Antenna in trunk

katt02

Katt
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Hi all,

I am looking into putting a mobile rig in my car. I have a Hyundai with a hatchback which makes antenna mounting difficult. I wanted to do an nmo lip mount, however that will not work on a hatchback: I do not want to drill holes in the car, and I am not a fan of the bulkiness and...not so sturdiness... of magnet mounts. Anyways, what would happen if I were to put a 2 meter quarter wave antenna inside the hatchback trunk? I understand that it would be pretty detrimental towards all signals, but does anyone think would it still work for local communications or for local repeaters? Is there a way to calculate how much signal loss I would get from keeping the antenna inside the car? Finally, would this be a bad idea; i.e would it be bad for anything left near the antenna or people in the backseat?(the rig is only 50 watts so its not too crazy high power).


Thanks,
Katt
 

kb5udf

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An antenna inside the cabin running 5 watts would probably not exceed exposure limits and can certainly work, I've seen it done. I have a friend with a halfwave laying down horizontally on the back deck of his sedan, but I don't reccomend it. Inside the trunk would be the worst case IMHO regarding getting your signal out vs. irradiating the cabin. 50 watts in a trunk would put excessive RF in passenger compartment; don't do it.

You have options. Glass mount antennas work ok, and certainly better on vhf than an antenna in the cabin. Front hood mounts work and you may be able to get an nmo mount on the side of your hatchback that works if it adjusts in multiple planes (that's what I use for my hatchback.)
 

katt02

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Thanks for the thoughts. I will look into the side mount. I did not see that as an option before but I will check it out. I just did some tests for signal in and it was ok, however I am going to take the advice I get here and try to get the best signal outside as I can.
 

StaticDischarge

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Just a thought.. I have a friend of mine that has a jeep and he did not want what you do not want. So he found a mount that attaches to the fender body bolts under his hood. The mount is bent in such a way that it does not interfere with the closed hood or fender and you see no bolts outside. Maybe they make one for a Hyundai?
 

ko6jw_2

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I had three trunk lip mounts on my old Prius. They worked pretty well. I have both UHF and NMO. Used Diamond K400 series mounts. You would be better off with a mag mount than an antenna inside the car.
 

kayn1n32008

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Hi all,

I am looking into putting a mobile rig in my car. I have a Hyundai with a hatchback which makes antenna mounting difficult. I wanted to do an nmo lip mount, however that will not work on a hatchback: I do not want to drill holes in the car, and I am not a fan of the bulkiness and...not so sturdiness... of magnet mounts. Anyways, what would happen if I were to put a 2 meter quarter wave antenna inside the hatchback trunk? I understand that it would be pretty detrimental towards all signals, but does anyone think would it still work for local communications or for local repeaters? Is there a way to calculate how much signal loss I would get from keeping the antenna inside the car? Finally, would this be a bad idea; i.e would it be bad for anything left near the antenna or people in the backseat?(the rig is only 50 watts so its not too crazy high power).


Thanks,
Katt
A 2m antenna inside your vehicle is going to give VERY poor results. Especially on transmit. Most vehicles act like a faraday cage on 2m.
 

chief21

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If you have a luggage rack or side rails on the roof, you could probably mount an antenna near the rear of the rack/rails and run the cable inside at the top of the hatch. I've done this on several SUVs and it works well. Comet makes a special NMO mount for this application, complete with a section of skinny coax.
 

902

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Have you looked into an on-the-glass antenna? To avoid finger pointing with a dealership, I bought two PCTel on-glass antennas and put them on my vehicles. They are low profile and can handle 50 Watts. Look for model APR153. Yes, it says 150-174 MHz. I use it reliably through 2 meters. It works fine and has a good VSWR from between 2 meters to my business frequency in the 151 range. I don't care for trunk lip mounts, as the cable can cause water intrusion into the trunk (a pretty big deal during torrential downpours).
 

mrweather

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Larsen markets a glass-mount (KG144UD) that supposedly covers 144-160 MHz. I wouldn't expect dazzling results but it'll work well enough and much better than anything inside the car.
 

W5lz

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I don't have a problem about drilling holes, so that's what I would recommend if possible. There are times when it isn't possible, so I would look for a hood/fender 'gap-mount', between the hood and fender. Then maybe a mag-mount. I won't use a 'thru-glass' mount, they are typically not going to hold a very useful antenna. There is no 'standard' glass for vehicles, they all vary in different ways. Those ways may have no affect on such an antenna but I certainly wouldn't bet on it.
 

AI7PM

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1/4 wave, and not over a plane. Good luck getting a match on that.

I, too, am a "drill the hole" type. If I may ask, what is your objection to a proper NMO install? It's benefits and reduced chances of paint damage outweigh all of the marketed options that the "ham stores" offer to get around just doing it as intended. The only compromise I recommend to drilling, is the "L" bracket method in the gap between the hood and fender or trunk lid and fender. That still requires 2 or 3 small holes for stainless steel screws, but, you still get a rigid mount with a good ground. A 1/4 wave may or may not match on an "L" bracket, depending on vehicle variables.
 

KE5MC

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Katt,
I understand the issues with some of the mag mounts. It usually centers around long antenna with high wind resistance. Take a look at the Diamond link provided. I have used the MR77 for special events when the vehicle is not mine. 20 inch antenna and 2.6 in diameter magnet, one even has a fold back feature. Easy to try one out on the car and if you don't like it then you can use in the house on a metal surface to supplement a handheld if you have one.


Good Luck!
 

bharvey2

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This one is on its fourth hatchback/suv


I bought a mount very similar to that for installation on my wife's Ford Edge. The Edge has a fully glass top and the lip on the hatch is at an odd angle. This mount allows for adjustment in several planes. I mounted it up high on the hatch and used a Diamond NR-770HB antenna so that it's less dependent on a ground plane. SWR is fine across the 2M and 70cm ham bands.
 

stingray327

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If you have a luggage rack or side rails on the roof, you could probably mount an antenna near the rear of the rack/rails and run the cable inside at the top of the hatch. I've done this on several SUVs and it works well. Comet makes a special NMO mount for this application, complete with a section of skinny coax.
What is a NMO mount antenna? If can't use a magnetic mount or drill is this an antenna with some type of lip mount?
 

chief21

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The "NMO" refers only to the connector that actually mates with a similar "NMO" antenna (see the flat, brass-colored item on the trunk mount pictured in post #16, above). There are numerous types of mounts that will accept an NMO antenna... permanent mount, lip mount, rail mount, fender mount, magnet mount, etc. The type of mount can be independent of the type of antenna connector that it will accept.
 

k6cpo

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What is a NMO mount antenna? If can't use a magnetic mount or drill is this an antenna with some type of lip mount?
The "NMO" refers only to the connector that actually mates with a similar "NMO" antenna (see the flat, brass-colored item on the trunk mount pictured in post #16, above). There are numerous types of mounts that will accept an NMO antenna... permanent mount, lip mount, rail mount, fender mount, magnet mount, etc. The type of mount can be independent of the type of antenna connector that it will accept.
It's my understanding "NMO" stand for "New Motorola." It's pretty common. A friend of mine bought an old Sheriff's vehicle and all the antenna mounts on it were NMO. It made it easy for him when he installed radios because all he had to do was attache the antenna to the mound and connect the radio to the other end of the coax (which was still there.)

I have two NMO mounts on my truck. One is mounted in a hole I drilled in the cab roof and is connected to a short, spring-loaded 2m/70cm antenna (for my FTM-400XDR) and the other is a lip mount on the driver's side of the hood. It isn't currently connected to anything, but it's there if I need it.

One of the nice things about the NMO is that it's very easy to unscrew the antenna from the mount, if needed, and there are plastic caps that can be installed to protect the mount.
 
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