How to make mimo 2x2 yagi antenna with wide frequency range from 1700-3600MHz - Page 1
Forum section: electronics / rf-microwave

author: rfelement
author_rank: Newbie
timestamp: December 17, 2022, 03:52:22 am
content: Hi, all,We are one custom5g antenna manufacturerin China. In order to meet the demand of 4G 5G signal long distance transmission, recently we develop one kind of mimo 2x2 yagi antenna with the wide frequency range from 1700MHz to 3600MHz, meeting the 4G and 5G N78 application.Base the previous，900MHz mimo 2x2 yagi antenna, our RF engineers changed the aluminum circle size, making it more larger. In additional, add one more the same aluminum circle to ensure the high frequency band performance.However, The VSWR of this kind 4G 5G mimo yagi antenna is not that good at the frequency band from 1700MHz to 3600MHz, especially on the 5G n78(3500MHz), the VSWR is quite high, even more than 5.0.May I KNOW that is it possible that the dual polarity mimo yagi antenna can be so wide band (from 1700MHz to 3600MHz)? Since our engineers had tried various methods to make this mimo yagi antenna.Thanks a lot!

author: radiolistener
author_rank: Super Contributor
timestamp: December 17, 2022, 07:19:11 pm
content: bandwidth, Q-factor and VSWR of antenna are things which are always coupled together:VSWR = (Q^2 * BW ^2 + sqrt ( Q^2 * BW^2 * (Q^2 * BW^2 + 4)) + 2) / 2whereBW is normalized bandwidth (relative to the resonant frequency: BW = bandwidth / frequency)VSWR is VSWR within specified bandwidthQ is the antenna Q-factor at resonant frequencyIf you improve one thing you will lose other things. This is why wideband antenna always have bad performance. It means that more wideband antenna has more worse performance.So, if you're trying to make very wideband antenna, it means that you're trying to make very bad performance antenna.What is more important for you - wide bandwidth or high performance of antenna?

author: paul@yahrprobert.com
author_rank: Regular Contributor
timestamp: December 17, 2022, 07:27:20 pm
content: Such a large bandwidth is not possible with conventional yagi designs. Yagis rely on the driven element being a resonant dipole and the parasitic elements being tuned about 10 percent off resonance.Perhaps you should look into a log-periodic design. Such an antenna looks like a Yagi but all the elements are driven and the lengths vary over a wide range. These antennas can operate over a 10:1 frequency range if so designed.

author: kahe40
author_rank: Contributor
timestamp: December 19, 2022, 12:04:12 pm
content: like Paul said, look at log-periodic antennas, like this,but must be new calculated for your 1.7G to 3.8Ghttp://www.wa5vjb.com/products1.htmlCalculator online:https://www.changpuak.ch/electronics/lpda.phpPrototyping with PCB- material:http://www.vk2zay.net/article/43Vivaldi antenna maybe?https://www.eevblog.com/forum/rf-microwave/ultrawideband-antenna-design-write-up-pedantry-required/https://www.antenna-theory.com/antennas/aperture/vivaldi.php

author: kahe40
author_rank: Contributor
timestamp: December 19, 2022, 12:27:27 pm
content: have just seen this message about Planar Disk, it is not a Yagi,but maybe you try it, because construction is very easyhttps://www.eevblog.com/forum/rf-microwave/antennas-for-experimentation/msg4526612/#msg4526612

author: David Hess
author_rank: Super Contributor
timestamp: December 19, 2022, 05:09:54 pm
content: It is possible to interleave two sets of yagi elements to cover two different bands, but that is even more difficult in a dual polarity design.I agree with the previous statements that a log-periodic antenna design is more suitable.