Re: [loopantennas] Re: Active loop amplifier
> I understand that this requires proper analysis, but in my case the design
> is not only the wide dynamic range, but the deep null as well. From whatI've read
> so far, this requires the loop to be "ideally magnetic", i.e. insensitiveto the
> electrical field. This is achieved by using Alford loops, or reducing theamplifier
> input impedance, or both.response
> Reducing the input impedance requires high open-loop gain and flat phase
> of the amplifier. I think opamps can be better for this particularapplication
> (deep null), but again, detailed analysis is required.No, reducing the input impedance has absolutely nothing to do with high
open-loop gain. I achieve exceptionally low input impedances with
common-base amplifiers using a very simple technique that I patented:
"Common Base Amplifier Linearization Using Augmentation," RF Design,
October 1999, pp. 30-34.
"High Efficiency Broadband Linear Push-Pull Power Amplifiers Using
Linearity Augmentation," Proceedings of the 2002 International Symposium
on Circuits and Systems (ISCAS 2002), 28 May 2002, Phoenix, Arizona,
Vol. 2, pp. 432-435.
Common-Base Amplifiers with Linearity Augmentation, US Patent 6,271,721,
7 August 2001.
And it will outperform your monolithic devices any day of the week.
N7ZWY / WDX3HLB
Senior Member IEEE
- Hello Chris
With your experience should the board be Through Hole design or surface mount
Would the Through hole make a difference in RF ?
I checked quick and MPS6521SM seems not to be available but I did not spend too
I will go with through hole design for now since that would be the easiest to
make and provide as a kit .. for most.
From: Chris Trask <christrask@...>
To: firstname.lastname@example.org; email@example.com
Sent: Wed, June 30, 2010 8:41:26 AM
Subject: Re: [loopantennas] Active loop amplifier
>I'm in the process of designing an amplifier similar to this that should have
> I'm going to try and assemble something like this:
> Anybody tried a different amplifier for such loop? I've found a
> nice opamp from Intersil, EL2125 that has amazingly low voltage
> noise and enough bandwidth. Ordered samples today.
> Any experience here with this or similar parts?
better noise and IMD performance. The progress of this has been hampered by
other obligations. I'm using this project as a basis for the mechanical design
of shielded loops and Moebius Strip loops.
Avoid using opamps for active antenna design. Despite their low noise and
distortion specs, they still do not compare with those of discrete devices.
N7ZWY / WDX3HLB
Senior Member IEEE
[Non-text portions of this message have been removed]
> With your experience should the board be Through Hole design or surface
>I've used both. The transformers, connector, 47uF capacitor, and
transistors (plus a snall 10-turn pot used for R5) are all through hole.
Everything else is surface mount. There's little to be gained in the way of
board space going from a TO-92 to SOT-23 transistor package. There is,
however, much to be gained using 1206 capacitors and resistors. I did this
in order to get the best cost and performance. There is also a specific
need for this to fit inside an electrical conduit fitting, which is far
cheaper and stronger than an electrical utility box.
>Not for HF and below.
> Would the Through hole make a difference in RF ?
> I checked quick and MPS6521SM seems not to be available but I did not
> too much timeAnother reason for using through hole for that part.