Frequency Sweep (From 100 MHz to 2500 MHz) of Wire Collinear Antenna and 1/4 Wavelength Ground Plane Antenna.
The frequency sweep results of a high gain wire collinear antenna show that it not only performs best at its designed frequency, but also performs fairly good at or near sub-multiples and multiple frequencies.
This characteristic of collinears is good for multi-band reception such as single antenna used by Armature Radio Hobbyists for 2 meter band and 6 meter bands. However it has disadvantage for single frequency reception that the RF signals picked from all these multiple & sub-multiple bands necessitates a tuner circuit or a filter at front end (i.e. between antenna and receiver).
The frequency sweep results of a 1/4 wavelength ground plane antenna show that it gives good performance at and near its designed frequency only, and at other far away frequencies its performance is poor. Hence the 1/4 wavelength ground plane antenna picks very little harmonic and sub-harmonic frequency signals.
WIRE COLLINEAR ANTENNA WITH DECOUPLING SLEEVE
Click on the thumbnails to see full size images
Interesting. Are these actual measured plots or simulations? My VNA only goes up to 200MHz or I’d happily build a bunch of aerials and test them.
/edit - btw, I don’t know any of my amateur friends who use aerials designed for 2m or 6m on the other band but there are specific collinears designed to work on both bands along with 70cms. I’ve got one of them on a mast myself. Now running a 40m aerial on 15m is a different matter
These are Simulation plots. I dont have VNA, Signal Generator, Oscilloscope, bridge, etc. Too costly for me.
The only piece of test equipment I have is this one which I purchased for Canadian $9 https://c5.staticflickr.com/1/429/20199959700_05d132c03c_m.jpg
MFJ 1764 6M/2M Super Gain Antennas MFJ-1764
Antenna, 6M/2M Super Gain, Collinear, 2 Elements, 100 W, 50 ohms, 1.92 ft. Boom Length dxengineering.com/parts/mfj-1764
Yeah, I know about those. I read your post as suggesting that radio amateurs were using aerials designed for 2m on 6m and vice versa rather than those specifically sold as being multi band.
I want to purchase a low cost instrument for swr /impedance/frequency sweep of 1090 mhz DIY antennas.
I am considering to buy this one for $184 + free shipping. Has anyone tried it?
I would be interested in this. I have some directional antennas that can be tuned but nothing to tune them with(and no doco on how to tune them).
This would also work well on HAM 2m/70cm/23cm bands as well as 978/1090mhz.
It is in Russian language. I opened it in Google Chrome Browser, which showed an option to translate page in English. I chose it and could read the discussion in English, though translation sometimes was poor.
I don’t think they rated it very highly. Looks like calibration and accuracy are an issue with poor battery life. It’s really quite difficult to work out what they’re actually saying!
I’ve already got a miniVNA Pro which I’ll probably replace with a miniVNA Tiny later this year. That’s good up to 3GHz.
The commentary is again in Russian.
Hovered mouse over video and menubar at bottom of video appeared.
On video menu-bar, at bottom-right, clicked “CC” (subtitles/closed cation), and subtitles in Russian started displaying.
Then clicked the gear icon (settings), again at bottom-right.
On the popup menu clicked “Subtitles/CC Russian(auto generated)” >> Auto Translate >> English, and sub-titles in English started displaying.
I have one of those, handy for trimming aerials and checking they are still alive.
Intend to use it to quickly check my home built collinear aerials before climbing up on the roof - not had much success previously.
Its nice to have some test equipment, my ham stuff does not go up this far, and this for me is affordable.
Was a bit wary sending so much money to China but unit arrived on the first of the date range they suggested.
Don’t see why battery life should be an issue test is more or less instant and has auto switch off. (recharge battery via mini USB)
I have noted two slightly different specs on models on eBay.com.
Some specs have “Scan Points 280”, while some specs dont have this.
I am not sure if this is significant.
Looks older model specs did not have this, but newer model specs have it.
It may simply be an omission in older specifications which has been corrected in new specs.
It may be a new feature added in new models.
Banggood Specs are without “Scan Points: 280”
The Model I posted from eBay has “Scan Points: 280”
I found many on eBay without “Scan Points: 280”
Banggood Specification:
Working currency: 140MHz~2700MHz
Actual currency : 137.5~2700MHz
Stepped frequency: 1kHz
Display: 2.4" TFT trdp
Resolution ratio: 320 x 240(QVGA)
Battery capacity: 2000mAH(7.4Wh)
Power consumption: <1.5W
Charge current: 400mA
Charge port: USB
Auto power off can be set 5-60minutes.
Measured parameters: Resistence, Reactance, Standing wave, S11
Resolution ratio: 4 number
Frequency accuracy: about 5ppm
Connector: SMA-K
Working temperature: 0~40℃
Atmospheric pressure: 860hPa~1060hPa
This instrument has four interfaces: single point measurement, scanning, system information, correction and calibration
The default boot into single-point measurement interface.
Can you please check specs given on eBay site for the one you ordered. Does it has “Scan Points: 280”?
Anyway, due to big price difference, I am going to order Banggood one, even though its specs dont mention “Scan Points: 280”.
The pics on the banggood site show different model numbers. The first pick shows N1201, missing the SA. Other pics have the SA in the model number,
The description does state SA in the text.
I’ve also been eyeballing the MiniVNA Tiny. Have seen a couple really good youtube videos on the Tiny and it appears to be a decent happy medium as opposed to $1500~$40k+ for measurements. Obviously none of the devices discussed here would be for professional use, but for the hobbyist, $425 or thereabout is much more appealing. The lack of proper documentation on the other device mentioned raises a red flag to me. I question the support going forward whereas Miniradiosolutions has been around for quite some time and appears to retain support and the software has many useable functions. Not as simple to be dragging up to a roof-top however, but there are always compromises. Then again, we’re still talking ~$150 vs ~$425 as well…
