Coverage/Propogation VHF vs UHF FM

[k4puf]

Not quite sure if this is the appropriate place to ask this question. I've had very little vhf/uhf experience and I am part of a team proposing a 2-way radio dispatch system at a University. The University is about 350acres and has many brick buildings. Some parts of the campus are also wooded. While I realize that no setup is 100% foolproof or perfect......I'm trying to decide on a Vhf or Uhf system. The "dispatch" center would be running about 25-40 watts into a vertical antenna mounted about 35 feet in the air. The "portable" radios' output is about 4-5 watts. Given the size of the campus and the setup I've described, can I expect a significant coverage/range difference between 155Mhz and 430Mhz?

[gewecke]

IF the majority of your coverage area would be inside those buildings then you might want to consider UHF as it will penetrate between floors and the other buildings better. Also depending on how many square miles of property you're covering,you may want to think about licensing a repeater.
N9ZAS.

[N_Jay]

I would suggest you have a coverage study done.

Many radio sales people can do it for free.
If it is the place trying to sell the system get a guarantee on the coverage shown.

To answer your original question, I would suggest UHF.
In general it works better in heavy buildings.

[jim202]

The comments received so far have some merit. However. I would suggest that you try both a VHF and
a UHF radio and see which covers your area better. You might try finding some ham radio operators
to see if they might help in your project.

The reason of try before you buy, is this way you can get a first hand look and see just how each
band works in your buildings and coverage area. I have found over the years that different building
construction works different ways with these 2 bands. One building may work well with VHF and
stinks with the UHF. Go to another building and the flip side shows up. This has to do with the
details on just how each building was constructed. How much steel is in the walls and ceiling.
How the cables are run in a building, what outside material is on the walls and the list goes on.

Over the years I have seen some hard nosed so called experts go down in flames on just this
subject. I use to work for a consulting company and have been involved doing just this type of
project. I too was surprised in the outcome. Do yourself a favor and do some real time testing
before you buy anything.

Jim

Originally Posted by k4puf

Not quite sure if this is the appropriate place to ask this question. I've had very little vhf/uhf experience and I am part of a team proposing a 2-way radio dispatch system at a University. The University is about 350acres and has many brick buildings. Some parts of the campus are also wooded. While I realize that no setup is 100% foolproof or perfect......I'm trying to decide on a Vhf or Uhf system. The "dispatch" center would be running about 25-40 watts into a vertical antenna mounted about 35 feet in the air. The "portable" radios' output is about 4-5 watts. Given the size of the campus and the setup I've described, can I expect a significant coverage/range difference between 155Mhz and 430Mhz?

[C138Kaysone]

But how good can VHF be? Doesnt VHF signals bounce unlike UHF?

[N_Jay]

Originally Posted by C138Kaysone

But how good can VHF be? Doesnt VHF signals bounce unlike UHF?

Yes, No, Maybe!

And that is definite!

Propagation is a funny thing. UHF will go through windows and doorways better, but VHF will go through walls better, but UHF bounces better, but VHF will go around corners better, but . . . . .

[C138Kaysone]

Originally Posted by N_Jay

Yes, No, Maybe!

And that is definite!

Propagation is a funny thing. UHF will go through windows and doorways better, but VHF will go through walls better, but UHF bounces better, but VHF will go around corners better, but . . . . .

I thought UHF was able to go through walls and penetrate through concrete.. which i dont know how or why.....

It would be nice to have em both work together but that cant happen.

[k4puf]

Thank you all for the helpful comments. I think getting on the campus and trying both VHF and UHF is in order.

[C138Kaysone]

Originally Posted by k4puf

Thank you all for the helpful comments. I think getting on the campus and trying both VHF and UHF is in order.

I think using UHF inside the building would be a good idea and all outside activities could go VHF, dont think it wouldnt be bad to have 2 repeaters set up and everyone would just walk around with two walkie talkies lol....

[Chauffeur6]

Originally Posted by C138Kaysone

I thought UHF was able to go through walls and penetrate through concrete.. which i dont know how or why.....

Originally Posted by C138Kaysone

I think using UHF inside the building would be a good idea and all outside activities could go VHF, dont think it wouldnt be bad to have 2 repeaters set up and everyone would just walk around with two walkie talkies lol....

Why are you giving advice if you clearly don't even know what you're talking about? You seem to give an awful lot of advice around here for a guy who doesn't even have a grasp of basic and fundamental radio concepts.

EDIT: I just realized this is not the first time people have made a comment like this towards you, so I guess you just don't get it and continue to post without having a clue. Is it true you failed your amateur radio license exam? No shock if it is, perhaps you should spend more time learning, and less time dishing out useless and incorrect advice.

[APTN]

Another thing to consider, what do your neighbors use ? (Is it possible that you may need to communicate with other entities in the area; Perhaps municipal, county, state governments, private entities, etc. ?) If so, you may want to get radios capable of doing so.

Example: UHF public safety radios in TN are often programmed with 460.4 mhz which is a statewide mutual-aid frequency. VHF radios may be programmed to operate on 155.37.

[rfradioconsult]

Remember the radio system designers credo. It's extremely difficult to get radio waves go where you want them to go; it is practically impossible to keep them from going where you don't want them to go.

[C138Kaysone]

Originally Posted by res6cue_dot_com

Why are you giving advice if you clearly don't even know what you're talking about? You seem to give an awful lot of advice around here for a guy who doesn't even have a grasp of basic and fundamental radio concepts.

EDIT: I just realized this is not the first time people have made a comment like this towards you, so I guess you just don't get it and continue to post without having a clue. Is it true you failed your amateur radio license exam? No shock if it is, perhaps you should spend more time learning, and less time dishing out useless and incorrect advice.

Ill just send you a pm of my long response, doesnt need to be posted here, its not bad...

[Chauffeur6]

Originally Posted by C138Kaysone

Ill just send you a pm of my long response, doesnt need to be posted here, its not bad...

So you send me a PM, then you either turn off PM's, don't clean out your full inbox, or block me so I can't reply?

[pachanga22]

Originally Posted by N_Jay

Yes, No, Maybe!

And that is definite!

Propagation is a funny thing. UHF will go through windows and doorways better, but VHF will go through walls better, but UHF bounces better, but VHF will go around corners better, but . . . . .

There you go with the definite word again---so how can you be so sure???

[RKG]

To the OP:

There's a bit of mis-information in this thread.

My advice to you is to retain the services of a qualified RF consultant. The fact of the matter is that, properly designed, either VHF or UHF frequencies can be made to work in the environment you have described.

[k4puf]

Thanks for the help everyone. We've retained an RF/Radio Communications consultant to try and get us setup probably with a UHF system. The campus where this will be installed apparently already has a lot of UHFinfastructure in place.