Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes Calculators Education Engineering Magazine Articles Engineering software RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Forums Magazine Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Anritsu Alliance Test Equipment Amplifier Solutions Anatech Electronics Axiom Test Equipment Berkeley Nucleonics Bittele Centric RF Conduct RF Copper Mountain Technologies Empower RF everything RF Exodus Advanced Communications Innovative Power Products ISOTEC KR Filters Lotus Systems PCB Directory Rigol RF Superstore San Francisco Circuits Reactel RFCT TotalTemp Technologies Triad RF Systems Windfreak Technologies Withwave LadyBug Technologies Wireless Telecom Group Sponsorship Rates RF Cafe Software Resources Vintage Magazines Thank you for visiting RF Cafe!
Triad RF Systems Amplifiers - RF Cafe

Power delivered to antennae - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2010 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2010, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. Regardless, there are still lots of great posts in the archive that ware worth looking at. Below are the old forum threads, including responses to the original posts.

NOTICE: The original RF Cafe Forum is available again for reading, and the new RF Cafe Blog is an active board.

-- Amateur Radio

-- Anecdotes, Gripes, & Humor

-- Antennas

-- CAE, CAD, & Software

-- Circuits & Components

-- Employment & Interviews

-- Miscellany

-- Swap Shop

-- Systems

-- Test & Measurement

-- Webmaster

darcyrandall2004

Post subject: Power delivered to antennae Posted: Fri Mar 09, 2007 11:32 pm

Colonel

Joined: Tue Feb 27, 2007 6:16 am

Posts: 46

Hello. I am designing a UHF transmitter. I wish to be able to determine the requirements of components on the output stage, after the amplifier and the power delivered to the antennae.

To begin with I am analyzing the application note designed for 380MHz. My final design will be for 450MHz

The RF2175 datasheet claims that the amp delivers 31.8dBm Linear Output Power.

The figure below shows the output stage and where I have attempted to calculate the current in the branches.

BELOW IS THE MATLAB CODE I USED TO CALCULATE THE CURRENTS IN THE BRANCHES, COMPONENT RATINGS AND THE MAXIMUM POWER DELIVERED TO THE ANTENNAE.

format long

clear

f=380000000;

wo=2*pi*f*i;

%DETERMINE THE RF2175 AMP'S OUTPUT POWER IN WATTS

pout=(10^(31.8/10))*10^-3;

%THE CALCULATED RF2175 OUTPUT IMPEDANCE (THE CONJUGATE OF THE LOAD)

rf2175_z=1.83712875712576 + 7.16437870763534i

%CALCULATE THE THEVENIN VOLTAGE, P=v^2/r, pout=v^2/(2*real(rf2175_z))

v=sqrt(pout*2*real(rf2175_z))

%CALCULATE THE IMPEDANCES OF COMPONENTS AT 380MHZ

XC9=1/(wo*56*10^-12);

XL1=wo*3.6*10^-9;

XC10=1/(wo*12*10^-12);

XC11=1/(10^-9*wo);

XL6=wo*12.55*10^-9;

%CALCULATE THE BRANCH CURRENTS

I(1,:)=[rf2175_z+XL6,-XL6,0,0,-v];

I(2,:)=[-XL6,XL6+XC9,-XC9,0,0];

I(3,:)=[0,-XC9,XC9+XL1+XC10,-XC10,0];

I(4,:)=[0,0,-XC10,XC10+XC11+50,0];

I=rref(I);

I1=I(1,5);

I2=I(2,5);

I3=I(3,5);

I4=I(4,5);

sprintf('CURRENT RATING FOR L6')

[mag,theta]=cart2pol(real(I1-I2),imag(I1-I2));

mag

sprintf('VOLTAGE RATING FOR C9')

[mag,theta]=cart2pol(real((I2-I3)*XC9),imag((I2-I3)*XC9));

mag

sprintf('CURRENT RATING FOR L1')

[mag,theta]=cart2pol(real(I3),imag(I3));

mag

sprintf('VOLTAGE RATING FOR C10')

[mag,theta]=cart2pol(real((I3-I4)*XC10),imag((I3-I4)*XC10));

mag

sprintf('VOLTAGE RATING FOR C11')

[mag,theta]=cart2pol(real(I4*XC11),imag(I4*XC11));

mag

sprintf('POWER DELIVERED TO 50 OHM ANTENNAE')

real(I4*I4*50)

BELOW IS THE RESULTS PRODUCED

rf2175_z =

1.83712875712576 + 7.16437870763534i

v =

2.35822259134855

ans =

CURRENT RATING FOR L6

mag =

0.25101690661180 Amps

ans =

VOLTAGE RATING FOR C9

mag =

1.82181323340670 Volts

ans =

CURRENT RATING FOR L1

mag =

2.56132106649834 Amps

ans =

VOLTAGE RATING FOR C10

mag =

1.59717311590861 Volts

ans =

VOLTAGE RATING FOR C11

mag =

0.03475316915436 Volts

ans =

POWER DELIVERED TO 50 OHM ANTENNAE

ans =

-0.75495330687175 Watts

»

I understand that the current rating for L6 would be determined by the dc bias current it supplies.

Do these other calculations look correct?

When the data sheet states that the amp has 31.8dBm output power, does this mean that if the load is a conjugate of the output impedance, 31.8dbm will be delieverd to the load? Or is half of this value disspiated in the output impedance of the amp?

Thankyou

Cheers

Top

darcyrandall2004

Post subject: Posted: Mon Mar 12, 2007 11:19 pm

Colonel

Joined: Tue Feb 27, 2007 6:16 am

Posts: 46

Not sure why your image isn't appearing. Let's try this:

(Kirt Blattenberger 3/13/2007)

Posted  11/12/2012

RF Superstore (RF Components) - RF Cafe
RIGOL Technologies (test equipment) - RF Cafe
TotalTemp Technologies (Thermal Platforms) - RF Cafe
Exodus Advanced Communications Best in Class RF Amplifier SSPAs
everythingRF RF & Microwave Parts Database - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

These Are Available for Free

 

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024

Webmaster:

    Kirt Blattenberger,

    BSEE - KB3UON

RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:

AirplanesAndRockets.com