Vintage Radion UHF Indoor Loop Antenna

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#1
Here is the vintage UHF loop I was talking about that uses a wide surface area loop. Ive been bidding on these for the last year, but always the bridesmaid, never the bride.






Channel Master also had something similar...

 
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JER

DTVUSA Member
#6
Its been known for long time that thick elements have wider bandwidth than thin elements. The developers of the Radion and Channel Master antennas were apparently trying to take advantage of that concept.

I was not aware of either of these elements until the photos were posted here by EV. They look remarkably similar to the first thick wide flat loop element that I prototyped early in the Clearstream development process. You can see a photo of mine in a paper I presented to the SBE in Pittsburgh last year. The paper is on my website if you're interested.

In the case of the Clearstream antennas we were aiming for a very compact loop - reflector combo with good gain and VSWR across the post 2009 UHF band. In my research, I discovered that element thickness only tells part of the story and I ultimately found the tapered loop element to be better than loops that were uniformly thick like the one above.

The thing surprises me the most is that these photos show that the thick element concept was known and used early on in television. Yet, the vast majority of the modern indoor loop elements that I've seen are made with thin wires and employ manually controlled tuning networks to peak signal on one or a few channels rather than trying to receive the whole band at once. The manual adjustments and narrow tuneable bandwidth haven't made any sense to me since the introduction of the remote control. Its been a mystery to me how such antennas could be sold to people that didn't want to get out of the easy chair to adjust the antenna every time they changed channels when a simple wide thick element would have eliminated most of that hassle.

Looking back, I suppose the other advantage with the early generation receivers may have been that the tuneable loops might have acted as a pre-selector to improve performance. The preselector idea can still be an advantage today, but the convenience of the remote control and channel surfing generally should take first priority in the design.

A tuneable bandwidth antenna that is compatible with channel surfing can be realised using smart antenna technology. I have designed and demonstrated such antennas but the market is not quite ready yet since most TV's don't yet have a smart antenna interface.

As a final note, I don't think the existence of the Radion element detracts from or otherwise invalidates the innovations in the Clearstream antennas. Had the notion of the optimised compact tapered loop - reflector combination been obvious then it wouldn't have taken until now to see such items available in the market place!
 

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#7
Thanks for sharing your knowledgable thoughts JER.

I wasnt implying that the ClearStream antennas werent innovative. I just wanted you to see, as a FYI, that the wide surface area loop was available in vintage designs...though they faded from the marketplace.
 

JER

DTVUSA Member
#8
Thanks again EV!

It was surprising to me to see that thick elements were used early on and then abandoned despite what, on the surface at least, appears to be a compelling advantage.

It would be interesting to be able to go back in time and learn what drove the various manufacturers to abandon them in favour of the thin loops with manually adjusted peaking circuits. Was it a case of cost, performance, aesthetics or simply marketing? One thing to consider might be that the vast majority of signals in the old days were VHF so perhaps the big thick UHF loop didn't add enough value for consumers despite its improved technical merits? Maybe it had something to do with UHF receivers of the day and the extra selectivity of the thin loops helped? Maybe it was all marketing? We'll probably never really know at this point!

One thing I've had pounded into my head is that consumer product design is never just about technical merit. The other factors always play a role, and that role is often just as big or bigger than the technical issues. That's why its always good to go back and revisit old ideas and make sure that the decisions still make sense in light of new information, requirements, and markets. If you look carefully you'll sometimes find an opening to do something new and innovative.
 

Piggie

Super Moderator
#9
Its been known for long time that thick elements have wider bandwidth than thin elements. The developers of the Radion and Channel Master antennas were apparently trying to take advantage of that concept.

The thing surprises me the most is that these photos show that the thick element concept was known and used early on in television. Yet, the vast majority of the modern indoor loop elements that I've seen are made with thin wires and employ manually controlled tuning networks to peak signal on one or a few channels rather than trying to receive the whole band at once. The manual adjustments and narrow tuneable bandwidth haven't made any sense to me since the introduction of the remote control. Its been a mystery to me how such antennas could be sold to people that didn't want to get out of the easy chair to adjust the antenna every time they changed channels when a simple wide thick element would have eliminated most of that hassle.

Looking back, I suppose the other advantage with the early generation receivers may have been that the tuneable loops might have acted as a pre-selector to improve performance. The preselector idea can still be an advantage today, but the convenience of the remote control and channel surfing generally should take first priority in the design.
JER, I bet they died out because they were gaudy (or read that ugly). Or a simple loop took a lot less material.

The early UHF tuners were like barn doors on selectivity, but then there were very few UHF stations, maybe one per town, at least from when I was a kid in Florida. UHF didn't take off until the 1970s.

People in the 1950's and 60's were as wowwed by technology advances as you find people today. Probably more so than the era between. It was the era of the future with helicopters instead of cars. Going to Jupiter or the stars by now. So I think someone said hey, lets put a tuned circuit in the UHF antennas since the band is soooooo wide (14-83). Plus I remember people buying them and some where all into the knob, other's had no idea what to do with it. I remember showing my aunt in the early 60's to pick up WSUN on 38 in Tampa to tune the knob to a certain letter on her antenna.

I the knobs to tune soon disappeared, and UHF tuners were more stable, hence they could use a narrower IF and way more sensitive. So they really were no longer "needed".

Back when they were popular, all the TVs I used you got up out of your chair to change channels. A concept brought back by the Wii. A display device that makes you move, lol.

Is this any more strange than the early use of the Gray-Hoverman antenna to see it fade out and reappear? I am not saying you used these idea to do the CS, but you did come across the same basic again. I have seen this in my wife's jewelry over and over. She will come up with a new design and before she can post it on the net, some else does the same thing.

There is something in the human psyche where similar ideas (and mistakes arise at the same time or often again generations later).

Wheels keep on turning, going round and round...
 

EscapeVelocity

Moderator, , Webmaster of EV's Antenna Blog
#10
Maybe it had something to do with UHF receivers of the day and the extra selectivity of the thin loops helped?
I think maybe this had a lot to do with it. Piggie was talking about it as well.

If you look at design over time from the 50's to the 60's and 70's you will see a lot of fancy designs with multiple loops and whatnot. I dont think it was cost that was driving the abandonment of these flat metal loops.

Although brass was pretty much abandoned, at some point in the late 70s and 80s.


Personally, I think the sleek lines of the Radion are aesthetically pleasing. It also has a "Space Age-ness" about it.

I like the Radion much better aesthetically than the Channel Master version.

Remember the radon scare?
 
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BCF68

DTVUSA Member
#11
Thanks again EV!

It was surprising to me to see that thick elements were used early on and then abandoned despite what, on the surface at least, appears to be a compelling advantage.

It would be interesting to be able to go back in time and learn what drove the various manufacturers to abandon them in favour of the thin loops with manually adjusted peaking circuits. Was it a case of cost, performance, aesthetics or simply marketing?
I would imagine it was much cheaper to make a loop antenna out of a wire than to thick elements. Which means they could be sold cheaper which in turn means more sales.
 
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