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Type: Posts; User: volker@muehlhaus

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by volker@muehlhaus
Replies
3
Views
159

### Closed: Re: Need help for ADS equation reprentation...

In ADS help, search for function dbmtov()

That is function pow()

You can find a list of functions here:
Help > Simulation > Equations and Expressions > Measurement Expressions
2. ## Thread: Where to use this low gain and low profile Microstrip Patch Antenna?

by volker@muehlhaus
Replies
2
Views
193

### Closed: Re: Where to use this low gain and low profile Microstrip Patch Antenna?

Because directivity is low, or because radiation efficiency is poor (high losses)?
3. ## Thread: Place TX/RX Antenna?

by volker@muehlhaus
Replies
5
Views
291

### Closed: Re: Place TX/RX Antenna?

Network analyzer S21 measured from TX antenna to RX antenna

More distance between the antennas, possible anechoic absorbing material to reduce leakage, reduce near field reflections ... it...
4. ## Thread: Place TX/RX Antenna?

by volker@muehlhaus
Replies
5
Views
291

### Closed: Re: Place TX/RX Antenna?

Go and measure the coupling, instead of guessing.
5. ## Thread: how can I calculate the returnloss theoritically depending on the simulation results

by volker@muehlhaus
Replies
4
Views
465

### Closed: Re: how can I calculate the returnloss theoritically depending on the simulation resu

We have an expected range of values based on experience. For an accurate test, compare to measurement.
6. ## Thread: How to check recevied power in the HFSS port?

by volker@muehlhaus
Replies
1
Views
254

### Closed: Re: How to check recevied power in the HFSS port?

This sounds like the wrong workflow. Because of reciprocity, you can test the transmit case, which is much easier.
7. ## Thread: make a mismatching circuit

by volker@muehlhaus
Replies
13
Views
1,045

### Closed: Re: make a mismatching circuit

You need to work more carefully!!!

Now your TL2/MRSTRUB is an open circuit (hopefully) and you line can "see" the 540° long TL6 plus 900° (ninehundred degree) long line TL7, which transforms the...
8. ## Thread: How to design RF mixer

by volker@muehlhaus
Replies
3
Views
426

### Closed: Re: How to design RF mixer

Welcome to the lazy student forum.
9. ## Thread: make a mismatching circuit

by volker@muehlhaus
Replies
13
Views
1,045

### Closed: Re: make a mismatching circuit

C12 is a short at these frequencies, and TL2 transforms to an open at CTEE1.

If you want to have a DC feed at CTEE2, add a lamba/4 line (narrow, high impedance) and then the radial strub.
10. ## Thread: SMA-Microstrip transition removal for large-signal measurement of PA

by volker@muehlhaus
Replies
26
Views
1,325

### Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

Sure, but you misunderstood me. You need a matching circuit because the transistor side impedance is not 50 Ohm, and that is where your gap creates the extra inductance in the matching circuit PCB.
...

by volker@muehlhaus
Replies
3
Views
324

Makes no sense to me

That adds a lot of signal path loss (3dB from coupler etc) in front of the LNA, which means the noise figure goes up. I think your design with the separate LNAs first is...
12. ## Thread: SMA-Microstrip transition removal for large-signal measurement of PA

by volker@muehlhaus
Replies
26
Views
1,325

### Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

You can add a few nH in simulation and test it. The photo was for the matching circuit input, which is not a 50 Ohm environment. If it is low impedance, inductance matters more than for a high...
13. ## Thread: SMA-Microstrip transition removal for large-signal measurement of PA

by volker@muehlhaus
Replies
26
Views
1,325

### Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

Getting the reference planes is of course very important, so careful port extension might be required, depending on your port calibration method.

But what is also required is careful connection,...
14. ## Thread: SMA-Microstrip transition removal for large-signal measurement of PA

by volker@muehlhaus
Replies
26
Views
1,325

### Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

I also don't understand your concern. The large "non-RF-style" elements behind the radial stub are on the DC-side of things.

by volker@muehlhaus
Replies
1
Views
232

### Closed: Re: Dear all experts, I need your help for Agilent ADS 2015 libraries

This seems to be a special library or design kit.
16. ## Thread: SMA-Microstrip transition removal for large-signal measurement of PA

by volker@muehlhaus
Replies
26
Views
1,325

### Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

I think we're discussing different aspects here. Phase shift doesn't always mean change of impedance.

The impedance measured into the amp - as seen from the load side - moves around the Smith...
17. ## Thread: SMA-Microstrip transition removal for large-signal measurement of PA

by volker@muehlhaus
Replies
26
Views
1,325

### Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

I don't get your point here - you seem to have 50 Ohm lines with 50 Ohm source/load, so the extra length will not change impedances seen by the DUT.
18. ## Thread: SMA-Microstrip transition removal for large-signal measurement of PA

by volker@muehlhaus
Replies
26
Views
1,325

### Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

Short and direct connection from connector ground to microstrip (backside) ground. Your ground path with these connector (not designed for this side mounting) has too much length in the photo.

A...
19. ## Thread: SMA-Microstrip transition removal for large-signal measurement of PA

by volker@muehlhaus
Replies
26
Views
1,325

### Closed: Re: SMA-Microstrip transition removal for large-signal measurement of PA

Try to make a better (shorter) connection from SMA ground to the PCB ground. At the moment, you have a bit too much path length there. Parasitic ground path inductance is as bad as signal path...
20. ## Thread: Efficiency of four fed patch antenna

by volker@muehlhaus
Replies
4
Views
447

### Closed: Re: Efficiency of four fed patch antenna

My explanation: For simultaneous excitation, the transmission from 1 to 3 looks like port 3 reflection to the software. Then it is not "loss" for an efficiency calculation.

Why do you have 4 feeds...

by volker@muehlhaus
Replies
15
Views
1,297

### Closed: Re: ADS and S11 Equations for L & C

A frequency where the line can still be considered short, so that the curve is flat. For my RFIC component extraction with tiny dimensions, that low frequency could be 1GHz, but in other cases it...
22. ## Thread: Inductor question. Why current goes up then down instead of decreasing with frequency

by volker@muehlhaus
Replies
9
Views
496

### Closed: Re: Inductor question. Why current goes up then down instead of decreasing with frequ

I think it's MHz.

Your real world inductor has parasitic capacitances, which result in a rapid change of input impedance towards self resonance frequency.
Have a look here:...
23. ## Thread: Comparison of two antenna polar plots

by volker@muehlhaus
Replies
8
Views
568

### Closed: Re: Comparison of two antenna polar plots

Whatever is relevant for the application.

It seems that you start from an arbitrary result (call it solution) and now try to find a problem to fit your solution ... :roll:

by volker@muehlhaus
Replies
15
Views
1,297

### Closed: Re: ADS and S11 Equations for L & C

Many years of experience with extracting RLGC and circuit models from S-params :-D

Sure, you always get some numbers as a result, but these don't have a physical meaning (as a capacitance) at...

by volker@muehlhaus
Replies
13
Views
713

### Closed: Re: thought experiment to understand radio propagation.

Yes, think of a satellite, which covers a large area because it can "see" a large area.

Also think of radio towers for old TV (before satellite TV): they mount VHF/UHF antennas on high towers...
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