Antenna Briefs #3 - Maximizing Range

This episode shows the factors involved in maximizing received power from a radio / wireless transmitter, and therefore how to maximize the transmission range. Examples of deep space links and terrestrial ( indoor / outdoor ) propagation paths are presented. Key equations are presented for the link budget, and for the antennas involved, including the relationship between antenna gain and effective area (aperture) of the antenna.

[@arttema950]

You videos are brilliant. Keep it up!

[@MegawattKS]

Thanks !

[@dominicestebanrice7460]

This series is fantastic! Thank you SO much for making this available. I've answered so many of the questions I had, and had several 'ah ha' moments in just a couple of hours watching and checking comprehension by working through some of the calculations.. Question please: you point out that one technique the Mars probe and its base stations use to compensate for the huge distance and the practical upper limit on transmit power on a satellite is by decreasing the bandwidth B - but how is that done? What are the variables that control bandwidth?

[@MegawattKS]

It's the bandwidth in the receiver. The receiver amplifies the signal, but also amplifies any noise that comes in as well. Antennas are generally too broadband to help (except for the one in the final episode of this series :-) ). But the receiver uses progressively narrower bandpass filters to pass the signal, but block as much noise as possible. Meaning, they narrow up the bandwidth before the demodulator to just the bandwidth required to pass the spectrum of the signal. In doing so, they eliminate as much noise as possible before making 'decisions' (like if a bit is a one or a zero). Technically, it's called "matched filtering", which is literally a complex (math) subject, but its really just this. I think the Voyager spacecraft has lowered its bitrate to something like 1 bit per second as it has left our solar system. The ground-based receivers have done the same thing (effectively using an FFT which is just a massive set of bandpass filtering operations :-) )

[@TheGameRRecon]

Following your advice, I'm following through with this video. With the power transmitted value, does/could this represent the power from the transponder? I'm planning on using the Space Deep Space Transponder from General Dynamics. Its input power is 19.5 W, is this the correct value to use? Its data sheet is available online. Thanks in advance.

[@user-rr6lb6bn1w]

Sir I used one tiny SA as signal transmitter to transmit rf signal at -7 dbm via a dipole antenna and another SA as spectrum analyzer connected also to a dipole antenna but even if i but the two antenna close to each other (1cm between) maximum signal strenth i can get is -27 dbm which i think it is very low since the two antenna seprated with only 1 cm and polarity is same you did same experiment in one of the videos before but you didnot show the value of the received signal could you please help explain why i have so much loss of signal althoug distance is very small and is it possible to contact you on mail or whattsapp or any other method if i need help in my project which iam working on now. If yes please support me with the most appropriate comunication method you prefer

[@MegawattKS]

I agree that sounds like too little signal received. At close range (

[@user-rr6lb6bn1w]

@@MegawattKS indeed it was very helpful. I pickedup my Nano VNA and checked out both transmitting and receiving antennas and found that one of them had issues so I replaced it with another. I checked again SWR for both antennas and found them between (1.1 : 1.25) which should be fine after that I took the measurment again with these antennas and found that signal strength improved up to -17 dbm (before it was -27dbm) at 1 cm distance between the Tx and Tr antennaswhich is the same you expected🙃. But I still find it strange to have 10 db signal loss in only 1 cm difference 🤔