Tråd: 900 MHz Panel Antennas Cyclon 14 and Cyclon 18 - untruths about gain.
The panel antennas Cyclon 14 (nominal gain 14 dBi) and cyclon 18 (nominal gain 18 dBi) were tested by direct connection to a Samsung Gio phone via the test connector using a patch cable. A single GSM cell was tested against, this cell being within sight and 8 dBm stronger than the next neighbor cell.
As a reference antenna, a GSM dipol was used which has a nominal gain of 2.5 dBi and gives a 6 dBi stronger signal than the Samsung Gio internal antenna. The 0 dBi level was determined to be about -70.5 dBm
The best values obtained with each antenna were noted.
The 40x40 cm Cyclon 18 is described by the retailer dibay.eu as a RFID antenna having a 70 degrees wide lobe between half power (-3 dB) points which makes it impossible that the antenna could have a directional gain of 18 dBi. This 40x40 cm large antenna is marked with Yagi.pl in large letters on the plastic dome. Yagi.pl states that the antenna has 18 dBi gain with a 20 degr horisontal beam and a 25 dBi vertical Beam. The best value obtained with this antenna was -59 dBm with low directional capabilities which can be related to the measured gain of 11.5 dBi, not good for such a large antenna with a purported directional gain of 18 dBi. The gain difference is as much as 6.5 dB. Why should one put up a 40x40 cm panel antenna for 900 MHz and only get 11.5 dBi gain? Compare with this dual panel antenna for 900 MHz which consists of two panel antennas of about the same size as the Cyclon 18 and has a nominal gain of 16 dBI:
It should be mentioned that both antennas have linear polarization and that they can be mounted so that the polarization plane is horisontal or vertical. Cell antennas have +-45 degrees polarisation. On reception, this mismatch in polarization causes a 3 db loss in signal strength. On the other hand, the GSM user antenna should be mounted horisontally or vertically in order to facilitate diversity reception at tha base station for the uplink. So strictly speaking, antenna gain could be 3 dB higher than I mentioned although this 3 dBgain can hardly be put to use.
The 20x20 cm Cyclon 14 is described as a GSM antenna with 14 dBi gain. No more characteristics are given. The best signal obtained was -61 dBm which gives a gain of 9.5 dBm, which is as expected for the size.
No tests were made aligning antenna polarisations over the radio link.
On the other hand, these antennas have a low price and can be used on the condition that the buyer is aware of the exaggerated claims of the maker yagi.pl and the reseller dibay.eu. Delivery to your door from dibay.eu is very fast and comes at a very good price which shows good logistics. Both antennas were delivered in three days from Slovenia to Brussels for 11 euro. Dibay.eu could be a good seller if their claims of antenna performance can be trusted. Yagi.pl needs to sort out their messy web site if they wish to sell to other countries.
Any experienced buyer of antennas on the internet know that sellers always lie about the performance of cheap antennas. The question is to what extent in each case. These figures give you an idea for these two antennas. I have reasons to believe that my results are correct within 2 dB.