433 MHz CC1000 Feasibility and Range

[cr0_]

cc1000 range

Hi,

I'm currently considering the feasibility of implementing a RF system to monitor cattle with the Chipcon CC1000 RF Transceiver, operating at 433 MHz.

The device will typically be attached around the necks of cattle, making it impossible to use an extruding antenna. What other types of antennas can I consider and what range in meters/kilometers can I expect?

Jacques

 

[boy]

cc1000 antenna

I think it is quite difficult. Radio wave will be blocked by cattle unless you have only a cattle in field. You may use planar antenna. We manage to fit it in 4x5 cm PCB. Maximum range may be less than 100 meters due to obstacle from other bovines. It depends on scenario. If bovines are in the field, it might be possible to reach 100 meter but if they are in confined space, e.g. daily cows, it might be difficult to obtain large distance.

 

[cr0_]

433mhz collar

The area to be covered is mostly open space. Typically I would like to get a range of 1000 meters between a tower and a cow, and a distance of approximately 2000 meters between towers (a square array of towers, each covering approximately pi*1000^2 square meters).

 

[FvM]

cc1000 distance

I think, at least several 100 m could be expected in free field, 1000 m is quite a lot for 10 mW, but not impossible. Using diversity receivers (several towers) is also a good idea. Using a matched rather than the usual short antenna can help to utilize the transmitter power as far as possible. A λ/2 dipole at the collar seems suitable to me. If a planar antenna (with a ground plane backside) is used, I guess it should be longer than 5 cm to achieve maximum efficiency.

Generally, some bands allow higher power than 433 ISM band, but the power supply is obviously limited with that application.

 

[cr0_]

cc1000 transceiver

Using a λ/2 wave dipole would be physically ideal in this situation. What I'm concerned about is the fact that water absorbs RF waves (and all organic things like humans and cattle are about 90% water).

Won't this significantly reduce the expected range? A λ/4 monopole antenna with a ground plane wont work in this situation, seeing that there may not be any extruding objects (antennas).

By law if I call correctly we may transmit up to 100mW here in South Africa without the need for a license. Are there easy (cheap) ways to amplify the output of the CC1000 or are there other suitable transceiver ICs better suited for this task?

 

[FvM]

cc1000 maximum range

I don't have a clear idea which part of transmitter power is absorbed, but I agree that it's should be considered as a problem. I'm rather sure, that a short would perform worse in most cases. But I also mentioned the option of long planar antenna. A collar with two integrated λ/2 strip line dipoles at each side may be solution. 100 mw can be achieved by an inexpensive one transistor PA, I think. With this power, the intended range sounds better.

 

[cr0_]

maximum range 433mhz

Would this type of antenna work?

**broken link removed**

How difficult is the PCB layout and matching of a single transistor PA to achieve 100mW output power?

 

[FvM]

cc1000

This antenna is very likely to work, but it's not suited for mounting at a collar cause it's to rigid, I think. Although I did some RF designs, including TI CC1050, I'm not a RF or particularly antenna specialist. Others may be able to suggest a suitable antenna design intuitively.

In germany, many farmers have short range transponders for their cattle for indentification and individual automated feeding in the cowshed. It's a small box hanging from a wide textil or leather collar. I imagine a similar design with antennas either integrated in the collar or fixed at the outer side.

The PA design is almost easy I think, PCB design for 433 MHz isn't really an issue.