2.6 GHz patch antenna for CMDA 800/1900 MHz?

[ezlynx]

I hooked up a Novatel Ovation MC760 requiring a 800/1900 MHz signal to an old 2.6 GHz patch antenna (2500-2700 MHz) out of desperation when the MC760 signal strength degraded significantly (degraded signal for a week). I did not have much hope because the antenna used a different bandwidth.

I was happy to find my signal improved significantly (no more banging head against wall and waiting for pages to load). Somewhere around a 15 dBm improvement.

Is it unusual or is it to be expected that an antenna designed for a specific bandwidth will improve a different range of signal?

 

[kspalla]

Patch is directional antenna. so there will be more gain. but coverage area gets lower.
I do not see problems if lower band bandwidth gets transferred to high band by means of converters (up/down). sorry if my understand on the problems differs with yours.

Regards.

 

[ezlynx]

Fortunately, the antenna was already pointed at the mountain behind my home where all the local towers are located so I think it picked up the Verizon tower that was nearby. When I attached the antenna to the device requiring a lower frequency, I didn't use any converters or anything to tamper with the patch antenna and change or improve its ability to receive a lower frequency. Here is the antenna configuration (graph): **broken link removed**

What I wondered is if it unusual or is it to be expected that an antenna designed for a specific frequency will also work quite well with other frequencies? This antenna was designed for a 2500-2700 MHz signal and the device attached uses a 800/1900 MHz frequency. Sorry if my question is not clear enough (I may have misused some terminology).

 

[kspalla]

OK now I am getting more clarity.
The graph is radiation pattern and I am interested in RL of antenna.
May be some thing happening due to loading. Getting 1900MHz signal coverage with 2500-2700MHz patch is a bit ok but 800 is something I am unable to guess.
its getting beyond my imagination.
Take a look at cell phone antenna that uses 5to 10 mil substrate for pattern. if we measure alone film it has some resonance, put in case gets another resonance, put hand or other object it further changes.
My worry is how 800MHz signal is getting good coverage with 2.5to2.7GHz patch. Another point is if it giving service to both 800 and 1900 then its BW is more than 1GHz. Its interesting topic.

 

[ezlynx]

More details on the antenna then:
https://www.l-com.com/wireless-antenna-26-ghz-mmds-14-dbi-flat-patch-antenna-n-female-connector#
2.6 GHz MMDS 14 dBi Flat Patch Antenna
Unsure what RL is but I don't see any specifications that might be RL.

The device using it, Novatel Ovation MC760 requiring a 800/1900 MHz signal mentioned in the first post, specifications found, for example, here:

https://www.wirefly.com/product/verizon_wireless/novatel/u760-usb-modem

Network Compatibility - CDMA 850, 1900

Still curious why the patch antenna seems to improve the signal so effectively when the frequencies are so different.

 

[kspalla]

Good information now.
if I am correct on below spec
Network Compatibility - CDMA 850, 1900
your device is compatible to use either 850 and/or 1900.

I guess you are getting service because of 1900 being serviced by the antenna. it may have poor RL but due to associated 14dB gain, in resulted in good repeater.
The concern I have is the huge gain of the antenna due to it is in other band and may result rejection requirements of this 2.5-2.7GHz in user equipment.

help me more in understanding.
R u using two antennas or only one antenna is facing towards local towers and the antenna cable is connected to usb modem. am I right?
Is the 2.5-2.7GHz dome/cover is removed or bad in shape? i believe if you do not use dome you would like to have lower frequency shift.

Regards.

 

[ezlynx]

The antenna actually isn't all that old (maybe 4 years of use, in good condition, under the eaves). Used it earlier to improve signal for a Navini device (wireless portable broadband, used for 8 years until the device was no longer supported by the manufacturer and the provider quit offering service). A perhaps 12 foot cable connects the antenna to the Novatel device. I figure when connected, the current device uses the new antenna and not the built in one.

I think the device frequency may change within that range (CDMA 850, 1900).

https://en.wikipedia.org/wiki/Code_division_multiple_access
Code division multiple access (CDMA) is a channel access method used by various radio communication technologies.

"CDMA is an example of multiple access, which is where several transmitters can send information simultaneously over a single communication channel. This allows several users to share a band of frequencies (see bandwidth). To permit this to be achieved without undue interference between the users CDMA employs spread-spectrum technology and a special coding scheme (where each transmitter is assigned a code)."

There is a bunch of technical info on that page. I don't know if it will be helpful to you.

 

[kspalla]

I am sure that the device is using 1900 band in your case, though it can use 850.
My concern is that the device is meant for indoor application but now being used as external antenna.
Take care of ESD, lighting and outdoor impacts, if you are careless then it may damage the laptop.
PM me if you need more explanation.

Regards.

 

[ezlynx]

The Novatel U760 USB Modem for Verizon Wireless that is receiving the signal from the antenna is located inside. The antenna is outside. The Novatel device is hooked to a Cradlepoint router that handles the wired and wireless connections to various computers. So it would seem unlikely the antenna would affect the computers.

Thanks for your help. I am going to try to contact the manufacturer of the patch antenna to try to find out why their 2.6 GHz antenna improves the CMDA 800/1900 MHz signal so much.

 

[ezlynx]

I wrote the manufacturer (the original responder just recommended another antenna and didn't reply to my query):

"Is it unusual or is it to be expected that the 2.6 GHz patch antenna you sell also works quite well with my 3G 800/1900 MHz USB device?"

They replied, "Thank you for your interest in our product. That is very unusual because this antenna is only rated for 2.6GHz."

So I am no nearer to understanding why it works on the Novatel device. :-(

 

[kspalla]

Its better to measure the RL of this part (including the cable in my opinion).
I feel more gain of antenna and yet moderate RL giving reasonable amplified reception.
Regards,
Palla

 

[ezlynx]

Can you be more specific about what an RL is and how I would measure it?

I did not see anything in the manufacturer's specs that would seem to be an RL.

I do notice occasional drops, sometimes even really bad (-91dBm) which can change and then stabilize toa much better dBm (currently -77). But overall it is in the acceptable range. I wonder what would acount for the fluctuations in signal strength (sunny, a little wind now, but not much).

 

[kspalla]

RL is Return loss, or the other terminology is VSWR.
Do you have the graph/plot of RL or VSWR over 1800MHz to 2700MHz?

 

[ezlynx]

The VSWR is listed as < 1.5:1 avg. under the specs for this antenna. The only graph is of the gain.