I purchased my HP 8594E with matching scalar network analyzer (85630A) a number of years ago – a surprise spot bonus.
If I was in the market today, I’d be watching for one of the Anritsu portables, eBay usually has a few of the older MS2711 series for around $1500. These cover up to 3GHz, and are good pices of equipment.
Occasionally one pops up with the tracking generator installed. The Anritsu SiteMaster test sets have the tracking generator and cable measurement functions.
You can also find the (non-portable) service monitorss, which include a spectrum analyzer with other measurement capabilities for around the same price.
Rhode & Schwarz has some portables that pop up as well, like the FSH3.
All these, being microprocessor controlled, have extensive self-test and cal functionality built in. Make sure your unit passes self-test and self-cal!
Yeah, $1500 is a LOT of money for a piece of test equipment – but to me, a spectrum analyzer (with TG) is so worth it.
The frustrating part of this piece of equipment is that, for the price, it’s a surprisingly capable device. The real disappointment is it’s horrible build quality.
$1500 (1.5 Aircraft Monetary Units) isn’t so bad for a professional. It’s hard for a hobbyist to justify that to the CFO. The 1201 comes so very close to being a good solution - hampered by it’s shoddy assembly and materials.
Once this one fails altogether I’ll be doing an autopsy and finding the sloppiest components and potential points of failure and will update this thread with a BOM and instructions for bulletproofing it.
I invested in it and received it.
It looks like a 3 element Collinear, but I’ll have to wait for BangGood to get some more 1201s in and then wait about a month to receive it before I can evaluate it.
The antenna you purchased is from CA USA. Price US $8.99 + US $12.00 Shipping to Canada by USPS, Delivery between Mar. 1 and Mar. 9 ebay.com/itm/232158242330
I found a similar antenna from China. Price US $4.58 + FREE Standard International Shipping, Delivery within 11-22 business days ebay.com/itm/191866128415
Nope, I just measured what appear to be 3 sections, each about 3.5 inches in length - although the section towards the tip might be more like 3".
…good find from China, although when I order from there it takes so long to receive it I’ve forgotten I ordered it - always nice to be surprised thou
You cannot evaluate an antenna using N1201SA.
N1201SA does NOT measure two very important parameters of antennas:
(1) Gain
(2) Radiation Pattern
N1201SA measures R/X/Z/VSWR/S11 and plots VSWR vs Frequency.
This instrument is therefore great help for tuning/trimming of DIY antennas, but NOT for evaluating/comparing antennas.
Better evaluate the new antenna by putting it on trial run for a day or two and compare its performance graph (Message rate plot, Maximum range plot etc) with those of a reference/benchmark antenna.
I’m more interested in the bandwidth of the antenna (resonance) since for a single frequency receiver the best filter is the antenna.
The tighter the bandwidth (containing the signal bandwidth) the greater the gain with no loss like a bandpass filter, only gain.
i.e.:
I’ve got an MFJ Transmitting discone; http://www.mfjenterprises.com/Product.php?productid=MFJ-1868
mounted about 10’ above the roof which commonly tracks out to 150nm and sometimes 250nm (when I use the FA Pro Stick + with its 1090 MHz filter).
When I hook up the NooElec SMArt SDR (no filter) I’m lucky to get 70nm max.
I stuck a NooElec “5dBi” 1090MHz antenna in the window and tried each SDR for 24 hours.
The NooElec got about 50 nm while the FA stick got about 20 nm.
I’m now doing the same “in the window” thing with the “9dBi” antenna.
VSWR will directly translate to performance you see at a given frequency. Gain is a rather misleading and overused figure (G=Efficiency*Directivity~with some caveats). Efficiency is tough to nail down since it is tied to the environment surrounding the feedline/feedpoint - freespace, height above surface, type of surface, surrounding objects - list goes on. Can even add air pressure/density and sometimes how you hold your mouth when measuring. Stick a hand out and that figure changes - so it’s much like nailing jello to the wall if not chamber testing. A narrow and deep VSWR plot at 1090Mhz is what we’d be after - narrow to help eliminate off-band frequencies (filtering helps with that in the end) - this helps mitigate extra noise the demodulator (dump1090 in this case) has to chew through making for a more efficient system. Directivity is the portion of the equation that’s missing in this case - hence no useable values
Also as it concerns this thread, and with any instrument used for sampling - unit temperature (not going to get into actual calibration - that’s already been discussed) will play an active role on things. Usually it’s advisable to pre-heat or get the unit to a good solid working temperature before sampling to help narrow PPM shift/drift which effectively gives more stable/repeatable readings.
Much of what I stated is debateable and I realize that. Point being, these can be fantastic tools for the hobbyist if they are built well enough to stay alive, which seems in some cases they may not be If the readings are reasonably accurate, there is no reason it couldn’t be used to compare and tweak with a good degree of confidence. As a rule of thumb, look for the lower and sharper VSWR plot at your given frequency.
One working example - slap the 26" FA antenna on and will notice that the unit has a relatively low VSWR for a rather large frequency range (flatter VSWR slope) - this shows that this antenna is quite efficient throughout a larger bandwidth. This is the exact reason that some notice performance declines in noisier environments (especially when amp’d) since the demodulator has to chew through spurious noise so packets get spit out due to collision until they slap a filter on to narrow that curve.
This is what I have discovered thrice:
(1) By using 6 dBi FA antenna, first without Filter, and it performed much poorer than 2 dBi Cantenna. I then added a filter, and it started performing better than Cantenna.
(2) By comparing Simulations of a high gain wire collinear and a Cantenna
(3) By testing Cantenna & FA antenna by N1201SA.
Well, this past week Banggood CS asked a lot of questions, I’ve made a video showing my Analyser doing nothing with/without a dummy load, they asked me to show the load resistance, but I’m starting to think I’ll have problems with them. Will give one more day before opening the dispute on PayPal
I’ve been waiting to buy from BangGood for a couple of weeks now. First it was “restock expected 2-19” then “2-24”.
Gave up and surfed the net ending up at alibaba and aliexpress (as opposed to Amazon at $260 - although a new one just popped up at $166):
Asked for best price on aliexpress, got a bid for $162 including slow boat shipping. Attempted to buy but they wanted my SSN, pictures of driver’s license, bank account statements, passport, etc. to “confirm purchase”. After a nano second’s consideration I decided not to provide same and canceled order.
On the same day as above I bid $145 on alibaba, got offered $139+$6 shipping “air express” 5-8 days from “Shenzhen Anysecu Technology Co., Ltd.” .
I’m currently awaiting their response to my reply saying I would buy.
Finally Banggood did the RMA. Now it’ll take at least 30 days to return plus 30 days to ship back.
At least they’ll refund the return fee
Edit 2017-02-23: Banggood CS is exceeding expectations. After sending pictures of the returning package they immediately reimbursed the shipping fee and placed an order to ship another (brand new) product. Still waiting for stock, but a good experience so far, recommended.
Just received my N1201SA this morning, checked the VSWR on 3 "1090"MHz antennas, only one was close to 1090. I’ll post pictures/data when I get organized?.
I paid $160 (145+15 DHL express shipping) ordered on Sunday 2/19 @ 8:15PM pst (noon Monday 2/10 in Shenzhen, China) received 2/24 10am pst - I’m tired of waiting 30 days.
I initially offered $145 to include air express shipping, they countered with $139 +$5 shipping for receiving in 10-15 days, being a shrewd bargainer I offered to pay $15 more.
Anyway, if you’re not in a rush you might get it for $140 including shipping.
…and nope I don’t own stock in it and am uncompensated other than being a 1 day satisfied customer.
Is listed as a 9 dBi 1090 MHz SMA female antenna from an unknown manufacturer.
It is 13 5/8” long from tip to swivel pin.
Are two SMA female antennas from NooElec listed as 1090 & 978 MHz at 5 dBi each.
Each one is 6 ½” long from tip to swivel pin.
Using the analyzer in spot mode then scanning mode with a nylon fishing line tied to the tip of each antenna and the analyzer off the carpet {“free space”} resulted in:
BTW: my N1201SA came with a rattle maybe like aldoir’s.
It also has a seemingly random way of allowing me to turn it on & off.
Sometimes it’s just one press of the Ok to turn on and sometimes off.
Other times the Ok button has to be used along with the CTRL button.
Other times the above buttonologys have to be held for a couple of seconds.
Since the manual doesn’t shed any light on how it’s supposed to be turned on or off - does anyone know how it’s supposed to be turned on and off??
Thanks
ps: sorry for the clumsy post of the 3 antennas, I’ll never be as good a poster as abcd567.
Thanks Nitr0.
Also , I took the base plate off in search of the rattling noise, expecting some loose solder balls to fall out, turns out the rattling is caused by the button caps a designed in feature 8)
by USPS, Delivery between Mar. 1 and Mar. 9
If the readings are reasonably accurate, there is no reason it couldn’t be used to compare and tweak with a good degree of confidence. As a rule of thumb, look for the lower and sharper VSWR plot at your given frequency.
, I took the base plate off in search of the rattling noise, expecting some loose solder balls to fall out, turns out the rattling is caused by the button caps a designed in feature 8)
