You will probably get more responses if you describe what you want in
more detail: frequency of operation, inline or test instrument, self
contained or PC based, remote head, analog or digital display, cost,
commercial or homebrew etc.
;-) ANY ideas. ANY schematics, Any The topic is "direct reading" :-)

I haven't seen a lot of examples out there, but the project seems very
simple; perhaps trivially simple.

First, you build a directional coupler -- there are a number of designs out
there, but none are especially difficult. Then you rectify the voltage and
perhaps amplify it. Feed the two voltages into a microcontroller that does
the math and operates the display (digital of course). Analog isn't going
to be so popular because you not only need a meter (generally harder to get
and expensive these days), but you will need some custom meter face, and
what it needs to look like won't be all that obvious.

Another possibility along these lines would be a little more analog-ish.

Analog Devices makes a line of neat little "log amp" ICs. Feed them a
sample of RF on one pin, and you get out a DC voltage which is
proportional to the log of the RF voltage. They have a wide frequency
range and if I recall correctly the Vout=log(Vin) relationship holds
up pretty well over several decades of power level.

Build two direction couplers, as suggested above, but without the
rectifier diodes. The ARRL handbook has instructions for building
directional couplers for HF out of copper pipe. For a physically
smaller design (for lower power) google around for "stripline
directional coupler", "monimatch", and similar terms, or go to the
Boat Anchors Archive and hunt around for the manual for an old
Heathkit SWR meter.

Take the directionally-coupler-sampled RF signals (forward and
reverse) and run them into a pair of the ADC log-amps.

The two DC voltages which come out will be proportional to the
logarithms of the forward and reverse voltages. If I remember my math
correctly, this means that the difference of the two is proportional
to the logarithm of the ratio of the forward and reverse voltages,
and would thus be a pretty nice indication of the return loss in dB.
Zero voltage difference would mean zero return loss (infinitely high
SWR), and the voltage difference would increase with the return loss
(lower SWR). The upper limit on the voltage difference will probably
be set by the directionality limit of the directional couplers.

Take this voltage difference, run it through a voltage-to-current
converter (a.k.a. a series resistor) and into an analog meter, and
*bingo* you've got a direct-reading SWR meter. It'll read at the high
end of the scale for a 1:1 SWR and will not deflect if the SWR is
infinitely high.

It might need to be recalibrated for a proper full-scale deflection at
1:1 on any given frequency, to adjust for the directionality limits of
the couplers.

Take a look at the "DEM ABPM" (Down East Microwave All Band Power
Meter) at www.downeastmicrowave.com - it's a professionally kitted
version of a homebrew product, which uses one of the AD logamps for
frequencies from ultrasonic up through UHF, and a less-sensitive-but-
higher-frequency Linear Technologies part for frequencies from VHF
through microwave. Readout is through a common DC-to-LED-bargraph IC.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!