How to increase range (antenna?) for RF Wireless Modules

I have a pair of these:

Two RF Wireless modules with the USB converter and the two antennas and I managed to make them work. I have the one connected to the Arduino and the other on a laptop and I'm getting some measures to the laptop. The Arduino is inside a small metal building. When I am in a range of 80-100 meters around of this metal building with the laptop on my hands and the module on it, I have good connection. However if I go a little bit far from this range I lose connection. I want to succeed a bigger range so the laptop to be in a distance of about 450 meters from this building in an office.

How can I do this? Can I search for a longer/bigger antenna or something? And if a longer antenna will work, what type is the best to use?

Working frequency of these RF wireless modules is 431~478Mhz and I use 433Mhz
Also, the manufacturer says 1km range. Probably they're talking about straight-no wall communication

For example here are some antennas, will any of these do my job?

Also, is it wrong that I have the antenna inside the building? Do I have to install it somehow outside of this building so to be out in the air? I have it near an open window, but maybe I have to install it outside?

or what about this?

I think these modules are similar to the ones I the antennas need to be 50 Ohm....433mhz is in the 70cm wave length region..

Look for an antenna with a high gain for this I mean db e.g 12db gain.....Yagi antenna have great gain but are directional, the RF is concentrated in a given direction.. as opposed to omni directional.... all directions

There are 2 measurements of RF power..feed power and ERP (effective radiated power).

Feed power is what is fed into the antenna, ERP is what comes out the antenna...

If you feed in 100mw (milli watts) of power into a 12db antenna, every 3db doubles the ERP...

So....100mw to 200mw (first 3db of 12db)..200mw to 400mw (2nd 3db of 12db) ..400mw to 800mw (3rd 3db of 12db) and finally ....800mw to 1.6watts for the final 3db of 12db....3db+3db+3db+3db=12db

This is grossly simplified....but is a guide :slight_smile:



If you are looking for 12db of omni directional gain at 433 Mhz, then the antenna will be huge , basically a very tall collinear array.
Heres an example.
This antenna has only 6 db gain and its over a metre long, so to get 12 db you would be looking at over 4 meters in length.

There is no line of sight between the two places. There are many trees and two buildings that probably obstruct the signal.

Question, if I install two antennas like this in the link:

one in the arduino module and one in the laptop module and install them on the roof tops or put them high with a mast and connect them with cable to the modules, could it work?

I'm looking forward for your opinions.

Depends on what type and length of cable you use. You could easily have more loss in the cable than gain from the antenna.

I just ran a Yagi through my optimizer program and you will need 13 elements on a 2.95 wave boom(80") to get 15.11dBi(12.97dBd) gain. That would require a feedline of very low loss to get 12dBd, or the Arduino and radio mounted at the feedpoint with an RS-485 link to the PC.


Coaxial cable is the cable I must use as far as I know. Length I don't know, but it's ~5 meters to the rooftop and let's say 3 meters inside, let's say 8 meters total. How loss will I have and how will it affect my data?

In general, if the cable is small then it's lossy. Here's a link to some attenuation data.

If you've not worked with UHF antennas and coaxial cable then you should consider a commercial setup.

Here’s another chart. Note that the same cable and length on one chart does not necessarily agree with another. It depends on who measured the loss, who made the cable, and the test procedure.

Attached is the result of the 13 element Yagi. The dimensions are in waves and can be converted to lengths for any particular frequency.

hm, so what's your opinion?
install two antennas like this: Diamond Antenna X-30 (VHF/UHF), FREEBYTES
on roof and connect them with coaxial or install yagi? Since I do not know much about yagi antennas, do I have to use yagi in both modules and also do the yagis need to face each other (los) or no?

That antenna will not do the job if you need more than 5.5dB(probably dBi). If your cable has only 3dB of loss then you will lose half of your radiated power, half of your received signal, and an increased the noise level. That antenna has a pattern lower on the horizon than a simple 1/4 wave vertical but still works in all compass directions. You will need two directive antennas aimed at each other and low loss coax. You may be able to use directive antennas at a lower level and take advantage of a common reflective surface seen by both stations.

I found this directional yagi antenna:
As i see it works for my frequencies. So, buy two of them and install them with good quality cable to the modules? And also, do I have to install them on the roofs or I can install them lower, under the hight of the obstacles (trees, two buildings)?

A pair of those will work although the gain over a dipole is 11dB. Manufacturers like to use dBi because it's 2.14 higher and looks better in ads. An isotropic radiator, 0 dBi, only exists in equations. A simple dipole is a better reference because they're made easily and have directivity in it's own axial plane.

If you use about 8m of RG-8X, easy to work with, you will have about 2/3 of your module power reaching the antenna. You will lose some signal coming down but still have the equivalent of about 9dBd available. You will also need some cable adapters to go from N/SMA or PL259/SMA. The PL259 is not as well matched to 50R as the N connector but it's much easier to work with. Find a local ham radio operator to help.

You can mount the antennas directly at the top of a pole with the elements horizontal. The photo shows vertical but that's for ham repeaters. You do not have to get above the trees, only the building line of sight ahead of you. If you're in a humid climate then change the hardware, nuts/bolt/clamps, to stainless steel.