Sds100 and g5 type stub antenna

[radio3353]

But given equally resonant antennas, the longer one will pick up proportionately more signal. If the antenna's electrical length is 3.4" and its physical length is 1", it's picking up about 30% of the signal a full-length antenna would.

I got to thinking last night about the length of the Unication antenna. How do we know the element is only 1" long? That is just the length of the case. The element could be 3.4" or so in a coil which would make it a physical 1/4 wavelength antenna at 812 MHz. Maybe that explains its good performance (in addition to the radio itself being a well designed receiver.) Maybe it is a fractal antenna I'm sure it is nothing exotic though since it is only $14.95 bought on its own. Wish I still had access to an x-ray machine. And my specialty was not antenna engineering during my career. I did learn from the guys and gals in our antenna lab though that antenna engineering has a certain amount of black magic to it. Any antenna engineers here?

 

[radio3353]

On the g5's that we have changed out the oem with a specific 800mhz ant, we found that the 800 ant sometimes grabbed some noise from nearby electronics. Otherwise not much of a difference. We decided the oem is the best performer for the simulcast systems here. It is like the antenna high on simulcast.

A coworker who has trouble with other simulcast issues in the metro area, hooks his up to a simple collapsable / adjustable metal antenna mounted outside and gets very good results.

Yes, the whole is greater than the sum of its parts. We can't really just talk about the antenna in isolation. In a well-engineered system (antenna + radio circuitry all tuned together) the results can be stellar.

 

[jonwienke]

I got to thinking last night about the length of the Unication antenna. How do we know the element is only 1" long? That is just the length of the case. The element could be 3.4" or so in a coil which would make it a physical 1/4 wavelength antenna at 812 MHz.

No, that is how it is electrically 3.4" (using ~3.4" of wire wrapped into a coil), and therefore resonates at 800MHz insead of Wi-Fi freqs. The physical size is still 1", and as such is going to pick up about 5.3dB less signal than an antenna where the physical and electrical lengths are both 3.4" (i.e. the active element is not wrapped into a coil).

Also, any reduction in sensitivity to nearby noise sources directly correlates to reduced sensitivity to distant weak signal. The 5.3dB signal reduction that applies to nearby RFI applies equally to distant weak signals.

 

[jonwienke]

https://forums.radioreference.com/unication-forum/371951-g5-antenna-comparison.html#post2948768

The Unication stubby is more than 5.3dB worse than full-size antennas for the same band, including Unication and Motorola antennas. There is nothing magical about it.

 

[eorange]

Yes, the whole is greater than the sum of its parts. We can't really just talk about the antenna in isolation. In a well-engineered system (antenna + radio circuitry all tuned together) the results can be stellar.

Ding ding ding, we have a winner! This is the real answer. How else can the stellar reception and performance be explained?

 

[N6ML]

Some actual data, FWIW: https://forums.radioreference.com/unication-forum/371951-g5-antenna-comparison.html

Seems to backup Jon's 5.3dB theory (although this is signal strength, not SNR)

From a practical perspective, I've found the G5 with stock antenna to be quite impressive in terms of RF performance, and I really like the form-factor. I have lots of other gripes about the G5, though, and it is a band-specific radio...

 

[KR7CQ]

Some actual data, FWIW: https://forums.radioreference.com/unication-forum/371951-g5-antenna-comparison.html

Seems to backup Jon's 5.3dB theory (although this is signal strength, not SNR)

From a practical perspective, I've found the G5 with stock antenna to be quite impressive in terms of RF performance, and I really like the form-factor. I have lots of other gripes about the G5, though, and it is a band-specific radio...

In head to head testing with a Uniden beta tester standing next to me as a witness, less than an hour ago, I demonstrated that the G4 can pull in distant simulcasts (some VERY distant) with that stubby antenna that the SDS100 couldn't lock onto at all. I suspect a Motorola police radio would also pull in distant simulcasts with a stubby antenna.

There's an old radio guy saying that goes something like..."I'll take a cheap radio with a good antenna over a great radio with a lousy antenna". Oddly enough, the opposite can be true with handheld radios. A great handheld with a lousy antenna will outperform a handheld with issues with whatever duck antenna you want to screw on.

Say what you will about the Unication antenna, but their product, stubby antenna and all, works amazingly well, picking up simulcasts from 30+ miles away. Maybe when I see a scanner that can match that performance firsthand, I'll start worrying about antennas.

 

[vocoder]

Many can give a darn about the technical details & specs of why the g5 works with nothing swapped out or added. It just works. It works great on both types of simulcast and that means that its antenna is fine for the design.

I guess i am just going to have to go on a mission to find a short antenna to my liking that works good on my simulcast systems with my sds100.

 

[vocoder]

kr7cq, the simulcast that you compared is 30 miles away?

 

[KR7CQ]

Many can give a darn about the technical details & specs of why the g5 works with nothing swapped out or added. It just works. It works great on both types of simulcast and that means that its antenna is fine for the design.

I guess i am just going to have to go on a mission to find a short antenna to my liking that works good on my simulcast systems with my sds100.

If you want the best, pick up a Motorola full size 700 MHz duck antenna off of fleabay...then you just need the correct adapter setup. Adapter loss would be negligible. Then check the RSSI numbers for a difference. That's the same antenna used on pretty much all newer public safety handhelds now (that are for that band of course), so I think it's safe to say that it works about as good as a duck antenna is going to work. I picked one up for my G4 for like $15. If you truly want something shorter, there is the stubby Motorola antenna designed for lapel microphones...that would be the next step down in my view. Also, I've heard credible rumors that Unication may be offering such a creature for their units at some point in the near future.

 

[KR7CQ]

kr7cq, the simulcast that you compared is 30 miles away?

Yes, more than that actually. Picking up Mesa Arizona Topaz sites (not the secondary sites located closer to me) from my office in North Phoenix...the G4 had three bars, no signal for the SDS100 or the 436 I've tested.

 

[vocoder]

Yes, more than that actually. Picking up Mesa Arizona Topaz sites (not the secondary sites located closer to me) from my office in North Phoenix...the G4 had three bars, no signal for the SDS100 or the 436 I've tested.

I would post your findings here:

https://docs.google.com/spreadsheets/d/1pDX7yhQP03RC7yOzeAnkH530ux9hQcNpIirA4CnpS3M/edit?usp=sharing

 

[scannersnstuff]

The late great radio guy was Bill Cheek. Bill published scanner modification handbook's. The saying <citation needed> was something to the effect of "Give me a $10 radio, and a $100.00 antenna, and I'll play radio with the best of them. And I did". Cheek was a brilliant man. RIP.

 

[rcool101]

I use a Comet Miracle Baby and it works..Not so much in my basement or my boat 30 miles away. Outside and upstairs in the kitchen it works fine. Also in my truck around town. But I have a Radio Shack 800 that works better when needed

 

[jonwienke]

https://www.ebay.com/itm/SRH805S-BN...ge-144-430-1200MHz-radio-Antenna/281793246533

1/4 the price of the Miracle Baby. Performance is likely similar.

 

[Tim-B]

The link below is for a great 1/4 wave 800 MHz antenna that also works well on 700 MHz. I have several of them on various scanners. I have tested them in various areas to compare them to the radio shack/remtronix 800 MHz antenna and to compare them to the small stubbys that are linked to in previous posts. They are much better than the stubbys on 700 and 800 MHz but not quite as good as the RS/remtronix 1/2 wave 800 MHz antenna.

https://www.theantennafarm.com/catalog/laird-technologies-exc-806-sm-6923

 

[jonwienke]

Performance isn't the point of the stubby antennas, it's compactness and convenience.

 

[Tim-B]

Yeah, you're right. I guess what I was tryn'a say is that if they want smaller antennas that don't poke them in the armpits they can get these and have better reception than the stubby. They are about 3 1/2 inches long. Slightly more than half the size of the rs/remtronix but bigger than a stubby.

 

[rcool101]

https://www.ebay.com/itm/SRH805S-BN...ge-144-430-1200MHz-radio-Antenna/281793246533

1/4 the price of the Miracle Baby. Performance is likely similar.

Performance is likely? Then you don't have one...They Suck...I bought one ..waste of money.. Couldn't even get a signal anywhere

 

[jonwienke]

Performance is likely? Then you don't have one...They Suck...I bought one ..waste of money.. Couldn't even get a signal anywhere

Actually I bought two. Signal level is about 10dB less than the RH77CA on UHF, and 20dB less on VHF.

But that is good enough to get decent reception of my local county P25 system. As I expected, "good enough" to perform acceptably in strong-signal areas, but not something you would want to use to pick up distant signals.