Antenna Questions to Reach Fort Worth Repeater, Base and Micro Mobile

[WSEL959]

Please forgive me if this is posted in the wrong forum. We're trying to figure out antennas to use a repeater. Our locations are 10 miles West, and 10 miles SE of the repeater.

With the West leg, we are trying to hit Haltom 725 with HT and Mobile. The repeater range is 10 miles, with an elevation of 650'. We have been able to transmit/receive with a Midland GXT67, Ch 22r, HiPwr, 1.25 miles South of this location. But we are unable to receive with Midland MTX 275 with the included 6" antenna or 3 DB Ghost. I'm thinking that if our 5w HT can transmit/receive, the 15w mobile should be able to do the same with 3 story buildings in the path.

For our SE leg, I have used a Midland MTX 575 (50w) with a Midland 32" 6 DB microwhip mounted at an elevation of 587'. Please know this antenna was temporary, for testing purposed only. I think (2) 75' trees are in the path. Unable to transmit/receive.

Is there a simple modeling software, or some other way to resolve these issues without aimlessly throwing money?

[Socalgmrs]

Ok so no amount of money will solve issues if things are in the way.   462.xxx MHz and uhf in general is extremely line of sight.  A 5w HT with a 771 antenna can do 1 mile or 50miles.  A20w base with a good antenna can do 1 mile to 200miles.  It’s all about line of sight.  Litterally if you can not see the repeater with binoculars or a telescope because of super heavy trees or buildings or hills you will not be able to hit it.   
 

with that said radio watts are not nearly as important as radiated watts.  Radiated watts starts with your radio, then coax and antenna.  A $450 woxoun 50w radio with bad cable and bad antenna may only radiate 60watts.  While a $120 20w radio with good coax and a good antenna may radiate  as much as 230w.     But none of that matters with out line of sight. Height mat or may not help.  There is no magic antenna or radio that will get around like of sight. 

[BoxCar]

2 minutes ago, Socalgmrs said:

Ok so no amount of money will solve issues if things are in the way.   462.xxx MHz and uhf in general is extremely line of sight.  A 5w HT with a 771 antenna can do 1 mile or 50miles.  A20w base with a good antenna can do 1 mile to 200miles.  It’s all about line of sight.  Litterally if you can not see the repeater with binoculars or a telescope because of super heavy trees or buildings or hills you will not be able to hit it.   
 

with that said radio watts are not nearly as important as radiated watts.  Radiated watts starts with your radio, then coax and antenna.  A $450 woxoun 50w radio with bad cable and bad antenna may only radiate 60watts.  While a $120 20w radio with good coax and a good antenna may radiate  as much as 230w.     But none of that matters with out line of sight. Height mat or may not help.  There is no magic antenna or radio that will get around like of sight. 

 l   Well, part of this is BS, but there are some parts that are correct. There are two paths that must be considered along with the radiated power of the target unit. There is a "talk out" path which is the repeater's coverage area. This depends on three things, antenna height, antenna type, and radiated power. This is also dependent on the terrain (more than obstructions) between the units. The other path is the return or "talk in" path. This path is also dependent on the same restrictions as the repeater. 

Obstructions do have an effect on the two paths, but their effect is more dependent on the type of obstruction and the density and - the total amount of obstructions. Trees, depending on the type, can interact with the signal. Leaves on trees such as the oaks Texas has in abundance have less effect than say a mesquite or pine. This is because the shape of the leaf can be seen as a mini antenna that acts as a receiver absorbing some of the signal. Buildings contain metal which blocks radio signals, and both the type and amount create problems. On the other hand, buildings and hard, dense ground like rocky cliffs can also be reflectors causing the signal to bounce in a different direction.

The power of the radiated signal doesn't increase distance as much as it fills the same area with more signal (signal density). The antenna determines how the signal is radiated. The most common is an omnidirectional having a doughnut shape around the center of the radiating element. How fat the doughnut is depends on the gain of the antenna. The higher the gain, the less "fat" shape of the pattern.

[Socalgmrs]

34 minutes ago, BoxCar said:

 l   Well, part of this is BS, but there are some parts that are correct. There are two paths that must be considered along with the radiated power of the target unit. There is a "talk out" path which is the repeater's coverage area. This depends on three things, antenna height, antenna type, and radiated power. This is also dependent on the terrain (more than obstructions) between the units. The other path is the return or "talk in" path. This path is also dependent on the same restrictions as the repeater. 

Obstructions do have an effect on the two paths, but their effect is more dependent on the type of obstruction and the density and - the total amount of obstructions. Trees, depending on the type, can interact with the signal. Leaves on trees such as the oaks Texas has in abundance have less effect than say a mesquite or pine. This is because the shape of the leaf can be seen as a mini antenna that acts as a receiver absorbing some of the signal. Buildings contain metal which blocks radio signals, and both the type and amount create problems. On the other hand, buildings and hard, dense ground like rocky cliffs can also be reflectors causing the signal to bounce in a different direction.

The power of the radiated signal doesn't increase distance as much as it fills the same area with more signal (signal density). The antenna determines how the signal is radiated. The most common is an omnidirectional having a doughnut shape around the center of the radiating element. How fat the doughnut is depends on the gain of the antenna. The higher the gain, the less "fat" shape of the pattern.

Of coarse radiated signal increases distance.  Take the same radio with the same coax and the same antenna hight but one is 3db and one is 12db.  That’s a difference of 100 miles line of sight.  You need to get out in the world and have experiences instead of books. 

[BoxCar]

7 minutes ago, Socalgmrs said:

Of coarse radiated signal increases distance.  Take the same radio with the same coax and the same antenna hight but one is 3db and one is 12db.  That’s a difference of 100 miles line of sight.  You need to get out in the world and have experiences instead of books. 

Radiated signal has very little effect on distance. You are increasing the signal density within the same area governed by the height of the antenna above the terrain level as dictated by the curvature of the earth. The distance to the horizon doesn't change no matter the power of the signal. Increased power primarily affects the area at the fringe of the coverage area making a marginal signal stronger.

[LeoG]

6 hours ago, WSEL959 said:

Is there a simple modeling software, or some other way to resolve these issues without aimlessly throwing money?

Kind of a pain because you have to register and there are tons of variables to set.  But it does a respectable job in predicting where the signal will be or not.

I suggest setting the reliability at least to 95% and I usually keep it at 98.5%.  Set the strong signal between 14 and 24dB

You can find your Rx threshold in your radio specs.  Mine says .25uV but I keep mine higher to keep things more realistic.  Currently I have mine at .316uV which is -117dBm.

High resolution is fine.  When you want to be critical you can use Very High Resolution.  But it takes substantially more time.

 

https://www.ve2dbe.com/rmonline_s.asp

[WSEL959]

On 11/1/2024 at 10:35 PM, LeoG said:

Kind of a pain because you have to register and there are tons of variables to set.  But it does a respectable job in predicting where the signal will be or not.

https://www.ve2dbe.com/rmonline_s.asp

Thanks guys.
LeoG, I think that is the information I am looking for. It may be beyond my understanding, but I want to take a stab at it none the less.

Would something like a directional yagi work, or is that just a concentrated line of sight?

Thanks again

[LeoG]

They have a selection for using a yagi antenna. They also have a section for you to program the lobes of the antenna but darned if I could get it to work.  So picking the yagi should give you a good enough example.