433mhz micro directional antenna design

The problem with consumption is only marginally related to the antenna in this case. The only dependency is that with a better antenna you can decrease the error ratio, reducing the total amount of sent data. But if you want to reduce significantly the power, you have to play with the power management options of the transceiver, the chapter 5 of the manual.

Probably you have already read it and optimised the application, but if you want to sacrifice range and reduce power, the most obvious solution is to lower the transmit power, as described in section 5.5 (page 18).

The cantenna reduces only the power irradiated in other directions, but not the overall power irradiated; moreover, changing the antenna, yes, can affect the power consumed by varying the antenna impedance and lowering the power transferred, but you pay it with a loss in efficiency.

IMO the best thing to do is to optimise the radiation surface of the antenna and then reduce the transmit power to the working minimum.

Note that if you decrease the power too much, it may result in a high number of lost packets, and then in a higher consumption.

The modules you are using are only 0dBm (1mW) which is quite low power. The RFM12s that you are used to are normally 8dBm (6mW) and have a ready made, robust protocol. They are surface mount as well, so I'll assume you are using them mounted to a PCB.

My first thoughts would be to isolate RF issues from protocol issues. Set up a transmitter doing 101010101010 at whatever rate is required to transmit the data in your application. You seem to have a rate of about 2400Hz which is good for long distance without being so slow as to confuse any AGC in the receiver. Either use a scope on the receiver or set up something to detect this preamble like pattern, and see how far you can go with your current setup. This should make it possible to work out if it is an RF issue or a protocol one.

I don't know the HRR30 receiver, but most of the basic AM receivers have a non adjustable AGC in them. This means that it can be hard to work out exactly how long a preamble you need to bias the gain correctly, and also hard to work out what data rates are supported. Too short a preamble and the receiver will still be gained up and responding to noise. Too slow data rate and the gain will be all over the place. Your setup sounds fine, but may be worth investigating.

Bread boarding these transmitters and receivers is fraught with problems. I don't think that you need to resort to anything more than a quarter wave dipole though. Get the module onto a simple PCB and you will likely see a big improvement.

Another big assumption, but with projects like this it is often not worth implementing error correction. Just transmit several times and assume you will miss some packets. If that isn't acceptable, a send /ack system will be better then error correction.