FJ40 is serious noisey).
As an FCC licensed amateur and a member, u will have access to tech data that most people have never heard of.
Joining the club is a good thing; some of the articles in ARRL are used by NASA in some of their space flights. I aint s***ting u, I used to work for NASA. ( minute man three project).
Decided to go with good qualitiy antennas rather than skimp on that. Got 2 Comets, the shorty flex SBB1 that Andy and others got and the bigger SBB5 which is foldable. Both highly rated on eham. That should be a very versatile combo.
Both NMO. Got a Larsen Mag mount NMO also.
Will likely get a rack or lip mount later on.
I realize a front bumper mount would not be the greatest location, but I have a 40 that will be a (one of these days) a softtop, hence no roof or hatch with a lip for 'optimum' placement.
I thought about a mount on the tire carrier, but this seems like it would be worse than the bumper (for a ground plane anyways).
Another option would be a hole through the side of the tub, but I'm worried about whipping the top (which would also be problem with the tire carrier mount).
I suppose I could use a mag right in the center of my hood.
Any other reasonable suggestions?
Thanks,
John Ra
K6JMR
p.s. I'm thinking dual band if that make a difference.
didn't somebody mentioned that a 40 was particularly bad noisewise?
I was just playing around with my antenna tonight. I got a good station going and then went outside and moved the antenna around. It was pretty obvious the reception was dropping out very quickly away from high up on the roof. Down a bit on one side and nothing was coming through. I didn't do it with the engine running but you may want to do that. I would not recommend you hold on to it while transmitting, though...
Oh Boy,
I have all the same questions.
But I am going to wait until June 5th 2010 to take the test. After that I am going to bug you all with the same questions.
