Stico Design Questions

[KD4CSO]

I bought a dual-band (VHF/UHF) disguise fender mount antenna from Stico for my 2018 F150 Lariat Diesel. Just 'cause, you know, one more antenna is always good.

I'm trying to understand Stico's design philosophy.

The way my mind thinks, after the antenna impedance match cable, I'd split and low-pass the AM-FM "pleasure radio", and send that cable to the radio. They I'd send the (combined) hi-passed 150 MHz-up VHF/UHF two-way cable to the back, and split/bandpass that into VHF/UHF short antenna leads that would plug into those two radios.

What Stico did, after the impedance match cable, was split using a "dual band coupler box" into a UHF feedline and an interconnect cable that goes to another splitter which separates out an AM-FM cable for the pleasure radio, and a feedline for the 150-174 MHz VHF two-way. So in the typical "two-way radios in the trunk" installation you've got two runs of coax (instead of just one) from the dashboard.

I suppose their setup would be useful if the customer was using a VHF Convertacom/ ASVA under the dash... but I'm thinking more customers would have the radio decks in the trunk.

Thanks for anybody who has any insight into this.

Those splitters and coax do sort of "crowd up" the inside of my dashboard. Not that I was planning to run power/ data for another front-mounted radio or anything...

Arthur

 

[W9WSS]

Arthur, I will tell you this much; I've had numerous NMO non-disguise style antennas on my work and POV's, and have had excellent performance with them. One or two of my undercover department-issued cars, I had a Stico or two. We had performance issues using the Stico and ended up going back to a quarter-wave on an NMO mount.

Lately, after speaking with an installer, he informed me that in their recent installations using Stico and other disguise-style antennas, they ended up running a separate AM/FM broadcast radio antenna, generally an adhesive-backed wire up and around either the front or rear windshield. The Stico separator/combiner that is supposed to connect to the broadcast radio was inferior, hence, the disguised wire mounted inside the windshield.

It would be interesting to see what performance others have had with Stico disguise antennas on scanning receivers also.

 

[prcguy]

I would also expect AM reception to suck with a disguise antenna wiht all the 50 ohm components in the line. A typical AM/FM antenna is several thousand ohms impedance on the AM broadcast band and high impedance coax is used all the way to the radio. This high impedance coax works fine for FM broadcast and is a must for good AM reception.

Now take the short vertical disguise whip antenna, which can work fine for AM/FM broadcast and whatever VHF/UHF bands its tuned for and feed it with lots of 50 ohm coax and run it through 50 ohm filters to separate the bands and an AM broadcast signals arriving at the antenna will be snuffed out by the coax and components that are 50X or more lower in impedance than the antenna feedpoint on AM broadcast.

I would also recommend sticking with the original AM/FM antenna whenever possible if you are using an AM/FM disguise antenna.

 

[kb4mdz]

Well, did it come with instructions? I checked the Stico site, and found instruction sheet #ci-239, for all dual band VHF/UHF antennas; it shows a dual band coupler box to split UHF from VHF & Broadcast, and then an AM/FM Broadcast coupler in the VHF line, and 17 ft RF cables from that coupler and the VHF/UHF splitter.

Maybe it's coupler box/engineering/cost decision; If you're doing just AM/FM/VHF box, that's simple. And the quicker way to add UHF is to do what you have. Maybe trying to do one box that splits AM/FM Broadcast, VHF and UHF all out of one is more expensive design and built.

Just postulating.

 

[KD4CSO]

Thanks for all replies. I've used various Sticos over the years (in sedans mainly...a few Fusions and a Caprice) and never had any real performance issues with them. (Other than them not being in the dead center of the roof, of course...) I was pleased that my F150 came with a real AM/FM whip antenna on the cowl, and not one of those shortie shark fin things... and the Stico is at least as long as the Ford whip. The Stico looks like it's somewhere between 3/8 and 1/2-wavelength on VHF high... Anecdotally, it receives a local FM better (quieter, with few dropouts) inside our underground garage than the Ford whip did... and it receives WBZ-AM's HD without fading (Boston's about 500 miles from here). So there doesn't seem to be much tradeoff on the AM/FM side of things. Again anecdotally, (I haven't done any measurements and have only had the antenna up for about a week), it seems a bit weaker (slightly noisier) on VHF (NFM) and about the same on UHF (450 MHz WFM).