What is the best module for data transmission in wooded areas?

[DGraham]

Hello, I'm currently working on a project in which we need to send data periodically (approximately once every 1 to 5 minutes) through a heavily wooded area with as little power as possible. My research suggests that RF in the sub-GHz range would be the best for areas with lots of obstructions (trees and rocks). The constraints of this project don't allow for a large external antenna on either the receiver or the transmitter. I also don't have the ability to mount any transmitting/receiving antennas at any height greater than 4-6ft off the ground. I'm also looking for something in the 4x4mm range for package size.

Does anybody have any suggestions on something that could fit this bill? Thanks.

[Petter Myhre]

What range do you require?

[Josh Grob]

Also, what is the environment like in the wooded area? Presence of a lot of water does cause more interference in the 2.4Ghz bands vs sub 1Ghz. Having said that there is a good bluetooth router on the market with beefed up antennae arrays that can extend BLE quite far (1000ft or so).

[DGraham]

I appreciate the responses. I need to transmit data at least 100ft, although any added range would be a benefit. I'm limited on the transmitter power but not so much for the receiver. The goal is to be mobile, so a bluetooth router doesn't seem ideal.

[Petter Myhre]

We have som sub-GHz ICs, but these are old designs.

100 ft should be achievable with our newer ICs, nRF51 and nRF52, but it depends on a lot of factors; RF design, output power, RX sensitivity, data rate. The best way to know is to buy two DKs and test.

4x4mm is very small. The smallest package we have is the nRF52 in a WLCSP package, it is 3x3.2, this is of course without any of the external components; crystal, antenna, and so on.