Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would
be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate
that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views.
It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if
you would like to post something on RF Cafe's
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: Adding two RF signals!!!
Wed Jun 01, 2005 6:03 am
Jun 01, 2005 5:57 am
I have two antiphase
Rf signals at 900MHz (not sinusoidal)...I wanna add them up. By doing
this actually I intend to cacel out the odd harmonics and add up even
Any suggestions out there !!!
have fun bye!
Wed Jun 01, 2005 11:46 am
From the description of the method
you suggest, you are not looking for a signal sumation but for some
sort of harmonic cancelation.
Because would it be a summation
the phase relationship of all harmonic would be the same.
Thu Jun 02, 2005 3:19 am
Thanks for the comments..
right..........what I want is a second harmonic, If I can.....
way is to do something like this. (with capacitors)...but this divides
the amplitude as well....
In + In-
Post subject: Adding two RF signals
Wed Jun 08, 2005 11:39 am
Unfortunately, you can't use passive
circuits to add voltages without loss.
You can only passively
add power in watts: 1Watt + 2 Watts <= 3 Watts for any kind of passive
Otherwise, adding 1V to 2v would give 3V, which gives
more power out than in: power for free - unless the signals aren't matched
impedance to begin with. And you don't get power for free.
Thu Jun 09, 2005 4:58 pm
I think you would want to actively
add the two signals. If they were at a low frequency, you would use
an op-amp, carefully adjust the input level of each signal to be the
same, and adjust the phase of one signal so the fundamental cancels
At RF, you might try to use a Gilbert cell active mixer
such as the Intersil HFA3101 or some other one with sufficient frequency
Post subject: Why not
Unread postPosted: Mon Jul 18, 2005 12:40 pm
you cannot use an op. amp. with a high bandwith? for example AD800¿1?
(I'm not sure) has 1GHz of bandwidth. Probably this a stupid question,
but I'm new in the RF.
Response to Cubeleg
Unread postPosted: Mon Jul 18, 2005 6:51 pm
When an opamp is rated at 1 GHz, the number is for the gain-bandwidth
product. An amplifier with a gain of 1 isn't particularly useful - a
1 GHz GBW opamp is really only starting to be useful as you go below