The easiest way to improve range is to add an efficient antenna to the receiver. An added advantage is that this raises no FCC or other regulatory issues. I have tested three styles of receiving antennas that lend themselves to DIY construction, the turnstile, Lindenblad and eggbeater. I find the latter to be the simplest to build and it appears to be a bit more efficient than the others.

Adding a wideband RF preamp between the antenna and receiver extends range even further. It is best to add the preamp at the antenna as this amplifies the signal but not any noise picked up by the coax cable. In cases where the antenna location might get too hot for the preamp, it can be mounted at the receiver with the disadvantage that it will amplify both the signal and the noise.

The wideband RF preamp board I designed, which offers more than 20dB gain in the 300-435MHz bands used by Home Automation and Security devices, is based on the Mini-Circuits MAR-6SM+ MMIC. It operates on 3.5V which needs to be fed from a higher potential through a bias resistor and optional RF choke. I have designed it to be powered over the coax with the bias resistor, choke and DC blocking capacitor located on the roZetta™ PCB (or within other receivers that may be used).

When even more range is required, wideband preamps can be cascaded although my design, being coax powered, only lends itself to being the last preamp in the cascade. The other preamp(s) need external power. The Ten-Tec 1001 kit is based on another Mini-Circuits MMIC and I have tested it cascaded with my preamp and also in a threesome with my preamp and another from Ramsey Electronics. (The Ten-Tec 1001 will fit within a Polycase LP11F enclosure if the corners of the board are notched.) Some superregenerative RF receivers cannot handle a strong input signal (the front-end RF amplifier gets overwhelmed) but I have experienced no problems with the Wen Shing receivers.

NOTE: A Google search will turn up other suppliers around the world for the Ten-Tec kit.

An example with two Ten-Tec preamps cascaded with one of my design is shown below.

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