RF Self Study??Beginner please advice..

Hi,
I want to learn RF.
I ve some exposure in Analog circuit design/testing, based on op-amps,Mosfets,LEDs,sensors, & in microcontrollers & also some Power supply circuits like DC/DC converters.
I ve also experience in PCB design of 4 layers using Altium designer.(But Not in high speed).
So in order to study RF , i was thinking of doing some circuits by myself in my home itself.Since RF requires very high end devices for measuring & testing.I'm not sure about how to begin.

Can somebody suggest me some simple not so costly circuits to start with to prototype..
I do have a RF lab access with SA,VNAs etc as part of work but not for personal hobby circuits & Im involved in testing of some RF boards.So i can grab the terms and understand what they mean.But i want some hands on design experience. thats y im trying to do some circuits by myself.

Thanks for any help and advice.
regards,

i believe if you do a search in this forum, you will get lot of information as these questions are already answered.....

you can start from microstrip filter

A study starts with reading,not making some circuits blindly.
Read first then apply and read again...

1)I would start with a 915 MHz bipolar amplifier. Try to get at least 10 dB of gain out of it, a return loss of at least 8 dB at input and output.

2)Then move up to a FET amplifier at 2.4 Ghz--same parameters.

In doing those 2 projects you will cover all sorts of things--semicondcutor selection, biasing, impedance matching, gain and return loss testing.

Make sure you look at the outputs on a spectrum analyzer and if there are any unwanted oscillations at odd frequencies, hunt them down.

I would then do some filters, like

3) lumped element 200 mhz cuttoff 5 pole lowpass

4) lumped element 200 MHz highpass 5 pole

5) lumped element 200 MHz bandpass with 20 MHz 3dB bandwidth 3 pole

both of these will allow you to use chip components. How you breadboard the filters will determine if they work or not. You will also learn about Q. You will probably have to tune the circuits to get the frequencies just right. Are you getting the rejections and insertion loss you expected?

After that, try

6) 5 pole lowpass filter at 1 GHz on FR4 board with transmission line High/Low impedance elements.

After those, come back and tell us how you did.

Get hold of the AARL handbook (an old one will do?) American Amateur Radio League has a lot of basic RF theory. A RSGB handbook (UK version)
Frank

chuckey said:

Get hold of the AARL handbook (an old one will do?) American Amateur Radio League has a lot of basic RF theory. A RSGB handbook (UK version)
Frank

Click to expand...

I very much agree with chuckey. The ARRL handbooks are well-written from a practical level of RF design practitioner. For really getting into RF design, you'd next have to go to some college-level textbooks, starting with transistor-based amplifier design and lumped element filters. Following that, you could expand into the world of microwave theory and/or antenna theory.

---------- Post added at 14:59 ---------- Previous post was at 14:54 ----------

themaccabee said:

Hi,
I want to learn RF.
I ve some exposure in Analog circuit design/testing, based on op-amps,Mosfets,LEDs,sensors, & in microcontrollers & also some Power supply circuits like DC/DC converters.
I ve also experience in PCB design of 4 layers using Altium designer.(But Not in high speed).
So in order to study RF , i was thinking of doing some circuits by myself in my home itself.Since RF requires very high end devices for measuring & testing.I'm not sure about how to begin.

Can somebody suggest me some simple not so costly circuits to start with to prototype..
I do have a RF lab access with SA,VNAs etc as part of work but not for personal hobby circuits & Im involved in testing of some RF boards.So i can grab the terms and understand what they mean.But i want some hands on design experience. thats y im trying to do some circuits by myself.

Thanks for any help and advice.
regards,

Click to expand...

I'd start off by doing some reading into the fundamentals of RF design. On a regular basis, RF design techniques can cure issues/annoyances in low-frequency designs, but knowing the WHY is the only way to see where the issues come from. Blindly prototyping circuits without knowing about the fundamental and parasitic elements within each device/board could be a very long road to learning how/why things work at RF.

Thank you all
By the way why i asked for some circuits is that i may ve some focus on reading,since the area is so vast & im a novice.I'm not saying that reading is not important..But i would like very much to have a small aim ( say a circuit) and reading around those topics, then start prototyping.. and learn form it..

Thanks again for all ,, especially biff44,tony,chuckey,enjunear for giving me valuable directions..
Regards

themaccabee said:

Thank you all
By the way why i asked for some circuits is that i may ve some focus on reading,since the area is so vast & im a novice.I'm not saying that reading is not important..But i would like very much to have a small aim ( say a circuit) and reading around those topics, then start prototyping.. and learn form it..

Thanks again for all ,, especially biff44,tony,chuckey,enjunear for giving me valuable directions..
Regards

Click to expand...

Some of the circuits mentioned here would be good places to start. Lumped-element filters are pretty quick to understand... use a design template (most textbooks have low-pass/high-pass prototype circuits), calculate your component values, acquire parts, then fabricate & tweak the design (keep all of your RF parts CLOSE TOGETHER).

Following that, start with a simple class A amplifier... maybe grab a transistor with an Ft (freq of unity gain) around 100 MHz or lower. This will reduce your likelyhood of oscillation at high freqs while learning/playing with the design. The primary difference between transistor amp designs at low-freq and RF is that you need to isolate the RF portion of the circuit from the DC supplies, so instead of feeding the gate & drain with resistors, you need to use inductors (typically 100x the characteristic impedance of the system, generally Zo = 50 or 75 ohms). Set your bias point, calculate your load line, then work to match the input/output of the amplifier to your system's impedance (genrally 50 ohms for most test equipment and RF designs, 75 ohms for CATV/terrestrial radio systems).

In addition to the contributions from others, transmission line theory is important (inclusive Smith Chart). This is not only for cases where lines are no longer short w.r.t. wavelength, but also because transmission lines can be used to create inductors, capacitors, resonators, transformers, etc. You also need it to decide whether a lumped circuit approach or transmission line approach is required to solve problems.

In addition to knowing basic building blocks, you may also want to study receiver and transmitter topologies and noise in (telecom) systems.

Don't be afraid of "complex calculus". They had to give this another name as it makes problem solving in linear circuits much easier.

You have good instruments, so use them. When you are learning, making errors is no problem, as you will learn from them. Make sure you don't damage your instruments (for example by forgetting a DC block or reversing a bias circuit that directs DC to your instruments…).

thx u all i found what i find .