P4P antenna dBi # (eg. 6dBi, 10dBi)

Boz

Joined
Mar 31, 2017
Messages
30
Reaction score
7
Age
47
Hi again guys,

I REALLY want top distance/range from my P4P without signal loss - but I only wanna buy once, so I've gotta get it right!

I completely get GHz now, I just don't really know what dBi numbers (high or low) mean to distance/range in generally wide open spaces. (..I'm far from big city living).

Also I see a lot of reflective cups that sit behind the antenna on the P3 & other models. ..do they do any good & if 'YES', is there a P4P version?

Thanks heaps!
 
Joined
Mar 4, 2017
Messages
21
Reaction score
3
Decibel-isotropic (dBi) refers to "decibels relative to isotropic radiator". Decibel was a term coined by Bell Telephone Laboratories to measure transmission loss in one mile of cable at a frequency of 795.8Hz. OK? Now, ram-dump all that and think of a perfect omni-directional antenna that transmits power in all directions. The signals would appear as a sphere and the power measured on any point of the sphere would be the same as any other point. The antenna doesn't exist but it's power would be 0dBi. Now think of the antenna transmitting in a single plane around the antenna (like Saturn's rings). The power measured on the edge of the ring would be more than measured at, say, directly overhead the antenna. That ratio is expressed in dBi and is the "gain" of the antenna. When comparing the dBi of two antennas, it's imperative to know the angle of the beam. For example, two antennas might be 7dBi but one radiates horizontally in a ring, as previously described. The other has a beam width of 60 degrees (30 above and 30 below the previous antenna). Which one is more useful to the remote controller transmitter/receiver and the UAV? With the first, you would have to point the radiation pattern of the antenna directly at the UAV. With the second, you only need to keep the UAV within the beam width. Now, let's confuse the scenario with two dipole antennas (what is furnished with your DJI controller). Without going into wavelength and frequency, imagine that each antenna is producing the same doughnut pattern as we previous examined. One antenna is the "north pole" and one is the "south pole". A new doughnut ring is produced, between them, that extends beyond each the two antenna's propagation. Imagine the new doughnut being squeezed between each of the doughnuts produced by each antenna. The new doughnut is "squished", meaning its signal is farther but its beam width is narrower. That's basically why dipole antennas are superior to one omni-directional antenna. Now, let's take off the two omni antennas and install a directional antenna that is flat. Instead of the signal propagating in a 360 ring, it is more directional, in the horizontal and vertical planes. Though we don't see the "innards" of the antenna, it is also a dipole arrangement (both outs of the controller feed into the antenna). The dBi of this antenna will be greater than an omni antenna but it's pattern is much more directional. Think of the P4 flying in a 360 pattern: it would be necessary to keep turning the controller toward the P4 to ensure the signal to and from the P4 was within the beam width of the antenna. Similarly, if we held the directional antenna in a horizontal position, the farther away the P4 is in horizontal distance, the more likely it will be within the beam width. As it gets closer, the more likely the P4 will be above or below the beam width. Think of a plane on approach to a runway with an instrument landing system. The pilot gets feedback whether the plane is above or below the glide slope and right or left of the glide path. It means the plane is either within the strongest signal or straying toward a weaker signal. If the signal is lost, it is no longer within the beam width of the ILS system. Just as with the omni antenna, it is essential to know the beam width of the directional antenna, for dBi to be meaningful. If we connect amplifiers to each pole of the amplifier, the characteristics of gain and loss of the antenna are not changed. The antennas must be bi-directional to increase the amplitude of the transmission/reception signal. The DJI controller/antenna is a designed system. When you introduce an amplifier for transmission/reception, you can overload the built-in receiving amplifier. Using an external amplifier can also result in unwanted "reflections", in an urban area, with buildings and structures. An amplifier can't improve the signal quality of a poorly designed antenna system. Start with a well-designed antenna for the drone then add an amplifier.

Now that we know about antenna gain, what about antenna "loss". That figure is a ratio of the transmitted signal over the loss in the reflected signal. The greater the ratio, the more efficient the antenna is. Historically, loss has always been represented as a negative number. Thus, an antenna with -7dBi is less efficient than a -14dBi antenna. This signal is measured by connecting a microwave network analyzer that measures signal loss. An antenna manufacturer can claim any dBi gain or loss but the network analyzer is the "lie detector". Did you get a printout of the DJI antenna's gain and loss? There is at least one aftermarket antenna manufacturer who measures the gain and loss of the antenna and coaxial cables you receive and gives you a printout of the results. Of course, these figures are in a laboratory but a good starting point. Many factors can effect the antenna's connection to and from the controller and P4, such as trees, buildings, landscape, weather, direction and many others. Of the antenna manufacturers that produce aftermarket antennas pick WiFi antennas they manufacture and adapt them to use on the DJI controller. The same company that gives you the network analyzer report designs it's DJI antennas specifically for the controller and the UAV.

The newer DJI quadcopters use both 2.4GHz and 5.8GHz signals for control and video feedback. For an antenna to work with these newer models, such as the P4P, it must be capable of transmitting and receiving on both frequencies. Guess what? The same company that gives you the network analyzer printout designed one of the first dual band antennas for the P4P and the Inspire 2. They now have a model for the Mavic Pro.

Which antenna is best for you? Get both! when you have line-of-sight signal with the drone, the directional will be better for maximum signal propagation/reception. When you're in an urban area, disconnect the directional antenna and connect the two omni antennas. With the P4P, you are going to need a dual band antenna. If you decide to use amplifiers, they must be dual band, also. Amplifiers introduce a point of failure and are not needed when there is a strong signal between the controller and P4 (if you can control the P4 and have video/ battery feedback, an amplifier is not needed).

I'm not an antenna or amplifier expert and there are so many variables that effect signal strength, it makes it very difficult to compare antennas. I do trust antennas that are made by antenna experts that design antennas specifically for the DJI system and back up their design with lab results and actual tests.
 
Last edited:

Boz

Joined
Mar 31, 2017
Messages
30
Reaction score
7
Age
47
Thanks for all that info bluetec.

I ended up buying these off eBay:



Please let me know if they're gonna help me
 

Attachments

  • IMG_0385.PNG
    IMG_0385.PNG
    1.7 MB · Views: 436
  • IMG_0386.PNG
    IMG_0386.PNG
    542.8 KB · Views: 481
Joined
Mar 4, 2017
Messages
21
Reaction score
3
Boz, those antennas are not dual-band 2.4/5.8GHz. They are only designed to cover the 2.4GHz frequencies. They made a claim, in their add, that they would work on the P4P and P4P+. If you look on their website, you'll see they are for the P3Standard and they've thrown in an extra dipole so you'll have two for the P4P. Their two directional antennas are a PIA because they go different directions and won't stay in one spot. I would file a complaint against the seller that the antennas are defective for what they claim in their add. Even if you operate your controller in the 2.4GHz range, your video feed is still in the 5.8GHz range. The seller will have to pay to have them returned and issue you a refund. Ask them "where's the proof" that each of those little directional antennas have a gain of 10dBi. Their antennas for the DJI seem to be widely sold in North America, because there is little competition, but not very well amongst DJI pilots in the Asian market. Search on eBay for these; stocked in the U.S. by an authorized dealer:

s-l500.jpg
4cd3f0_e2d352acc31b4e1e9588473b9fbbcdc8~mv2.jpg
 
Last edited:
  • Like
Reactions: Boz

Boz

Joined
Mar 31, 2017
Messages
30
Reaction score
7
Age
47
Thanks bluetec, & I appreciate your patience.

So do I need to have two diff GHz antenna plugged in?
Eg. one antenna @ 2.4GHz & one @ 5.8GHz.

Wish I could learn this shít faster..
 
Joined
Sep 9, 2016
Messages
8
Reaction score
0
Age
66
I use the parabolic reflectors with my P4 and have had fantastic results as long as you keep the antennas pointed towards the aircraft.
 
Joined
Mar 4, 2017
Messages
21
Reaction score
3
Boz, those antennas are not dual-band 2.4/5.8GHz. They are only designed to cover the 2.4GHz frequencies. They made a claim, in their add, that they would work on the P4P and P4P+. If you look on their website, you'll see they are for the P3Standard and they've thrown in an extra dipole so you'll have two for the P4P. Their two directional antennas are a PIA because they go different directions and won't stay in one spot. I would file a complaint against the seller that the antennas are defective for what they claim in their add. Even if you operate your controller in the 2.4GHz range, your video feed is still in the 5.8GHz range. The seller will have to pay to have them returned and issue you a refund. Their antennas for the DJI seem to be widely sold in North America but not very well in the Asian market. Search on eBay for these; stocked in the U.S. by an authorized dealer:

s-l500.jpg
4cd3f0_e2d352acc31b4e1e9588473b9fbbcdc8~mv2.jpg
 
Joined
Mar 4, 2017
Messages
21
Reaction score
3
Boz, both antennas must be capable of 2.4/5.8GHz. You install two omni-idirectional 2.4/5.8GHz antennas on the the P4P because they act as dipole antennas. If you buy the directional (flat panel) it is 2.4/5.8GHz and it connects to both antenna outputs because it is dipole also. Before you buy any antenna, make sure you are comfortable taking your controller apart, to install the new connectors/cables. The HwaYaoTek has step-by-step instructions and all the tools are included. Unlike any other system, HwaYaoTek tests every antenna before shipping. The network analyzer report for each antenna is printed and included with the kit. If they tell you an antenna is 7dBi, they prove it to you.
 
Joined
Feb 12, 2015
Messages
11
Reaction score
0
decided to try the HwaYaoTek. Omni gave me 2 miles before I started dropping bars, the panel didn't drop bars at 2 miles and both were getting a lot better penetration (western Washington, lots of trees!) than stock. Pleasantly surprised by these (hadn't even heard of the brand until 3 days ago)
 
Joined
Jan 20, 2017
Messages
422
Reaction score
115
Age
59
decided to try the HwaYaoTek. Omni gave me 2 miles before I started dropping bars, the panel didn't drop bars at 2 miles and both were getting a lot better penetration (western Washington, lots of trees!) than stock. Pleasantly surprised by these (hadn't even heard of the brand until 3 days ago)
Where did you get the HwaYaoTeks from??
 
Joined
Jan 20, 2017
Messages
422
Reaction score
115
Age
59
Thanks! And I assume that you are just running it using the 2.4ghz side of the P4P? I didn't see a connection for the third 5.8ghz wire. I could be wrong but I was thinking that the P4P has the 5.8ghz antenna mounted inside of the transmitter.
 
Last edited:
Joined
Mar 4, 2017
Messages
21
Reaction score
3
Thanks! And I assume that you are just running it using the 2.4ghz side of the P4P? I didn't see a connection for the third 5.8ghz wire. I could be wrong but I was thinking that the P4P has the 5.8ghz antenna mounted inside of the transmitter.

The HwaYaoTek antennas, both omni and directional, are dual frequency, meaning 2.4/5.8GHz. There are two antenna connections on the P4P controller because the antennas are a dipole arrangement and require two antennas of the same frequency. The flat panel antenna has two antennas inside the case. The P4P only uses two antenna wires.
 

Ozz

Joined
Sep 7, 2016
Messages
82
Reaction score
17
Age
52
These look decent -
is there one suitable for the Phantom 4 (not pro) - preferably in Europe?

I can only find them with a min order quantity of 10 units on aliexpress.

thanks.A.
 
Joined
Feb 16, 2021
Messages
1
Reaction score
0
Age
38
online searching for antenna and found this. to the fella raving about needing dual band antenna you don't.
on the phantom 4 pro it selects the best frequency at the time. it never uses both at once. you can manually select 2.4
 

New Threads

Members online

No members online now.

Forum statistics

Threads
141,474
Messages
1,455,957
Members
103,259
Latest member
matheus moura da silva