Uniden R4 Review: Best Single Antenna Radar Detector

Uniden R4 Review

A supercharged Uniden R3 with some impressive new capabilities

The Uniden R4 is one of the best radar detectors currently available and is now an even better value given a recent price deduction of $70, to $379.

See why we regard this single-antenna radar detector as being the best at any price with this Uniden R4 Review.


Uniden R4 Review
Updated: 3/25/2024, by Veil Guy


Back in September of 2021, the owner of RadarBusters and I recently went on a 16,000 mile road-trip throughout large parts of the United States to the Eastern provinces of Canada.  Victoria and I had been recently vaccinated so when the prime minister of Canada re-opened its borders to vaccinated citizens with proof of a negative COVID test, we jumped at the opportunity to visit.  I’ve been to Canada a good number of times, but for Victoria, this was her first trip there. The provinces we visited included Ontario, Quebec, New Brunswick, Prince Edward Island, Nova Scotia, and ultimately Newfoundland.

The trip lasted for nearly 45 days and during the course of driving, we tested a bunch of radar detectors during the extended trip the way I prefer to do so, in the real-world, including the Uniden R7, the Escort Redline 360c, and the soon-to-be-released Uniden R4.

We have a incredible story to share in the future about one radar encounter in Quebec, so stay tuned for that one!

Real-world Radar Detection Performance

Having had extensive driving time with both the Uniden R7 and the Uniden R3, it’s been my experience that the Uniden R7 tended to out alert the Uniden R3 to police radar to an estimated tune of about 2dB in increased sensitivity.  We found the new Uniden R4 not only erased that difference but added another 2dB on top of the Uniden R7’s sensitivity.  This is due to the fact the new Uniden R4 incorporates dual LNAs (low-noise amplifiers), one for X & K bands and the other for KA band.

On paper, LNAs have the potential to increase sensitivity by 6dB over their non-LNA counterparts, but in practice we found the increase with the Uniden R4 to be approximately 4dB overall.  When one considers that each dB increase represents an approximate 13% increase in potential detection range, the Uniden R4 provides a potential increase of about a 28% in detection range over the Uniden R7.

In the course of real-world driving, however, the alerting differences between the Unidens are typically smaller.  In any event, the Uniden R4 builds upon the very very impressive performance of the Uniden R3 and provides its driver with as much sensitivity one could ever really need.  Detection performance is consistently strong on all three Ka-bands found in the US.

The Uniden R4’s K-band performance appeared more on par with the Uniden R7 and by my estimates is a 1dB or 2dbs less sensitive than the Uniden R8.

Also noteworthy, the Uniden R4 performed fabulously with X-band (which can still be found in a couple of states) and even exceeded the performances of R8 and the Escort Redline 360c where the Escort detector had previously been the leader in this aspect.  My guess it’s about 2dBs more sensitive than the dual-antenna R8 which I attributed to the tuning of the R8 perhaps to favor K and Ka band with its wave-guide (convex lens on the rear).

The Uniden R4 adds a new auto radar sensitivity mode which automatically reduces sensitivity at slower speeds.  This feature may appeal to those who frequently drive in both city and highway traffic conditions.

Police Laser Detection

The Uniden R4 has decent laser detection capabilities and now has the ability to identify (and display) the type of laser you encounter.  We tested it against the LTI Truspeed SXB, Kustom Pro Laser 4, Stalker XLR/RLR, and the DragonEye Compact and the Uniden R4 was able to identify them.

Unlike police radar, police laser is harder to detect at close range.  Since we hadn’t encountered enough police laser on the road, we tested ourselves with the above guns against a black Mercedes sedan with the Uniden R4 mounted at the center of the windshield.

At distances of about 600 feet and beyond, the Uniden R4 was able to alert in most cases.  While we don’t ever test laser using a tripod (since all real-world police laser usage is hand-held), we did test in both stabilized and non-stabilized hand-holding.  Detections improved to even shorter ranges with non-stabilized hand-holding–the way most police target today.  Laser detection tends to improve further when one drives with lighter colored vehicles having sloped hoods because reflections of laser off of the hood tend to be more easily detected. So with lighter vehicles, laser detection performance should improve further.

While many enthusiast sites pushing laser jammers, boast about the importance of being able to perform as super close ranges (to help promote expensive equipment), the reality is that laser is most lethal at farther distances when you can’t even see the police officer targeting you.  I’ve been targeted at distances of 2400 feet and more in another of states including Wisconsin, Maryland, Delaware, and Kentucky.

Once, I received a hefty speeding ticket while I was driving a rental car south of Madison, Wisconsin on Interstate 90.  The police officer targeted me from nearly 2700 feet away, long before I even saw him sitting low in the median. So in this context, the Uniden R4 provides sufficient detection performance and I am especially pleased that it can alert to the variable-pulse/anti-jamming pulse-rates of the latest police lidars like the Stalker RLR and DragonEye Compact.

When paired with the new Veil G6 Stealth Coating, the Uniden R4 should provide adequate time to slow down in the event you were speeding if you are targeted with laser in many instances.

Detection of Advanced Radars

When configured to detect it, the Uniden R4 consistently alerts to MultaRadar MRCD/MRCT systems that are increasing in popularity, particularly in the state of Texas.  In fact, its been my experience that Uniden radar detectors are the best and most consistent at detecting these systems.

The Uniden R4 is also designed to detect Sensys Gatso radars, one to the very few radar detectors to do so.

Some years ago, we tested a bunch of radar detectors outside of Los Angeles and none of them were able to alert to the Gatso RT4 that was being deployed at a number of intersections.  Those systems have since been deployed and when we drove through a section of Iowa recently, we didn’t have the benefit of being able to test the Uniden R4 so until we actually encounter an RT4 in actual use, we will have to wait to see how it performs.

To test the falsing potential, of this Uniden detector, we did drive with the feature enabled and we did find it falsed occasionally to K-band collision avoidance systems of certain vehicles more so than it did with MRCD/MRCT enabled but it was tolerable.  I trust as Uniden continues refining this detector which future firmware updates, its behavior will improve.

Filtering of K-band blind spot monitoring (BSM) and collision avoidance radar

When K-band filtering is enabled as well as K-blk 1 & K-blk 2 set to WEAK–which reduces falses from certain vehicles like Hondas and Acuras–we found the Uniden R4 to behave very well.  While the Escort Redline 360c is a little bit quieter (so long as MCRD is not enabled on it), the alerting nature of the Uniden R4 when it falses is much improved over the Escort piece and frankly, I trust the police radar K-band detection performance of the Uniden.

When the Uniden R4 does alert to a K-band BSM system, it alerts very gradually as one approaches such a vehicle.  This is in contrast to Escort radar detectors which often remain silent but them wail full-strength as if you are encountering instant-on police radar at very close range.  The result if the Uniden R4 is much easier to live with day to day.

Auto Lock-out of Stationery Sources of Radar

Escort’s patent on auto lockouts, based upon GPS location, has expired which has allowed other manufacturers of GPS radar detectors, including Uniden, to incorporate this feature.

The behavior of the Uniden R4 is similar in that the detector can be configured to automatically mute stationery sources of radar when one drives through an area over time.  If the stationery source ceases to operate or is moved, the Uniden detector will “unlearn” the location and free up the storage space occupied by it.  As this is a new feature for Uniden, the effectiveness of auto-lockouts will improve over time.

I personally never have preferred to avail myself of such a feature, but there are those that do and as such it will be a welcomed addition to the Uniden R4.

The Uniden R4 also has additional memory for storing a greater amount of locations than its predecessor, the Uniden R3.

Of course manual lockouts are still possible with the simple pressing of the Uniden’s power-cord mute button twice and the Uniden R4 has the ability to lockout both X & K band sources as well as Ka-band and advanced MRCD radars.

While there are plenty of 34.7 Ka-band speed signs on the road, given the popularity of the band with genuine police radar, I would urge caution in locking out Ka unless you know that Ka isn’t deployed in your driving area (such as the entire state of PA).  Otherwise, I like to be reminded that my detectors continue to operate in tip top shape in detecting Ka.


SPECTRE RDDs (radar detector detectors) can be found in Canada, Virginia, and at some truck weigh stations.

We prefer testing SPECTRE immunity with the older SPECTRE III, as the newer SPECTRES are more heavily filtered and are not as sensitive as the III.

We tested the Uniden R4 in eight configurations to determine if and how it could be detected by police in the real-world and in a variety of encounters.  Surprisingly, we found the Uniden R4 slightly easier to detect than the dual-antenna Uniden R8 but detections sometimes did not happen at all, as well.  It was hit or miss.

When passing the “patrol” car in the opposite direction of travel, we would very occasionally detect the R4 as far as 185 feet, but generally detections, if they occurred, happened much closer, once briefly at 43 feet and then more consistently at 27 feet.  It would be enough to warrant the attention of the officer is you were passing on a two lane highway, however.

When overtaking in the same direction of travel, we would occasionally get a brief alert to the R4 just as we were beginning to pass the vehicle on either side.

When approached by the car with the R4 directly from behind in the same lane, the patrol car was unable to detect until the R4 was within about 30 feet or less, or a couple of car lengths, where we were able to get consistent detection.  In the real-world, however, you wouldn’t follow a patrol car this closely, so provided there was a car length or more between the two of you, the officer would not likely get a detection of the R4.

We also simulated a situation where the patrol car was sitting in the median perpendicular to the road.

In this setup. the SPECTRE was unable to alert to the presence of the R4 before the vehicle passed, but occasionally was able to get a brief detection as the vehicle passed by.  Now granted, we were very close to the road–closer than what would be the case normally–so in-the real-world we don’t believe the R4 would be detected on the highway in this arrangement.

There we also times that the SPECTRE did not alert to the presence of the R4 at all, but there were enough detections that could lead to scrutiny from an officer when in close proximity to a patrol vehicle equipped with SPECTRE.

So while the R4 is not completely immune to SPECTRE RDDs, it’s still good.

In my opinion, though, having SPECTRE immunity, while nice, is not foolproof and I have an article that I will be publishing soon explaining why.


Like the Uniden R3, the Uniden R4 has a wonderfully bright and readable multi-color OLED display for its size that now includes two display modes and an autodimming feature based upon actual ambient light which allows for more discreet driving in the evening.  Compared to other company’s multi-color displays, the R4 is easily the most readable even during the daytime.  The display’s eight colors can easily be changed in the detector’s menu programming.  My personal preference is for either amber or white.

The Uniden R4 now has the ability to display its alerts in two different arrangements, although my personal preference is to maintain its appearance to the Uniden R3 as its easier to read (for my aging eyes) from a distance.

Beyond these two different arrangements, the detector can be configured to display your real-time speed, your speed and direction of travel, direction of travel only, your vehicle’s electrical voltage output, or altitude.  I occasionally use the voltage mode to check the health of my vehicles’ battery and alternator output.

I generally select the speed and compass display mode. When driving in Canada (where posted speeds and distances are in the metric system) I select KM/H over MPH speed display.

Audio Behavior

Alert Tones

Like other Unidens, the R4 has a plethora of different alert tones to select from, each of which can be assigned to the specific band or type of radar and laser.

My recommendations for tone selection are:

  • Laser – Tone #10
  • Gatso – Tone #8
  • MRCD/MRCT – Tone #8
  • Ka Band – Tone #9
  • K Band – Tone #2
  • X Band – Tone #3

Similar to Valentine, the R4 can indicate detection of additional radar during an existing alert, but offers five user-selectable tones to choose  from.

My recommendation is for assigning tone #1 for both bands.

Sound Levels

The R4 can be configured to alert quietly or quite loudly and depending upon the vehicle I am driving, I will choose the volume accordingly.  When I use the detector in my Jeep Wrangler Rubicon, I set the volume on a higher setting because of the in-cabin noise.

When driving with a Mercedes or BMW, I tend to set it lower because of the quieter cabins.  In either case, if I am cranking the music, I like to know that I can set the volume loud enough to still be able to hear it alert when I need it to.  I am very pleased with the range of volume choices especially considering the small size of the detector.

Design & Packaging

The appearance and design configuration of the R4 is a nice improvement over the Uniden R3 and appears more upscale.  The power cord and audio jack interfaces have been moved to the right side of the detector, which is my preference for keeping cords away from my steering wheel and right leg.

The USB connection port has been updated to the more current and smaller MicroUSB interface.

On the left side of the R4 there is a small RJ type interface that can be used to interface to Uniden’s yet to be released laser jamming system.

Similar to Valentine, the R4’s cigarette lighter supports the daisy chaining of a remote control module that incorporates all of the buttons located on the detector itself.  The control module doesn’t have a display built-in but will act similarly to the control modules found on custom-installed detectors and jammers from Escort.  The real value of having this sort of remote module will increase when the laser jamming system is ultimately incorporated into the detector.

The windshield bracket interface has been updated to be compatible with any future Unidens that may be released, a very welcomed addition, which will reduce the amount of different accessories needed if you own more than one Uniden radar detector.

The R4 also has quietly added built-in bluetooth capability to interface with future smart phone applications, the specifics of yet has not yet been announced.  The configuration features will eventually appear in a future firmware update.

Speaking of firmware updates, the R4 is ushering in a much improved software program, which similar to Escort, will connect to the internet and download and install both firmware and photo database updates eliminating the need to manually search out the updates online.

For the sake of review brevity, many features of the R4 are similar to the Uniden R3 and can be found in our in-depth Uniden R3 review.

Uniden R4 Review Conclusion: Why its the Best Single-Antenna Radar Detector

The Uniden R4 is a significant upgrade to the Uniden R3, bringing significant increases in sensitivity to radar over the already incredibly sensitive Uniden R3 and brings along a host of new features and future expansion capabilities.

The revised retail price of the Uniden R4 is $379, $20 less than the Uniden R3 when it was first released.

At least for now, the Uniden R4 is the best single-antenna detector currently available and given its performance and feature set is well worth the asking price.

It’s simply amazing that within a short amount of time, Uniden has gone from an obscure position in this industry to a dominate player.  Quite simply, the Uniden R4 comes with my highest recommendation.

The Uniden R4 is now joined by a dual antenna version, called the Uniden R8, which is the successor to the Uniden R7

The best custom installed radar detector and laser jammer, the Uniden R9 , has both front and rear antennas which are essentially weatherized Uniden R4s.

We recommend RadarBusters for those interested in buying a Uniden R4.  In most cases, you’ll pay no sales tax and RadarBusters offers free two-day shipping.