Simple RF Question

Discussion in 'Wireless & RF Design' started by davidGG, Aug 29, 2013.

  1. davidGG

    Thread Starter Member

    Dec 22, 2012
    Hello everybody,
    I am relatively new to RF electronics.
    I currently just completed an antennas course and it really got me curious about radio frequency.

    Here is my question:

    I want to purchase a RF generator just for hobby work. (i.e. propagation).
    What is the difference between something being labeled as a RF generator and an ordinary signal generator?

    As far as I know RF means the frequency of operation is in the radio spectrum. Other then that, are there any other differences?
    I understand that with the increase of frequency, electronic devices perform differently due to skin effects, impedance changes, and other properties of electromagnetism.
    If what I stated is not clear, what I mean is, is the output of the RF generator is the same type of current as a signal generator with the only difference being the range of frequency?

    The reason why I ask is because my antennas professor would always say that when using an RF signal, in order to match the impedance of an antenna you can not use resistors because of the properties of RF, instead you must narrow/widen the transmission line.
    However, I can not find any literature about this. I found a book on RF and there is an entire chapter that deals with resistors at high frequencies which is contradictory to what he said.

    I am totally confused. Maybe my professor was talking about narrowing/widening the transmission line once the wave is propagated and using that propagated wave as a proximity feed to an antenna?

    I tried asking him but he is from another country and didn't understand what I was trying to say so I just gave up. I hope you guys can clear things up.

    Sorry for the wall of text.
    I appreciate all of your help.
  2. #12


    Nov 30, 2010
    For the first answer, yes. A RF generator is a lot like an audio generator with a LOT higher frequency range. We have some people here that are really good with RF, but most of them are asleep now. Watch this space. You will have a conversation soon.
    davidGG likes this.
  3. davidGG

    Thread Starter Member

    Dec 22, 2012
    Thank You.
  4. davidGG

    Thread Starter Member

    Dec 22, 2012
    Any body ?
  5. bertus


    Apr 5, 2008

    A RF generator makes a signal with much higher frequencies as an audio generator.
    Also the output power will be limited.
    Most RF generators will have a maximum output of 4 dBm, wich is about 1 Vpp into 50 Ohms.

    You might also want to have a look at my RF related links thread:

    In there you will find all kind of links on all kinds of RF subjects.

    Last edited: Aug 31, 2013
  6. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    I think your professor is probably referring to the use of "tuned" transmission line segments to match source and load (e.g. antenna) impedances. The classical approach is to use a series transmission line segment between the load and a stub matching element, also made from a length of transmission line which may itself be "terminated" either with an open or short circuit. The target impedance seen by the source + feed line at the stub is typically the adopted system characteristic impedance - such as 50Ω, 75Ω etc.
  7. davidGG

    Thread Starter Member

    Dec 22, 2012
    Thanks for the link, Bertus.

    One last question. If I want to connect an antenna to a microcontroller and have it send out a digital signal (ie 0010010010) and have another antenna attached to a microcontroller wait for this signal. I would have to use a RF module as an intermediary between the antenna and microcontroller?
    Last edited: Aug 31, 2013
  8. WBahn


    Mar 31, 2012
    Depends on the microcontroller and the RF frequency you are talking about.