Another antenna question

[jcefd10]

So here goes.
our ambulance right now uses a 1/4 wave mounted on top of the box. They’ve ripped 2 of them completely off, and torn the mast out of 2 more because of low hanging limbs and also the clearance of the bay door.
So, my question is if I were to mount a new coax in the roof of the cab, and use say a 5/8 wave antenna ( or whateveri need that is gal l enough to just peek over the top of the box), would their coverage be copromised at all? That’s one of the only ways I’ve come
Up with to reduce the damage to the antennas.

 

[mmckenna]

Yes, it would impact performance, but compared to having no antenna at all, it's an option.

What band do you use?
How much clearance do you have?

 

[KK6ZTE]

So here goes.
our ambulance right now uses a 1/4 wave mounted on top of the box. They’ve ripped 2 of them completely off, and torn the mast out of 2 more because of low hanging limbs and also the clearance of the bay door.
So, my question is if I were to mount a new coax in the roof of the cab, and use say a 5/8 wave antenna ( or whateveri need that is gal l enough to just peek over the top of the box), would their coverage be copromised at all? That’s one of the only ways I’ve come
Up with to reduce the damage to the antennas.

Have you tried the Stico flexi-whip 1/4 wave? It's cured a few similar situations. Or have they torn out the base/chrome nut?

 

[WB9YBM]

So here goes.
our ambulance right now uses a 1/4 wave mounted on top of the box. They’ve ripped 2 of them completely off, and torn the mast out of 2 more because of low hanging limbs and also the clearance of the bay door.
So, my question is if I were to mount a new coax in the roof of the cab, and use say a 5/8 wave antenna ( or whateveri need that is gal l enough to just peek over the top of the box), would their coverage be copromised at all? That’s one of the only ways I’ve come
Up with to reduce the damage to the antennas.

Most (if not all) the 5/8 antennas I've seen have a coil on the bottom; I haven't experimented a lot with the flexibility of those coils but I wonder if they'll flex enough to mitigate potential damage? (Just thinking out loud here...)

 

[jonwienke]

That’s one of the only ways I’ve come
Up with to reduce the damage to the antennas.

Has anyone considered making the driver pay for repairs when the antenna is damaged? That tends to put a damper on unnecessary equipment damages.

 

[jcefd10]

Yes, it would impact performance, but compared to having no antenna at all, it's an option.

What band do you use?
How much clearance do you have?

The repeater is 155RX and 159TX

Oh, and clearance is TIGHT when they are backing in the bay. I used to put the cheap-o chrome nut 1/4 wave on there. They seemed to last forever.

Have you tried the Stico flexi-whip 1/4 wave? It's cured a few similar situations. Or have they torn out the base/chrome nut?

No, I haven’t tried that yet. I actually forgot about those. They HAVE torn the entire nmo mount out before but luckily the antennas broke the last 2 times.

Most (if not all) the 5/8 antennas I've seen have a coil on the bottom; I haven't experimented a lot with the flexibility of those coils but I wonder if they'll flex enough to mitigate potential damage? (Just thinking out loud here...)

I was thinking that the whip would be long enough if mounted on the cab that it would flex enough when something hit it that was box height or above, to not break or bend. I may be thinking of a 1/2 wave that had a whip that long. Not sure

Has anyone considered making the driver pay for repairs when the antenna is damaged? That tends to put a damper on unnecessary equipment damages.

Everybody played stupid when I was there replacing it. “Whaaaaaat? It’s broke?? How’d that happen!!?!??”
And it wasn’t broke when they left for the call 😳

 

[krokus]

There are low profile antennas, which can be useful in taller vehicles.

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[mmckenna]

I agree, Sti-Co is probably your best bet.

A 1/2 wave or 5/8 wave would be my second choice. Having it mounted off to the side and below cab height is going to impact performance, and maybe to the point of being unreliable. Also, having RF that close to the driver may not be your best choice.

Or, a higher bay.
Or, let the air out of the tires before pulling in, and air them up before rolling on a call. (yes, I'm kidding for those that do not have a sense of humor).

 

[mmckenna]

I'd really caution against the low profile antennas. Very narrow bandwidth and only good up to 60 watts on VHF. Everyone (yes, everyone) that I know that has tried those have replaced them.

 

[mrweather]

Those must have been some seriously low overheads to break two whips and rip the mount completely out of another! Most of the simple 1/4 wave whips I've used are incredibly flexible.

 

[KK6ZTE]

I'd give the Stico a shot before you go to the effort of running a new mount. $42 or so from Talley, depending on your discount.

 

[lu81fitter]

Those must have been some seriously low overheads to break two whips and rip the mount completely out of another! Most of the simple 1/4 wave whips I've used are incredibly flexible.

I agree. My truck is 6 ft 6 inches to the top of the roof, and my garage door opening is 7 ft and some change. I've never had a problem with an 18 in whip bending over going in and out. Here is what I have on my truck.

Laird Technologies QW152 - $12.95 : The Antenna Farm, Your two way radio source

The STICO antenna, as mentioned above, may be your best choice.
Good luck!

 

[jcefd10]

I’m going to try the Stico I do believe

 

[emtprt]

I had the same issue and the Stico antennas were the fix. I replaced all of the VHF and UHF quarter wave antennas and they have been working great

 

[jcefd10]

So I figured out today what the death of the antennas is. It's the parking decks at the hospitals! Most of the agencies that transport to any trauma center we have are on 800/900 systems, but Not us. Good old VHF lol. Anyway, THe Stico will be ordered within the next 2 days and installed.