Antenna Questions

J

jyeager

New member
Yes I searched! There may be threads that answer exactly my question too...But if so, I'm too dense to understand the details.
Yes, I'm a complete radio neophyte, but plan to get a radio in my truck, and take the test to get licensed.

I'm a planner. So I plan to get a dual band 2m/70cm mobile for the truck and I'm wondering what would be the best antenna arrangement. For the most part, I'm sure there's no right answer for everyone because everyone has a different vehicle and different priorities.
My priority will be radio performance. Unfortunately some thought has to be given to low clearance and parking garages.

I would consider getting 2 antennas though...one for best performance in open territory and one that can be used daily that would survive parking garages for instance. ( or 4 antennas if I should have a separate one for each band)

I have a Pathfinder with a roof rack. There is still open roof-top area where I could mount antennas, but how 'directional' would the antenna(s) become if they are towards the front of the roof rather than center?

How much performance loss is there putting an antenna on the front fender versus that same antenna on the roof?

If I get a very flexible whip, are there performance losses between that design and any other antenna types of the same length? If so, how much?

Should I get a dual band antenna like the Larsen 2/70? Or should I get 2 separate antennas for 2m and 70cm? (and if so, what's involved in doing that?)

Would mounting to my roof rack give good performance? I assume it would compromise radio performance, so won't try it unless it's possible for it to work very well perhaps by carefully bonding the rack to the roof?

I can read about all the options, but what I'm missing in those discussions is anything quantifying the loss in radio performance from each option. Most people seem to be considering convenience and durability and just feel that "good enough is good enough". Seems to me that I should optimize the radio's performance.

Advice?
Thanks.
 
L

lysol

Explorer
jyeager said:
Yes I searched! There may be threads that answer exactly my question too...But if so, I'm too dense to understand the details.
Yes, I'm a complete radio neophyte, but plan to get a radio in my truck, and take the test to get licensed.

I'm a planner. So I plan to get a dual band 2m/70cm mobile for the truck and I'm wondering what would be the best antenna arrangement. For the most part, I'm sure there's no right answer for everyone because everyone has a different vehicle and different priorities.
My priority will be radio performance. Unfortunately some thought has to be given to low clearance and parking garages.

I would consider getting 2 antennas though...one for best performance in open territory and one that can be used daily that would survive parking garages for instance. ( or 4 antennas if I should have a separate one for each band)

I have a Pathfinder with a roof rack. There is still open roof-top area where I could mount antennas, but how 'directional' would the antenna(s) become if they are towards the front of the roof rather than center?

How much performance loss is there putting an antenna on the front fender versus that same antenna on the roof?

If I get a very flexible whip, are there performance losses between that design and any other antenna types of the same length? If so, how much?

Should I get a dual band antenna like the Larsen 2/70? Or should I get 2 separate antennas for 2m and 70cm? (and if so, what's involved in doing that?)

Would mounting to my roof rack give good performance? I assume it would compromise radio performance, so won't try it unless it's possible for it to work very well perhaps by carefully bonding the rack to the roof?

I can read about all the options, but what I'm missing in those discussions is anything quantifying the loss in radio performance from each option. Most people seem to be considering convenience and durability and just feel that "good enough is good enough". Seems to me that I should optimize the radio's performance.

Advice?
Thanks.
Click to expand...

Have you thought about a 1/2 wave ground independent antenna along with a Diamond K9000 motorized antenna mount? That would work with a single 2/70 antenna so you would only need to install 1.

https://www.google.com/search?q=dia...a=X&ei=ix93VcbYKIORyASVkoHYBg&ved=0CAcQ_AUoAg
 
TomOwen

TomOwen

Observer
We have quite a few HAM operators in the NorCal Land Rover Club and the most popular and effective antenna is the NR770HBNMO Mobile antenna 2m/70cm, NMO mount. Great range, durability, had a fold down feature.... I run a comet sb-1 nmo rubber duck type full time on my rack (vfo on trails, repeaters around town, etc...) but when distance matters (long range simplex) I'll swap to the 770.

Good luck and 73's

Tom
 
J

jyeager

New member
lysol said:
Have you thought about a 1/2 wave ground independent antenna along with a Diamond K9000 motorized antenna mount? That would work with a single 2/70 antenna so you would only need to install 1.

https://www.google.com/search?q=dia...a=X&ei=ix93VcbYKIORyASVkoHYBg&ved=0CAcQ_AUoAg
Click to expand...


Thanks for your suggestion. I have heard that no ground plan antennas give up 15% performance over ground plane antennas. But if I were to place my antennas on the corner of my roof, perhaps the signal would be so directional that a non-ground plane antenna would be a better overall performer?
 
A

AlbanyTom

Adventurer
Best performing antenna? I'd put a dual band NMO antenna, about 20" tall, on the cab. Not on the corners, not on the roof rack. Those locations will work, but not as well. If you don't want to drill a hole in the roof of your truck, take it to a commercial radio shop, they'll do it for you for a fee - not cheap, but likely done well.

I would not put a taller antenna on it, because I do not believe they perform any better than a 1/4 wave antenna for mobile, which is about 17" single 2m. The possible exception is a 5/8 wave single band 2m antenna, which will have a base loading coil and might run a little bit better on 2m. I say that based on running different larson 5/8s and various 1/4 waves on different vehicles.

Now the above assumes hilly country, where you want to have coverage for repeaters that are quite a bit higher than you are. For flat country, those tall dual band antennas might work significantly better than 1/4 waves. Here, they don't seem to.

For sure, location is more important for a mobile antenna than the antenna, as long as the antenna is 1/4 wave or roughly equivalent. By that, I mean the db gain numbers from antenna manufacturers are meaningless, and that good to bad locations on the truck will likely be 3dB or more.

For my Xterra, I put a single band 2m 1/4 wave NMO antenna on the roof, in between the front cargo compartment and roof rack. I did that because it's the best location for this vehicle, and the flexible single band whip is much more bendy than any dual band. I have a dual band radio, but not much use for 440. I park in garages every day.
 
J

jyeager

New member
Thank you everyone.
So what about this plan? I will say to heck with the roof rack and put the antenna directly in the center of my roof, sticking up between the roof rack. With an NMO mount, I can easily remove the antenna if/when necessary. But I will bet that I can pack around the antenna (knowing that I don't want the whip to ever touch metal). I think I will get the Larsen.

I will get a dual band antenna in the 19" range and perhaps one that is twice that long for use in open country if necessary.

I am thinking that a 19" whip antenna, having it's base protected by the rack, will be fine on the roof. It should bend/flex nicely if I leave it on entering the garage. If you have any concerns about that statement, let me know. I can certainly remove it before entering, or get a Diamond with a folding base.
 
BigSwede

BigSwede

The Credible Hulk
Don't forget about tree branches. A center roof antenna would get destroyed on some of the woods trails I have been on.
 
J

jyeager

New member
BigSwede said:
Don't forget about tree branches. A center roof antenna would get destroyed on some of the woods trails I have been on.
Click to expand...

Yes. Thanks for that. I have heard many people saying that their Larsen whip antennas on NMO mounts survive very well with overhead branches....In my case, I'm leaning towards mounting it within the cross-bars of my Yakima rack so the first 5 inches will be very protected.

Do you think that will be sufficient, or should I still be concerned?

Thanks again.
 
B

BettysNephew

New member
You might look at Austin Antenna 500C Soft top. The upper section is super flexible (I doubt It can be broken) and the base is on an enclosed spring. Paul was very pleasant to work with.
 
A

AlbanyTom

Adventurer
jyeager said:
Yes. Thanks for that. I have heard many people saying that their Larsen whip antennas on NMO mounts survive very well with overhead branches....In my case, I'm leaning towards mounting it within the cross-bars of my Yakima rack so the first 5 inches will be very protected.

Do you think that will be sufficient, or should I still be concerned?

Thanks again.
Click to expand...

I think it's a great plan. How much you have to worry about branches depends on how flexible your particular antenna is, how fast you drive, and how big the branches are. I take my 1/4 wave through a parking garage every day, going slow, and hit concrete beams 3 times on the way in, 3 times on the way out. Going slow, but concrete doesn't give much.

I don't think you'll need a longer antenna. I wasn't joking about the gain of longer antennas being mythical. Putting it on the middle of the roof is a great spot.
 
J

jyeager

New member
What about CB?

If I could impose upon you to ask a follow up question....

I also have a CB I'm going to install for interoperability with others.
A CB antenna will necessarily be longer since 1/4 wave is almost 8 feet.
Now I could go for an 8 foot antenna mounted low on the quarter panel or bumper.....but I understand these locations are not good for antennas, but the longer antenna length must make up for that somewhat... and I can fold it forward to a bracket to tuck it down when not in use...is that right?

I could go with a 4' antenna (1/8 wave, I suppose?) but I figure that placing that one on the roof might be a non-starter unless it folds down...but that's something I would be content with.

I see a lot of people mounting a 4' firestick on the front fender opposite their factory stereo antenna.

Since I'm looking at at least 4' of antenna, should I be looking at a spring mount?

Having the antenna mounted to the rear bumper or spare carrier in the back sure looks cool, but can't be very efficient.


Am I right in assuming the 2 best places to consider are the front fender and the roof? If roof, how far away from my dual band antenna do I need to place it?

Am I a red-headed stepchild for considering CB??? ;)
 
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