EMRFD Message Archive 11896

Message Date From Subject
11896 2015-11-17 21:57:10 mosaicmerc Getting into RF design
Hi all:
Just looking for some advice on getting into < 5W RF design from a TX/RX P.O.V. and understanding waveguides, impedance matching, VSWR as a means to measure the matching, etc. Also to get a better grip on handling harmonic EMI for EMC. While theory is great, I learn better by doing and measuring for feedback.

I made some investment recently into the area including a few texts, like a 2015 ARRL handbook , RF circuit Design by Bowick and The Essential Guide to RF & Wireless.

On the hardware side a few instruments, a Boonton 4210 RF microwattmeter and sensor, a DSA 815-TG SA. A couple mini circuits directional couplers, amplifiers and splitters good to 2Ghz. A leveled sinewave SG504 gen. good to 1ghz for scope cals. I have an analog Tek 2465A and a Rigol DS2302A good to around 300-350Mhz. A MASTECH LCR 5308 meter. Precision 6.5 & 5.5 digit bench DMMs and handheld Fluke 87V's. Rigol Arb wavefrom gen to 25Mhz. An RF signal gen from 35Mhz to 4.4Ghz. Low noise linear bench CV/CC supply.

All sorts of N, SMA &  BNC 50 ohm adapters, PCB launchers & bulkhead mounts, & pigtails. Two JFW rotary step attenuators (0-10, 0-70dB), a couple precision mini circuit fixed attenuator kits 1db to 30db.
Components: Assorted wideband/UHF bipolar transistors, varactors, trimmers, PIN diodes, GaAs switching FET, Schottky diode RF mixer/detector. Doublesided 1oz, FR4, PCBs down to 1/32" thick and flex pcbs for doing microstrip. Assorted toroid cores, several old 14" PC CRT monitors to 'scrap' for parts as well as a 27" Toshiba CRT TV. Lots of general 0805 SMD parts.

I want to integrate microcontrollers into my RF projects to send data, control tuning, and provide switching control etc. Maybe even do an automatic VSWR impedance matcher as a project. I use Microchip PICs.

I have a lot of 'work' ahead of me but any advice is appreciated, especially pitfalls to watch out for etc.
11897 2015-11-18 06:22:30 Graham / KE9H Re: Getting into RF design
Dear mosaicmerc:

Do you have a name?
Are you a licensed amateur radio operator?

You didn't mention EMRFD as one of the books you bought. (Experimental Methods in RF Design.)  This  email group is to discuss designs from or based on that book.

It focuses on RF design in the HF and low-mid VHF region.

You casually threw in the word waveguides.  That implies working with frequencies above 3 GHz. Which is a related but different world.

The simple answer to your request is to pick a receiver design and a transmitter design that interests you, from EMRFD, go build them and make them work. You will need an amateur radio license to legally put the transmitter on the air.  But, if you really want to lean microwave RF design, you might want to start somewhere else.

--- Graham


11898 2015-11-19 22:00:13 mosaicmerc Re: Getting into RF design
Thx for the input Graham.

As a relative RF noob, I appreciate the guidance.

I have a lot of work/study ahead of me.
I will acquire the book you mentioned. It's actually in my Amazon 'wish' list section.
I don't have the eqpt to do >3Ghz measurements such as a VNA....but first things first. Lower frequency competency development.
I am not in the U.S. /U.K. subject to all the regulatory issues. I am in the Caribbean.
11899 2015-11-20 14:33:41 Brooke Clarke Re: Getting into RF design
Hi Mosaic:

An analog sweeper, like the HP 8350B and a sensitive DC input scope, like the Tek 5110 series plus some components that cover your frequency range like a detector and directional coupler will get you a long way.  That's what I used when first starting out in microwave testing.  Later the company added Scalar Network Analyzers which was a big improvement on the grease pencil line on the scope.  If I was going to be doing swept component testing today that's what I'd get.

If you're going to be testing mixers, where the phase noise of the 8350B is a problem for measuring spurs, then a pair of synthesized signal generators and a spectrum analyzer may be needed.

When the 8410A Vector Network Analyzer came out I got one and wrote FORTRAN code to do S-Parameter analysis of circuits, like the microwave amplifiers that I designed or the existing problematical tunnel amplifiers that needed improvement for production.

Finally ended up building automated Microwave Test stations at first using HP Calculators, HP Rocky Mountain Basic then later National Instruments LabVIEW.