How far will it go - Range
Sometimes you just want to keep your pet in the car while you shop - and the range isn't important. Other times, you may be inside an arena or working on the 10th floor and wonder if the Heat Guardian can reach that far.
Almost all of the time the Heat Guardian will reach at least one city block. In a clearing it will reach about a mile.
There are a number of factors that affect how far a Heat Guardian can go. Imagine a straight line between the two antennas. The most important factors are:
1. Objects between the two antennas (on the straight line).
2. Type and orientation of the antenna
3. Power output
Objects between the two antennas
Solid objects act like slightly-translucent walls for radio waves - they can block a lot of radio. An 8" solid concrete wall, for example, will cut the range by 94%. Metal walls are bad, concrete are very bad, trees are not great...
So, what is between the two antennas matters a lot. Radio can ooze around objects, but it will still affect the range. Take a look at the next two images.
In the first image, I take a walk through Chapel Hill, NC with the base Heat Guardian in the back of my parked car and a mobile Heat Guardian (with attached GPS) in my hand. Much of the time the radio is shaking (because I'm walking) which will degrade reception. I stop every now and then to get a more stable reading.
The lowest signal level that can be received is about -135. The lowest signal level that can be measured is -128 (seriously).
The signal level is shown as labels on the points and the color tells how close to failure (red) they are. I stopped walking at .7 miles because the road was taking a serious down-hill bend and it was enough info - there was still a bar left, though.
You can see in the above image how buildings do reduce the range - but not to zero. Even in town the Heat Guardian goes about a block. Going straight down Cameron Ave. it easily reaches 0.7 miles. I was parked on the avenue going west and there were at least two cars parked behind me.
The below image is through a wooded area. Here the Heat Guardian barely reaches 0.4 miles.
Type and orientation of the antenna
Different-shaped antennas work different ways. Some get great range in only one direction while others get mediocre range but are omnidirectional.
The antenna shapes on the Heat Guardian are chosen deliberately.
The antenna on the base unit is called a dipole and it radiates like a huge roll of paper towel on the rod. Since the antenna sits vertically the radiation goes equally well in all X,Y directions but not so great up and down. As the base sits easily on a box it will work very well no matter where you are (as long as you're not flying through the air or in a well).
The loop antenna is custom to us, but it has some characteristics of a vertical antenna and some of a dipole. It radiates fairly omnidirectionally so if you don't have it exactly upright it still works pretty well. It is slightly directional with the loop - so it can be tuned for a bit more range if you have to.
The Heat Guardian supports two different power settings - high, and standard. The high value will go approximately 25% farther than the standard power but at the cost of battery life. More importantly: in high power mode you must have an antenna connected to the base unit or it may be damaged when transmitting.
The two images above were done at a power setting between high and standard (about 30% more than standard).